Rania Béji
email: r.beji@montpellier-bs.com.

Ouidad Yousfi
email: ouidad.yousfi@umontpellier.fr.

Abdelwahed Omri

Corporate Social Responsibility and Corporate Governance: A cognitive approach

Keywords: Corporate Social Responsibility, Corporate Governance, Diversity, CSR committees, Corporate Social Responsibility Performance, Financial Performance

This chapter aims to critically review the existing literature on the relationship between corporate social responsibility (CSR) and corporate governance features. Drawn on management and corporate governance theories, we develop a theoretical model that makes explicit the links between board diversity, CSR committees' attributes, CSR and financial performance. Particularly, we show that focusing on the cognitive and demographic characteristics of board members could provide more insights on the link between corporate governance and CSR. We also highlight how the functioning and the composition of CSR committees, could be valuable to better understand the relationship between corporate governance and CSR.

Introduction

Since the start of the new millennium, researchers have been looking for an alternative way to achieve sustainable development and better utilization of the firms' natural resources [START_REF] Carvalho | The disclosure of information on sustainable development on the corporate website of the certified portuguese organizations[END_REF]. Companies have become more aware of the negative impacts of many business operations on the environment and society, specifically longterm effects. To overcome the short-term thinking, many firms have become more involved in socially and environmentally responsible strategies to improve their social, environmental and financial performances. This leads to the emergence of a more inclusive philosophy in businesses going beyond stockholders: CSR.

According to [START_REF] Ashrafi | How corporate social responsibility can be integrated into corporate sustainability: a theoretical review of their relationships[END_REF], CSR is a long-term approach that aims to bring a multi-dimensional added value to social, environmental, and economic spheres. Nowadays, responsible companies not only fully meet the applicable legal obligations, but also go beyond by extending their efforts to promote more socially responsible projects. For instance, companies, such as Starbucks and Orange, have become more concerned about the protection of human rights, employees' conditions, environmental issues, and communities' expectations.

According to [START_REF] Bocquet | CSR, innovation, and firm performance in sluggish growth contexts: A firm-level empirical analysis[END_REF], [START_REF] Zerbini | CSR initiatives as market signals: A review and research agenda[END_REF], and [START_REF] Goyder | Redefining CSR: From the Rhetoric of Accountability to the Reality of Earning Trust[END_REF], there are two CSR strategies: (1) strategic CSR which ties in with the highest level of commitment and implies a more comprehensive implementation of CSR within a firm and (2) responsive CSR where CSR involvement is mainly determined by external expectations and reporting standards and corresponds to the lowest level of commitment.

CSR has been considered as one of the most important challenges of corporate governance. Companies and their boards of directors have to integrate socially responsible investment into their overall approach [START_REF] Jamali | Corporate governance and corporate social responsibility: Synergies and interrelationships[END_REF]. Due to the increasing attention paid to CSR, scholars have examined the various antecedents of CSR.

On the one hand, there is an extensive literature on how CSR could influence the firm's performance and risks. Some CSR related studies have shown evidence that CSR activities lead to financial and non-financial benefits [START_REF] Famiyeh | Corporate social responsibility and firm's performance: empirical evidence[END_REF][START_REF] Hategan | Testing the correlations between corporate giving, performance and company value[END_REF][START_REF] Reverte | The influence of corporate social responsibility practices on organizational performance: evidence from eco-responsible Spanish firms[END_REF]. For instance, various empirical studies have concluded that socially responsible firms tend to have better social ratings and consequently are able to reduce their financial risk [Bouslah, et al., 2016;Harjoto and Jo, 2015;and Benlemlih et al., 2014]. Other studies have provided evidence on the existence of a negative correlation between CSR and financial performance [START_REF] Galant | Corporate social responsibility and financial performance relationship: A review of measurement approaches[END_REF][START_REF] Kim | Corporate social responsibility and stock price crash risk[END_REF][START_REF] Lee | Employee perception of CSR activities: Its antecedents and consequences[END_REF]and Baird et al., 2012]. We notice, however, that several emerging evidence shows insignificant relationships between the firm involvement in CSR activities and financial performance [Javed et al., 2016;[START_REF] Reverte | The influence of corporate social responsibility practices on organizational performance: evidence from eco-responsible Spanish firms[END_REF]and Barnett and Salomon, 2012].

On the other hand, there is an emerging brand of the literature on the role of boards of directors in managing the firm's corporate image and shaping strategic orientations [Schepker et al., 2018;Schulze et al., 2001;Walsh and Seward, 1990]. In fact, CSR seems to be influenced by the choices, motivations, and values of those involved in the decisionmaking process. Accordingly, taking into account demographic attributes of directors such as gender, age, nationality, educational background, and multiple directorships, could be very helpful to better understand the board's dynamics and how they could influence the firm performances from different perspectives [Won-Yong et al., 2019;[START_REF] Tasheva | Integrating diversity at different levels: Multi-level human capital, social capital, and demographic diversity and their implications for team effectiveness[END_REF]Haniffa and Cooke, 2005;and Gibbins et al., 1990]. For instance, more diverse attributes on the board could lead to better organizational outcomes [Won-Yong et al., 2019]. Besides, the resource dependence [START_REF] Pfeffer | The External Control of Organisations: A Resource Dependence Perspective[END_REF], resource-based view [START_REF] Wernerfelt | A Resource-Based View of the Firm[END_REF][START_REF] Barney | The attributes of top management teams and sustained competitive advantage[END_REF], social categorization [START_REF] Tajfel | Human groups and social categories[END_REF], upper echelons [START_REF] Hambrick | Upper echelons: The organization as a reflection of its top managers[END_REF], and agency theories provide strong arguments on how more diverse boards could lead to superior monitoring and advisory capabilities, and therefore a more strategic involvement in CSR [START_REF] Aggarwal | Board diversity and firm performance: the role of business group affiliation[END_REF][START_REF] Tasheva | Integrating diversity at different levels: Multi-level human capital, social capital, and demographic diversity and their implications for team effectiveness[END_REF].

On the same vein, there is an emerging literature on the board organization and the way boards conduct their roles and their influence on financial and CSR performances. More specifically, the role and the (I) Corporate Social Responsibility: could Ethics rebuild Financial Performance?

I.1 On the confounded link between social performance and financial performance

The debate over the relationship between corporate social performance (CSP) and corporate financial performance (CFP) has dominated the empirical research during the last 40 years [START_REF] Wood | Measuring corporate social performance: a review[END_REF][START_REF] Preston | The corporate social-financial performance relationship[END_REF]and Wood, 1991]. The results of recent empirical studies remain very mixed [START_REF] Rost | Reporting biases in empirical management research: the example of win-win corporate social responsibility[END_REF]. More than 200 empirical studies have been reviewed in previous research [START_REF] Lu | A decades debate on the nexus between corporate social and corporate financial performance: a critical review of empirical studies[END_REF][START_REF] Nelling | Corporate social responsibility and financial performance: the "virtuous circle'' revisited[END_REF][START_REF] Margolis | Does it pay to be good? What a meta-analysis of CSP and CFP can (and cannot) tell us[END_REF][START_REF] Allouche | A meta-analytical investigation of the relationship between corporate social and financial performance[END_REF]Margolis and Walsh, 2003;[START_REF] Orlitzky | Corporate social and financial performance: a meta-analysis[END_REF]. The majority of studies show the existence of a positive association between social performance and financial performance [see among others [START_REF] Nelling | Corporate social responsibility and financial performance: the "virtuous circle'' revisited[END_REF][START_REF] Margolis | Does it pay to be good? What a meta-analysis of CSP and CFP can (and cannot) tell us[END_REF][START_REF] Orlitzky | Corporate social and financial performance: a meta-analysis[END_REF].

In fact, three theoretical models have been developed. The first model describes a positive association between CSP and CFP. The results of several meta-analyses confirm the existence of a positive relationship [START_REF] Rost | Reporting biases in empirical management research: the example of win-win corporate social responsibility[END_REF][START_REF] Endrikat | Making sense of conflicting empirical findings: a meta-analytic review of the relationship between corporate environmental and financial performance[END_REF][START_REF] Albertini | Does environmental management improve financial performance? A meta-analytical review[END_REF][START_REF] Dixon-Fowler | Beyond ''does it pay to be green?'' A meta-analysis of moderators of the CEP-CFP relationship[END_REF]Margolis et al., 2009;and Orlitzky and Swanson, 2008]. This model is based essentially on the theory of social impact [Cornell and Shapiro, 1987] rooted in the stakeholder theory of [START_REF] Freeman | Strategic management: A stakeholder approach[END_REF]. It is based on the assumption that a company creates a competitive advantage through the ability to acquire resources, which leads to the establishment of a long-term synergy between the CSP and the CFP [START_REF] Barney | The attributes of top management teams and sustained competitive advantage[END_REF]. Furthermore, previous studies point out that meeting the needs of the different stakeholders acts as an insurance tool covering reputation risk during crises [Peloza, 2006;Schnietz and Epstein, 2005;Ziglidopoulos, 2001;and Orlitzky and Benjamin, 2001]. Also, [START_REF] Lu | A decades debate on the nexus between corporate social and corporate financial performance: a critical review of empirical studies[END_REF] reported an inconclusive overall result of the CSP-CFP link through a meta-analysis of 84 empirical studies from 2002 to 2011. They find a significant positive relationship between CSP reputation ratings and CFP. Several other studies rooted in the social impact theory and the slack resources theory, such as Waddock and Graves [1997], state that better CFP is a source of social performance. Although companies follow the normative rules of good corporate citizenship, their actual behavior may depend on the resources available. Accordingly, profitability can increase a company's ability to fund social performance projects.

The second model describes a negative link between CSP and CFP [Shane and Spicer, 1983;Freedman and Jaggi, 1982;and Vance, 1975].

Based on the trade-off hypothesis and the hypothesis of the opportunism of managers, CSR decreases financial performance.

The first hypothesis states that the investments in CSR activities may worsen a firm's profitability by inhibiting optimal resource allocation, thus creating a competitive disadvantage [Kang et al., 2010]. The second hypothesis assumes that corporate executives can pursue their private benefits at the expense of shareholders and stakeholders' interests [Weidenbaum and Vogt, 1987, Williamson, 1985, 1967]. One explanation could be that when financial performance is high, managers can seize the opportunity to increase their gains by reducing social spending [Bénabou and Tirole, 2010;and McWilliams et al., 2006].

The third model points out that the costs and benefits of CSR cancel each other out [McWilliams et al., 1999]. In fact, previous studies argue that the link between CSP and CFP may not exist [Germann et al., 2015;Guiral, 2012;[START_REF] Goll | The Moderating Effect of Environmental Munificence and Dynamism on the Relationship Between Discretionary Social Responsibility and Firm Performance[END_REF]McWilliams and Siegel, 2000;and Aupperle et al., 1985]. In fact, CSP-CFP relationship could be powered by many confounding variables, such as environmental and social regulations stringency, R&D expenses, advertising expenditures, labor market conditions, etc. Besides, Allouche and Laroche [2005a] and [START_REF] Orlitzky | Corporate social and financial performance: a meta-analysis[END_REF] show the existence of a virtuous circle, where a financially successful company is prone to be able to spend more on social activities, and better CSP provides a superior long-term economic return.

CSR literature has begun to question the validity of previous studies on the relationship between CSP and CFP since many researchers have displayed discrepancies [Shahzad and Sharfmann, 2017;[START_REF] Crane | Measuring corporate social responsibility and impact: enhancing quantitative research design and methods in business and society research[END_REF][START_REF] Jean | Assessing endogeneity issues in international marketing research[END_REF][START_REF] Endrikat | Making sense of conflicting empirical findings: a meta-analytic review of the relationship between corporate environmental and financial performance[END_REF][START_REF] Schreck | Reviewing the business case for corporate social responsibility: new evidence and analysis[END_REF][START_REF] Garcia-Castro | Does social performance really lead to financial performance? Accounting for endogeneity[END_REF]. For instance, [START_REF] Crane | Measuring corporate social responsibility and impact: enhancing quantitative research design and methods in business and society research[END_REF] and Shahzad and Sharfmann [2017] point out that endogeneity could be the main reason for the ambiguity of the results, specifically in structural equation modeling (SEM) studies using regression analysis to extract causal inferences [START_REF] Jean | Assessing endogeneity issues in international marketing research[END_REF]. This may change the direction and the amplitude of CSR-CFP relationship, and distort results' interpretation [Ketokivi and McIntoch, 2017;[START_REF] Zaefarian | Endogeneity bias in marketing research: problem, causes and remedies[END_REF]. The mixed results on CSP-CFP relationship could be explained to a large extent by the difference in terms of CSR strategies adopted by firms. In fact, CSR practices vary significantly according to the firm's degree of involvement in CSR behavior. Some firms are involved in strategic CSR: they are pioneers and want to achieve a better CSP by going beyond mandatory rules and standards. Some other firms adopt responsive CSR strategies and get involved only on what is legally expected or compliant with stakeholders' demand. Hereafter, we analyze the differences between the two strategies and how they could shape CFP and firms' strategies.

I.2 Strategic CSR versus responsive CSR

Recently, CSR has been directly associated with firms' performance [see among others [START_REF] Vilanova | Exploring the nature of the relationship between CSR and competitiveness[END_REF][START_REF] Porter | The Link Between Competitive Advantage and Corporate Social Responsibility[END_REF]. According to Amin-Chaudhry [2016] and [START_REF] Bagnoli | Selling to socially responsible consumers: Competition and the private provision of public goods[END_REF], firms engage in profit-maximizing CSR, being their lead motivation. Therefore, the proponents of CSR are convinced that investment in CSR enhances the firm's long-term revenue and reputation [START_REF] Gras-Gil | Investigating the relationship between corporate social responsibility and earnings management: Evidence from Spain[END_REF][START_REF] Burke | How corporate social responsibility pays off[END_REF]. In fact, [START_REF] Porter | The Link Between Competitive Advantage and Corporate Social Responsibility[END_REF] point out that when firms integrate CSR activities into their practices, this would help them in achieving competitive advantages. In consequence, according to [START_REF] Zerbini | CSR initiatives as market signals: A review and research agenda[END_REF], [START_REF] Bocquet | CSR, innovation, and firm performance in sluggish growth contexts: A firm-level empirical analysis[END_REF], [START_REF] Porter | The Link Between Competitive Advantage and Corporate Social Responsibility[END_REF], [START_REF] Goyder | Redefining CSR: From the Rhetoric of Accountability to the Reality of Earning Trust[END_REF], and [START_REF] Burke | How corporate social responsibility pays off[END_REF], two opposite views of CSR emerge: 1-Strategic CSR where CSR and the firm's core competencies and resources are aligned. According to [START_REF] Burke | How corporate social responsibility pays off[END_REF], CSR becomes strategic when the company considers social and environmental issues as a high priority and goes beyond the implementation of best practices. It consists of aligning all considerate acts towards people and the natural environment in the organizational context beyond the legal minimum, with the overall objectives and actions of a company. Besides, [START_REF] Bansal | Managing Responsibly in tough economic times: strategic and tactical CSR during the 2008-2009 global Recession[END_REF] argue that the strategic CSR comprises activities with long time horizons and large resource commitments. It also allows the firm to achieve a distinctive position as compared to competitors [Burke and Logdson, 1981].

2-

Responsive CSR where CSR involvement is mainly determined by external expectations and reporting standards. The basic aim of firms is image-building to gain legitimacy in the eyes of their stakeholders [START_REF] Ruggiero | CSR Strategic Approach, Financial Resources and Corporate Social Performance: The Mediating Effect of Innovation[END_REF]. [START_REF] Porter | The Link Between Competitive Advantage and Corporate Social Responsibility[END_REF] define responsive CSR as mitigating existing or potential adverse effects of organizational activities. Indeed, responsive CSR is, most often, associated with a limited level of commitment and more adaptive behavior.

In fact, several relevant theoretical perspectives provide an understanding of the strategic CSR [START_REF] Bhattacharyya | A toolkit for designing firm level strategic corporate social responsibility (CSR) initiatives[END_REF][START_REF] Mcalister | The role of strategic corporate philanthropy in marketing strategy[END_REF][START_REF] Burke | How corporate social responsibility pays off[END_REF].

The first framework is the natural resource-based view proposed by [START_REF] Hart | A natural-resource-based view of the firm[END_REF]. Specifically, [START_REF] Hart | A natural-resource-based view of the firm[END_REF] classifies product stewardship, pollution prevention and sustainable development as three interconnected strategies to support a natural resource-based view. He also points out that achieving sustainable development is the most demanding. It requires good stakeholder integration and good planning. In fact, this framework argues that by integrating sustainability and technological innovation into their strategies, firms could acquire a competitive advantage.

The second framework is the strategic CSR proposed by [START_REF] Burke | How corporate social responsibility pays off[END_REF]. In fact, the authors propose five strategy dimensions to differentiate strategic CSR from responsive CSR: (1) centrality ("the closeness of fit to the firm's mission and objectives"); (2) proactivity ("the degree to which the program is planned in anticipation of emerging social trends and the absence of crisis"); (3) voluntarism ("the scope for discretionary decision-making and the lack of externally imposed compliance requirements"); (4) visibility ("observable, recognizable credit by internal and/or external stakeholders for the firm"); (5) specificity ("the ability to capture private benefits by the firm"). [START_REF] Burke | How corporate social responsibility pays off[END_REF] point out when firms' CSR initiatives meet these features, they are more likely to generate economic benefits. Accordingly, strategic CSR could positively impact firm financial performance.

The third framework is provided by [START_REF] Porter | The competitive advantage of corporate philanthropy[END_REF], 2006[START_REF] Schreck | Reviewing the business case for corporate social responsibility: new evidence and analysis[END_REF]. They argue that strategic CSR goes beyond best practices and provides a competitive advantage, while responsive CSR concerns acting as a good corporate citizen and responding to stakeholders' demands. Accordingly, choosing strategic or responsive CSR produces varied benefits [START_REF] Bocquet | Strategic CSR for innovation in SMEs: Does diversity matter?[END_REF][START_REF] Martinez-Conesa | Corporate social responsibility and its effect on innovation and firm performance: an empirical research in SMEs[END_REF][START_REF] Chang | Proactive and responsive corporate social responsibility: antecedent and consequence[END_REF][START_REF] Bocquet | Are firms with different CSR profiles equally innovative? An empirical analysis with survey data[END_REF]. In fact, if a company combines effectively its resources and expertise with the competitive context, CSR could drive an integral part of its profitability and its competitive positioning [START_REF] Porter | The competitive advantage of corporate philanthropy[END_REF], 2006[START_REF] Schreck | Reviewing the business case for corporate social responsibility: new evidence and analysis[END_REF]. The strategic CSR approach suggested by the authors aims to achieve convergence between social and economic objectives, by requiring firms to use their attributes to meet social needs. Specifically, this model encourages companies to be more selective in terms of CSR engagement.

The final theoretical framework is the stakeholder theory [START_REF] Freeman | Stakeholder theory and "the corporate objective revisited[END_REF]. In fact, managing complex stakeholder relationships is considered as one of the main reasons why a firm should be more concerned about CSR and the opportunities that stakeholders could bring to the business [START_REF] Post | The social responsibility of management: a critique of the shareholder paradigm and defense of stakeholder primacy[END_REF]. The instrumental theory of stakeholders considers CSR as a strategic driver of wealth creation [START_REF] Garriga | Corporate social responsibility theories: Mapping the territory[END_REF][START_REF] Jones | Instrumental stakeholder theory: a synthesis of ethics and economics[END_REF]. Also, according to [START_REF] Jamali | Corporate governance and corporate social responsibility: Synergies and interrelationships[END_REF] and [START_REF] Turker | Measuring corporate social responsibility: a scale development study[END_REF], strategic CSR studies are aligned with the stakeholder perspective of CSR. This could serve as useful guidance for managers in their pursuit of CSR, by providing an easier explanation of stakeholder issues.

All of the above theories on the link between CSP and CFP, provide strong support for the positive association between corporate governance and CSR activities. In fact, the academic debates surrounding this approach argue that the association between good CSR policy and the appropriate behavior of board directors could improve financial profitability [START_REF] Kaufman | Behavioral economics, federalism and the triumph of stakeholder theory[END_REF][START_REF] Choi | Corporate social responsibility and corporate financial performance: evidence from Korea[END_REF][START_REF] Pesqueux | Stakeholder theory in perspective[END_REF][START_REF] Donaldson | Making stakeholder theory whole[END_REF][START_REF] Jones | Convergent stakeholder theory[END_REF][START_REF] Preston | Stakeholder management and organizational wealth[END_REF][START_REF] Sternberg | The stakeholder concept: a mistaken doctrine, Foundation for Business Responsibilities[END_REF][START_REF] Freeman | Strategic management: A stakeholder approach[END_REF]. For instance, according to [START_REF] Cuervo | Corporate governance mechanisms: A plea for less code of good governance and more market control[END_REF], corporate governance is a specific mechanism where the board of directors plays a relevant role in advising management on taking the most appropriate decisions and ensuring the long-term viability of the company. Consequently, the decisions taken by the board could lead to the possible implementation of CSR policies [START_REF] Ingley | The financial crisis, investor activists and corporate strategy: will this mean shareholders in the boardroom?[END_REF] and influence, therefore, CFP. Moreover, [START_REF] Choi | Corporate social responsibility and corporate financial performance: evidence from Korea[END_REF] argue that the level of effort in terms of CSR depends on the relative importance given by the company to its interest groups. The company establishes an order of priority amongst them and favors those who are best positioned [START_REF] Surroca | Corporate responsibility and financial performance: The role of intangible resources[END_REF]. Thus, it becomes imperative to introduce good corporate governance recommendations as an important element of CSR. In the next section, we analyze how governance features could be influential to different extents on the degree of involvement in CSR strategies. Specifically, we focus on board characteristics.

(II) Corporate Governance and CSR

Research and scholarship on board diversity have been one of the most prolific topics in recent years, appearing as one of the most significant current themes in corporate governance research [START_REF] Tasheva | Integrating diversity at different levels: Multi-level human capital, social capital, and demographic diversity and their implications for team effectiveness[END_REF][START_REF] Jizi | The Influence of Board Composition on Sustainable Development Disclosure[END_REF][START_REF] Harjoto | Board diversity and corporate social responsibility[END_REF][START_REF] Hafsi | Boardroom diversity and its effect on social performance: conceptualization and empirical evidence[END_REF][START_REF] Ben-Amar | What makes better boards? A closer look at diversity and ownership[END_REF][START_REF] Mahadeo | Board Composition and Financial Performance: Uncovering the Effects of Diversity in an Emerging Economy[END_REF][START_REF] Bear | The impact of board diversity and gender composition on corporate social responsibility and firm reputation[END_REF][START_REF] Kang | Corporate governance and board composition: Diversity and independence of Australian boards[END_REF].

The prior literature has focused on the role of board diversity on cognitive impacts such as creativity, innovation and the generation of new ideas [START_REF] Tasheva | Integrating diversity at different levels: Multi-level human capital, social capital, and demographic diversity and their implications for team effectiveness[END_REF]Adams et al., 2015;Miller and Triana, 2009;[START_REF] Kang | Corporate governance and board composition: Diversity and independence of Australian boards[END_REF][START_REF] Ruigrok | Nationality and gender diversity on Swiss corporate boards[END_REF][START_REF] Carter | Corporate governance, board diversity, and firm value[END_REF]and Robinson and Dechant, 1997]. These studies show that diversity fosters creativity, innovation, and independence of thought processes. For instance, [START_REF] Carter | Corporate governance, board diversity, and firm value[END_REF] argue that board diversity allows a company to better understand her marketplace, which improves market penetration ability.

According to several studies [START_REF] Mahadeo | Board Composition and Financial Performance: Uncovering the Effects of Diversity in an Emerging Economy[END_REF][START_REF] Kang | Corporate governance and board composition: Diversity and independence of Australian boards[END_REF][START_REF] Erhardt | Board of director diversity and firm financial performance[END_REF]Milliken and Martin, 1996], board diversity refers to the heterogeneity of a board across different demographic characteristics such as age, educational level, gender, and nationality, as well as the heterogeneity across different structural characteristics such as duality and independence. For instance, [START_REF] Mahadeo | Board Composition and Financial Performance: Uncovering the Effects of Diversity in an Emerging Economy[END_REF] and [START_REF] Carter | Corporate governance, board diversity, and firm value[END_REF] argue that diversity can be considered as an ethical objective, which brings to the company several advantages, such as greater creativity, a better understanding of the market, and better problemsolving. Therefore, it provides a competitive advantage for the company, as well as several beneficial long-term results [START_REF] Erhardt | Board of director diversity and firm financial performance[END_REF][START_REF] Siciliano | The relationship of board member diversity to organizational performance[END_REF].

Furthermore, Hemmingway and Maclagan [2004] argue that individuals' beliefs and values could influence board discussion related to CSR, as there is no mandatory standard for CSR [START_REF] Deegan | Stakeholder influence on corporate reporting: An exploration of the interaction between WWF-Australia and the Australian minerals industry[END_REF]. Also, [START_REF] Hambrick | The influence of top management team heterogeneity on firms' competitive moves[END_REF] and [START_REF] Nielsen | The contribution of women on boards of directors: Going beyond the surface[END_REF] put forward that, in high uncertainty contexts, diverse teams are more successful, while, in stable contexts, less diverse teams achieve better performance.

In fact, many theories have highlighted the effective role of board members to implement effective CSR strategies. For instance, the upper echelons theory [START_REF] Hambrick | Upper echelons: The organization as a reflection of its top managers[END_REF] provides strong arguments on how more diverse boards could lead to superior monitoring, and thus, more strategic involvement in CSR [START_REF] Aggarwal | Board diversity and firm performance: the role of business group affiliation[END_REF][START_REF] Tasheva | Integrating diversity at different levels: Multi-level human capital, social capital, and demographic diversity and their implications for team effectiveness[END_REF]. This theory suggests that the characteristics of directors, such as age, gender, educational level, knowledge, skills, values, professional experience, and tenure, influence their interpretations of the situations they face, which affects, therefore, their strategic choices [Hambrick, 2007].

Based on agency theory [START_REF] Jensen | Theory of the firm: Managerial behavior, agency costs and ownership structure[END_REF], one of the main functions of a board of directors is to act as fiduciaries of shareholders by monitoring top management on behalf of shareholders. According to [START_REF] Jo | Corporate governance and firm value: The impact of corporate social responsibility[END_REF]Harjoto [2011, 2012], the effectiveness of corporate governance practices is closely related to the board's composition. For instance, corporate transparency practices are determined by board directors to improve management practices and to ensure the involvement of a company in more ethical projects.

Furthermore, another important theoretical perspective for diversity is the resource dependence theory [START_REF] Pfeffer | The External Control of Organisations: A Resource Dependence Perspective[END_REF]]. In fact, several studies point out that board diversity allows the firm to acquire critical resources, policy advice, knowledge, and networks, and to widen the range of choices when making strategic decisions [Locke and Reddy, 2015;[START_REF] Taljaard | Board diversity and financial performance: A graphical time-series approach[END_REF][START_REF] Al-Musalli | Intellectual capital performance and board characteristics of GCC banks[END_REF][START_REF] Goodstein | The effects of board size and diversity on strategic change[END_REF]Pfeffer, 1972;[START_REF] Pfeffer | The External Control of Organisations: A Resource Dependence Perspective[END_REF]. According to [START_REF] Bear | The impact of board diversity and gender composition on corporate social responsibility and firm reputation[END_REF], diversity enhances the internal and external resources of the board, such as the new skills and competencies. This helps companies to better respond to stakeholders' expectations. They become more sensitive to CSR issues due to the variety of resources given by board diversity [START_REF] Davis | Corporations and economic inequality around the world: The paradox of hierarchy[END_REF]Susan Vinnicombe et al., 2003;[START_REF] Pfeffer | The External Control of Organisations: A Resource Dependence Perspective[END_REF].

II.1 Board diversities: diversity in boards and diversity of boards

Much of the prior literature has focused on the impact of board composition on a firm's behavior [START_REF] Lehn | Determinants of the size and composition of US corporate boards: 1935-2000[END_REF][START_REF] Linck | The determinants of board structure[END_REF][START_REF] Fich | Are busy boards effective monitors?[END_REF]. The level of diversity could be considered as one of the key aspects of board composition.

Prior research on board diversity distinguishes between structural and demographic diversity of boards [START_REF] Aggarwal | Board diversity and firm performance: the role of business group affiliation[END_REF][START_REF] Jizi | The Influence of Board Composition on Sustainable Development Disclosure[END_REF][START_REF] Harjoto | Board diversity and corporate social responsibility[END_REF][START_REF] Hafsi | Boardroom diversity and its effect on social performance: conceptualization and empirical evidence[END_REF]. The structural diversity of boards is linked to dissimilarities in board attributes, which are related to boards' formal structure, such as size, the non-separation between management and control functions, board independence, and board committees [START_REF] Tasheva | Integrating diversity at different levels: Multi-level human capital, social capital, and demographic diversity and their implications for team effectiveness[END_REF]. Demographic diversity, however, is given by the individual attributes of directors such as gender, age, nationality, educational level, educational background, multiple directorships, culture, tenure, nationality, and experience. [START_REF] Hafsi | Boardroom diversity and its effect on social performance: conceptualization and empirical evidence[END_REF] highlight that the structural diversity of boards does not allow to differentiate among firms or to explain their differences, while demographic diversity does. Table 1.1 summarizes the findings from this literature review. [

Key

II.1.1. Diversity of boards

Diversity of boards stems from the structural differences that could exist between boards. It has several attributes. First, board size is considered as a critical factor that determines the effectiveness of board oversight. However, the literature provides no consensus regarding the effect of board size on firm performance. The resource dependency theory holds that large boards are likely to have better information and more knowledge, which allows them to provide more oriented advice on strategic decisions [START_REF] De Villiers | The effect of board characteristics on firm environmental performance[END_REF][START_REF] Siciliano | The relationship of board member diversity to organizational performance[END_REF]Provan, 1980;andPfeffer, 1972, 1973]. For instance, Kabir et al. [2017] put forward that large boards can increase the firm's involvement in CSR investments and have a better CSR performance as they have more resources provided for consulting and monitoring roles. Moreover, prior studies show that large boards are more likely to constitute a specific social capital and have more effective communication. Therefore, they are prone to contribute more to the efficiency of the ethical decision-making process than small boards, which could lead to a better CSR performance [Hillman et al., 2001;Clarkson 1995;[START_REF] Pfeffer | The External Control of Organisations: A Resource Dependence Perspective[END_REF]. For instance, the mean board size of a firm is around 9 members in European firms and US firms [START_REF] Haque | European firms' corporate biodiversity disclosures and board gender diversity from 2002 to 2016[END_REF][START_REF] Madden | Drivers of selectivity in family firms: Understanding the impact of age and ownership on CSR[END_REF]. Table 1.2 presents descriptive statistics of the study of [START_REF] Beji | Board Diversity and Corporate Social Responsibility: Empirical Evidence from France[END_REF] on the association between boards' characteristics and globally CSR and specific areas of CSR, conducted on French companies listed on the SBF 120 d index between 2003 However, the agency theory holds that agency problems can become more severe with larger boards, specifically when they suffer from coordination and communication problems [Hermalin and Weisbach, 2003;Bushman and Smith, 2001;and Yermack, 1996]. In fact, it is easier for the CEO to control and influence the smaller boards as they can reach consensus more easily in comparison with large boards [Cheng, 2008]. Another board characteristic is the presence of independent directors on boards [Hermalin and Weisbach, 2003]. [START_REF] Jo | Corporate governance and firm value: The impact of corporate social responsibility[END_REF] point out that independent directors have stronger stakeholder orientation and better management quality, which leads to a successful CSR implementation [Shaukat et al., 2015;Li et al., 2012;[START_REF] Jo | Corporate governance and firm value: The impact of corporate social responsibility[END_REF]Ho and Wong, 2001]. Also, Independent directors are prone to reduce agency conflicts and to ensure effective monitoring. In the same vein, Adams and Ferreira [2009] and Walsh and Seward [1990] point out that independent directors help to monitor executives' agency behavior, as they tend to check managers' self-serving decisions and to solve attendance problems on the board.

Also, previous studies argue that the duality structure on the board is prone to decrease corporate investment in CSR. According to [START_REF] Jizi | Corporate governance and corporate social responsibility disclosure: Evidence from the US banking sector[END_REF] and Surroca and Tribo [2008], the concentration of management and control functions in the CEO's hands is likely to have negative impacts on the engagement in CSR activities. Furthermore, in line with agency theory, duality increases the CEO power and, therefore, CEO-chair could enjoy private benefits at the expense of CSR investments. In fact, CEOs who also act as the chair may pursue opportunistic strategies to protect their interests at the expense of shareholders [START_REF] Jizi | Corporate governance and corporate social responsibility disclosure: Evidence from the US banking sector[END_REF][START_REF] Firth | Ownership, two-tier board structure, and the informativeness of earnings-Evidence from China[END_REF]. They are also prone to prefer short term financial projects and to marginalize valueenhancing projects, specifically long-term projects such as CSR ones [Surroca and Tribo, 2008;[START_REF] Firth | Ownership, two-tier board structure, and the informativeness of earnings-Evidence from China[END_REF]. Focusing only on the diversity of boards does not help to fully assess the most influential factors of CSP. We need also to address its interaction with other forms of diversity, such as diversity in boards.

II.1.2 Diversity in boards

There is emerging literature, specifically on cognitive governance, on the influence of board members on CSP. It shows that, under specific conditions, the diversity of directors 'profiles could be a valuable resource for the business, particularly on CSR area [see among others [START_REF] Conyon | Firm performance and boardroom gender diversity: A quantile regression approach[END_REF][START_REF] Rodriguez-Ariza | Consequences of earnings management for corporate reputation: Evidence from family firms[END_REF][START_REF] Pucheta-Martínez | Corporate governance, female directors and quality of financial information[END_REF]and Boulouta, 2013].

Gender diversity on boards has attracted increasing interest in the last years. According to the social role theory [START_REF] Eagly | Sex Differences in Social Behaviour: A Social-Role Interpretation[END_REF][START_REF] Eagly | Explaining sex differences in social behavior: A meta-analytic perspective[END_REF], women are more likely to be oriented toward others' welfare, more concerned with personal relationships, and more socially skilled than men. They are prone to show communal qualities, while men are likely to display agentic qualities [START_REF] Eagly | Explaining sex differences in social behavior: A meta-analytic perspective[END_REF]. Moreover, in line with the cognitive moral reasoning theory [START_REF] Kohlberg | Stage and sequence: The cognitive development approach to socialization[END_REF](Kohlberg, , 1976]], women and men are different in terms of moral reasoning [START_REF] Jaffee | Gender differences in moral orientation: A metaanalysis[END_REF]]. In fact, previous studies show that women have higher cognitive moral reasoning scores and more ethical perceptions than men [START_REF] Elm | Determinants of moral reasoning: Sex role orientation, gender, and academic factors[END_REF][START_REF] Eynon | Factors that influence the moral reasoning abilities of accountants: Implications for universities and the profession[END_REF][START_REF] Forte | Business ethics: A study of the moral reasoning of selected business managers and the influence of organizational ethical climate[END_REF]. Also, consistent with the upper echelons' theory [START_REF] Hambrick | Upper echelons: The organization as a reflection of its top managers[END_REF], women and men on board display different cognitive features.

They have different norms, attitudes, perspectives, experiences, and knowledge [START_REF] Sundarasen | Board composition and corporate social responsibility in an emerging market[END_REF][START_REF] Pelled | Exploring the black box: An analysis of work group diversity, conflict and performance[END_REF]. For instance, prior studies show that female directors could bring to light new perspectives, which improves, therefore, the governance quality [START_REF] Conyon | Firm performance and boardroom gender diversity: A quantile regression approach[END_REF][START_REF] Pucheta-Martínez | Corporate governance, female directors and quality of financial information[END_REF][START_REF] Krishnan | Getting to the bottom line: An exploration of gender and earnings quality[END_REF]. Furthermore, in line with the resource dependence theory [START_REF] Pfeffer | The External Control of Organisations: A Resource Dependence Perspective[END_REF] and the social identity theory [START_REF] Ashforth | Social identity theory and the organization[END_REF], female directors are more engaged in social activities and more likely to undertake non-profit activities. Besides, they could provide new perspectives and many resources to the board which improves, therefore, the governance quality [START_REF] Conyon | Firm performance and boardroom gender diversity: A quantile regression approach[END_REF][START_REF] Rodriguez-Ariza | Consequences of earnings management for corporate reputation: Evidence from family firms[END_REF][START_REF] Pucheta-Martínez | Corporate governance, female directors and quality of financial information[END_REF]Boulouta, 2013;[START_REF] Zhang | Institutional Dynamics and Corporate Social Responsibility (CSR) in an Emerging Country Context: Evidence from China[END_REF][START_REF] Post | Green governance: Boards of directors' composition and environmental corporate social responsibility[END_REF][START_REF] Nielsen | The contribution of women on boards of directors: Going beyond the surface[END_REF][START_REF] Krishnan | Getting to the bottom line: An exploration of gender and earnings quality[END_REF]. Previous studies put forward that socially responsible firms are associated with a higher percentage of female directors [START_REF] Harjoto | Board diversity and corporate social responsibility[END_REF][START_REF] Hafsi | Boardroom diversity and its effect on social performance: conceptualization and empirical evidence[END_REF][START_REF] Zhang | Institutional Dynamics and Corporate Social Responsibility (CSR) in an Emerging Country Context: Evidence from China[END_REF][START_REF] Carter | Corporate governance, board diversity, and firm value[END_REF]. For instance, [START_REF] Carter | Corporate governance, board diversity, and firm value[END_REF] find that gender-diverse boards perform better than less diverse ones. Further, Rodriguez Ariza et al.

[2016], [START_REF] Braun | Going green: women entrepreneurs and the environment[END_REF], and [START_REF] Nielsen | The contribution of women on boards of directors: Going beyond the surface[END_REF] point out that female directors are prone to be more engaged in green activities and more concerned about environmental issues than men. However, low gender quotas cannot influence CSP. For example, [START_REF] Post | Green governance: Boards of directors' composition and environmental corporate social responsibility[END_REF] show that environmental strengths scores increases in the presence of at least three female members on the board.

In fact, using a dataset of listed firms from India, China, and Russia over the period 2007-2014[START_REF] Saeed | Impact of board gender diversity on dividend payments: Evidence from some emerging economies[END_REF] find that board gender diversity had increased in each country. Specifically, gender diversity on boards had increased from 5.6% to 10.3% in India, and 4.7% to 9.5% for Russia. The highest increase has been noticed in China where the percentage of female directors has more than doubled (from 7.6% to 14.4%). This could be explained by many reasons such as globalization and the proliferation of cross-border trade, communities' pressure (feminist groups), the emerging of standards and norms for acceptable governance practices conducted by international organizations (the UN and the OECD). In addition, there is a regulatory pressure of governments all over the world to increase gender diversity. Moreover, between 2009 and 2011, the GMI Ratings' (2012) Women on Boards Survey f shows low percentages of women on boards: only 12.9% in Germany, and 12.6% in the USA. In France, the parliament introduced in 2011, a gender quota law to have more gender-balanced boards: the gender quota law of Copé-Zimmermann. French listed firms must appoint at least 20 % of women to their boards by the end of 2010 and at least 40 % by the end of 2017". Consequently, many firms have suddenly increased gender diversity in their boards to comply with this law.

Another dimension of diversity in boards is the director's age. Prior studies suggest that age diversity enhances CSR performance [START_REF] Ferrero-Ferrero | Board Diversity: An Empirical Study in the Board of Directors[END_REF][START_REF] Hafsi | Boardroom diversity and its effect on social performance: conceptualization and empirical evidence[END_REF][START_REF] Post | Green governance: Boards of directors' composition and environmental corporate social responsibility[END_REF]Harrison and[START_REF] Harrison | What's the difference? Diversity constructs as separation, variety, or disparity in organizations[END_REF]. According to [START_REF] Ouma | Effect of Age Diversity of Board Members on Performance of Non-Governmental Organizations in Kenya[END_REF], age diversity could reflect directors' knowledge, experience, and openness to new ideas. Besides, [START_REF] Ferrero-Ferrero | Board Diversity: An Empirical Study in the Board of Directors[END_REF] argue that age diversity helps to avoid the threat of "narrow group thinking". Regarding the influence of age diversity on CSR performance, results are mixed. [START_REF] Hafsi | Boardroom diversity and its effect on social performance: conceptualization and empirical evidence[END_REF] and Kets de Vries et al. [1984] argue that as directors mature, their generational behavior increases, and therefore, older directors are more likely to be sensitive to society. However, other studies document a negative association between the director's age and CSR performance. For instance, [START_REF] Post | Green governance: Boards of directors' composition and environmental corporate social responsibility[END_REF] argue that younger directors show more concern about environmental issues and tend to be more sensitive to ethical issues.

Also, the presence of foreign directors could be a valuable resource for businesses, specifically on CSR areas [START_REF] Hafsi | Boardroom diversity and its effect on social performance: conceptualization and empirical evidence[END_REF][START_REF] Tihanyi | The effect of cultural distance on entry mode choice, international diversification, and MNE performance: A metaanalysis[END_REF][START_REF] Oxelheim | The impact of foreign board membership on firm value[END_REF][START_REF] Eskeland | Moving to Greener Pastures? Multinationals and the Pollution Haven Hypothesis[END_REF]. For instance, according to [START_REF] Tihanyi | The effect of cultural distance on entry mode choice, international diversification, and MNE performance: A metaanalysis[END_REF] and [START_REF] Eskeland | Moving to Greener Pastures? Multinationals and the Pollution Haven Hypothesis[END_REF], foreign directors are more concerned about philanthropic contributions and local social development. Most often, they have access to broader social networks, diversified and international expertise, and may prefer using technologies producing less waste and pollution. In addition, foreign directors could take advantage of their cultural values on the role of corporations in society to benefit the business [see among others Hafsi and[START_REF] Hafsi | Boardroom diversity and its effect on social performance: conceptualization and empirical evidence[END_REF][START_REF] Oxelheim | The impact of foreign board membership on firm value[END_REF][START_REF] Oxelheim | The impact of foreign board membership on firm value[END_REF].

Another dimension of diversity is the educational level diversity [START_REF] Rupley | Governance, media and the quality of environmental disclosure[END_REF][START_REF] Goll | The Moderating Effect of Environmental Munificence and Dynamism on the Relationship Between Discretionary Social Responsibility and Firm Performance[END_REF][START_REF] Hillman | Boards of directors and firm performance: Integrating agency and resource dependence perspectives[END_REF][START_REF] Geletkanycz | Bound by the past? Experience-based effects on commitment to the strategic status quo[END_REF]. For instance, [START_REF] Geletkanycz | Bound by the past? Experience-based effects on commitment to the strategic status quo[END_REF] and [START_REF] Hambrick | Upper echelons: The organization as a reflection of its top managers[END_REF] argue that directors with high educational levels contribute to the firm's success, as they have a better capacity to benefit from opportunities and to learn more about new trends. Moreover, [START_REF] Finkelstein | Strategic Leadership: Theory and Research on Executives, Top Management Teams and Boards[END_REF], [START_REF] Goll | The Moderating Effect of Environmental Munificence and Dynamism on the Relationship Between Discretionary Social Responsibility and Firm Performance[END_REF]; and Grimm and [START_REF] Smith | Organizational information processing, competitive responses, and performance in the U.S. domestic airline industry[END_REF] suggest that high-educated directors are more likely to adjust their strategies in response to deregulation and other changes, and display different and rational decision-making processes, in comparison with other directors. Furthermore, several studies argue that high-educated directors tend to be more concerned about environmental issues and international markets, to better understand problems that may affect the environment [START_REF] Shahgholian | The Effect of Board Roles on Firm Environmental Governance[END_REF][START_REF] Ewert | Standing for Where You Sit: An Exploratory Analysis of the Relationship between Academic Major and Environment Beliefs[END_REF][START_REF] Hines | Analysis and synthesis of research on responsible environmental behavior: A meta-analysis[END_REF]. For instance, [START_REF] Shahgholian | The Effect of Board Roles on Firm Environmental Governance[END_REF] put forward that highly educated directors are more likely to help the board to develop environmental activities, as they have more knowledge of environmental issues.

Previous research also shows evidence that multiple directorships could be a key determinant of the involvement in CSR activities [START_REF] Rupley | Governance, media and the quality of environmental disclosure[END_REF]. In fact, according to [START_REF] Rupley | Governance, media and the quality of environmental disclosure[END_REF], directors who are sitting on multiple boards could bring to the board information about unfamiliar practices, based on their experience on other firms. Therefore, they could help the company to adopt policies of other companies, and increase environmental performance. They are more likely to have access to more information about environmental initiatives and to help to shape more proactive environmental strategies [START_REF] De Villiers | The effect of board characteristics on firm environmental performance[END_REF]. Having different experiences could increase CSR sensitivity directors with multiple directorships. Accordingly, they could show more ethical behavior and become more involved in CSR practices.

Finally, despite the fact that there is a growing number of studies on diversity in boards and diversity of boards, to the best of our knowledge, the interaction between the two forms of diversity and how it could influence CSR is not yet fully explored.

II.2 CSR performance and CSR committees

According to [START_REF] Godos-Díez | Relationship between Corporate Social Responsibility (CSR) and Internationalisation Strategies: A Descriptive Study in the Spanish Context[END_REF], companies establish specialized committees to better deal with a wide range of board functions. For instance, firms concerned about being socially and environmentally responsible, create CSR committees (CSRC) in charge of CSR strategies. Several emerging papers show that companies establish CSRCs to their transparency in the field of CSR and their commitment towards sustainable development [Hussain et al., 2018a;[START_REF] Mallin | Board reputation attributes and corporate social performance: an empirical investigation of the US Best Corporate Citizens[END_REF][START_REF] Eccles | The impact of a corporate culture of sustainability on corporate behavior and performance[END_REF]. These committees are prone to shape the strategies required to promote and implement firms' CSR initiatives and to decrease CSR risks [Hussain et al., 2018a;[START_REF] Peters | The association between sustainability governance characteristics and the assurance of corporate sustainability reports[END_REF][START_REF] Rodrigue | Is environmental governance substantive or symbolic? An empirical investigation[END_REF]. Prior literature shows that the presence of CSRCs on boards increases CSR performance [START_REF] Cucari | Diversity of board of directors and environmental social governance: Evidence from Italian listed companies[END_REF][START_REF] Helfaya | Do board's corporate social responsibility strategy and orientation influence environmental sustainability disclosure? UK Evidence[END_REF][START_REF] Bagh | The Corporate Social Responsibility and Firms' Financial Performance: Evidence from Financial Sector of Pakistan[END_REF][START_REF] Peters | The association between sustainability governance characteristics and the assurance of corporate sustainability reports[END_REF][START_REF] Walls | Corporate governance and environmental performance: Is there really a link?[END_REF][START_REF] Mallin | Board reputation attributes and corporate social performance: an empirical investigation of the US Best Corporate Citizens[END_REF][START_REF] Mallin | Board reputation attributes and corporate social performance: an empirical investigation of the US Best Corporate Citizens[END_REF]. For instance, [START_REF] Sánchez | Board independence and GRI-IFC Performance Standards: the mediating effect of the CSR committee[END_REF] and [START_REF] Bagh | The Corporate Social Responsibility and Firms' Financial Performance: Evidence from Financial Sector of Pakistan[END_REF] point out that the existence of CSRCs allows for a better understanding of the key strategic problems facing the board of directors. CSRCs aim to promote CSR strategies and provide new incentives to CEOs to get the business actively involved in CSR projects. The survey of the literature shows that CSRCs could be also called environmental committees [START_REF] Liao | Gender diversity, board independence, environmental committee and greenhouse gas disclosure[END_REF][START_REF] Walls | Corporate governance and environmental performance: Is there really a link?[END_REF][START_REF] Adnan | Do culture and governance structure influence CSR reporting quality: Evidence from China, India, Malaysia and the United Kingdom[END_REF]. Environmental committees are established to increase the firm's proactivity in handling environmental issues [START_REF] Walls | Corporate governance and environmental performance: Is there really a link?[END_REF]. For instance, using a sample of 4,013 firm-year observations from listed companies in 13 European countries from 2002 to 2016, [START_REF] Haque | European firms' corporate biodiversity disclosures and board gender diversity from 2002 to 2016[END_REF] find that 63% of the firms maintain CSR committee of the board. Moreover, [START_REF] Eberhardt-Toth | Who should be on a board corporate social responsibility committee?[END_REF] points out that, in 2012, the proportion of firms with CSRCs on boards represents 25.42% in UK, and 16.38% in the USA.

The state of art on CSRC composition shows that most of the current studies have focused on the analysis of structural and demographic characteristics of CSRC members.

II.2.1 Structural characteristics of CSRC

Turning to the CSRC attributes, to the best of our knowledge, few studies have investigated the CSRC composition. For instance, some papers have analyzed how the presence of independent members in CSRC could affect CSR performance [START_REF] Del Valle | Corporate social responsibility and sustainability committee inside the board[END_REF][START_REF] Adams | The Role of Boards of Directors in Corporate Governance: A Conceptual Framework and Survey[END_REF]. According to [START_REF] Lovdal | Public responsibility committees of the board[END_REF], in order to maintain a critical view of management operations, 80% of CSRC's directors should be independent. Also, Danvila del [START_REF] Del Valle | Corporate social responsibility and sustainability committee inside the board[END_REF], and [START_REF] Aboody | Information asymmetry, R&D, and insider gains[END_REF], independent members of CSRCs are more likely to ensure effective monitoring and better management quality, as they provide more objective feedback on firms' activities. Accordingly, their presence could prevent stakeholders from the opportunistic behavior of managers, which could enhance social performance. Another set of papers shows that the presence of independent directors could decrease CSR performance. One explanation is that independent members could suffer from a lack of information about the day-to-day operations of the business and the company's strategies [START_REF] Adams | The Role of Boards of Directors in Corporate Governance: A Conceptual Framework and Survey[END_REF]. They may face limited-access to firm-specific information. Their decisions could be, therefore, largely based on information provided by the managers [START_REF] De Villiers | The effect of board characteristics on firm environmental performance[END_REF][START_REF] Donnelly | Board structure, ownership, and voluntary disclosure in Ireland[END_REF][START_REF] Adams | A theory of friendly boards[END_REF].

Another interesting feature of CSRC is CEO membership. In fact, [START_REF] Graham | CEO power and board dynamics[END_REF] argue that the CEO is prone to care more about profitable projects than environmental and social projects, and could, therefore, avoid risks and uncertainty related to CSR activities. Also, Danvila del [START_REF] Del Valle | Corporate social responsibility and sustainability committee inside the board[END_REF] point out that it could be difficult to challenge the CEO on CSR issues if he or she is a member of the CSRC, which may affect negatively CSR performance. According to the agency theory, CEOs could adopt an opportunistic behavior to increase their private benefits at the expense of shareholders. Powerful CEOs could be tempted to manipulate information on CSR investments, particularly when they are entrenched [START_REF] Bebchuk | The CEO pay slice[END_REF][START_REF] Bartov | Private information, earnings manipulations and executive stock-option exercises[END_REF][START_REF] Aboody | Information asymmetry, R&D, and insider gains[END_REF]. In fact, they could influence committees' discussions, by sharing their personal views in order to maximize their benefits [Clune Richard et al., 2014].

Some studies have focused on the relationship between CSRC size and CSR performance. According to [START_REF] Golden | When will boards influence strategy? Inclination × power = strategic change[END_REF], significant strategic changes are related to smaller board sizes. This idea can be extended to the CSRC. In fact, strong strategic changes are needed to achieve CSR performance. In a small committee, each director's decision is less likely to depend on the other director's decision. Therefore, directors make more individual effort to fulfill their responsibilities. However, in line with the resource dependence theory [START_REF] Pfeffer | The External Control of Organisations: A Resource Dependence Perspective[END_REF], more directors imply more resources and larger networks, which could be valuable to enhance CSR strategies [START_REF] Mangena | The effect of audit committee shareholding, financial expertise and size on interim financial disclosures[END_REF][START_REF] Defond | Audit research after Sarbanes-Oxley[END_REF]. Additionally, [START_REF] Bedard | The effect of audit committee expertise, independence, and activity on aggressive earnings management[END_REF] put forward that a larger committee has the necessary strength, diversity of expertise and views to ensure appropriate monitoring' which leads to higher CSR performance.

Not only the CSRC size has been discussed in the literature but also the committee functioning has been analyzed as it could matter in CSR.

For instance, previous studies show that the number of meetings organized could be considered as a proxy for directors' monitoring effort [START_REF] Nurulyasmin | Board Independence and Corporate Social Responsibility (CSR) Reporting in Malaysia[END_REF][START_REF] Ponnu | Board independence and corporate performance: Evidence from Malaysia[END_REF][START_REF] Vafeas | Board meeting frequency and firm performance[END_REF]. According to [START_REF] Vafeas | Board meeting frequency and firm performance[END_REF], meetings' frequency could be a remedy to asymmetric information problems. For instance, [START_REF] Nurulyasmin | Board Independence and Corporate Social Responsibility (CSR) Reporting in Malaysia[END_REF] and [START_REF] Ponnu | Board independence and corporate performance: Evidence from Malaysia[END_REF] put forward that with a high-frequency meeting committee, directors could be more informed about existing and appropriate strategies. Accordingly, they become more likely to use their knowledge to help managers to enhance their decision-making process. A higher frequency of board meetings allows the directors to better carry out their duties in line with shareholders' expectations [see among others [START_REF] Salim | Does corporate governance affect Australian banks' performance?[END_REF][START_REF] Chou | Attendance of board meetings and company performance: Evidence from Taiwan[END_REF].

Another interesting feature of CSRC functioning is directors' assiduity in CSRC meetings. In fact, [START_REF] Huilong | Removing Vacant Chairs: Does Independent Directors' Attendance at Board Meetings Matter?[END_REF] argue that directors' assiduity shows the level of commitment to the job, which could have an impact on a firm's corporate governance. This could enhance information sharing between firm management and CSRC, which may increase CSR performance.

II.2.2 Demographic characteristics

Regarding the demographic characteristics of CSRC, very little evidence has been provided. In fact, the most discussed feature is the presence of female members on CSRC. If gender diversity is valuable in boardrooms, there is some evidence that it could be also valuable in CSRCs: Appointing more female members on CSRCs on committees could be another way for directors to get actively involved in CSR activities and to effectively enhance social and financial performances [START_REF] Pucheta-Martínez | Corporate governance, female directors and quality of financial information[END_REF][START_REF] Krishnan | Getting to the bottom line: An exploration of gender and earnings quality[END_REF][START_REF] Carter | Corporate governance, board diversity, and firm value[END_REF]. For instance, Pucheta-Martínez et al. [2016] and [START_REF] Carter | Corporate governance, board diversity, and firm value[END_REF] point out that female directors are more prone to improve the performance of the CSRC, by increasing the creativity and innovation of the committee. In fact, they could bring important resources such as skills and constituencies and external networks [START_REF] Krishnan | Getting to the bottom line: An exploration of gender and earnings quality[END_REF]. Besides, previous studies also show that the significant roles of boards are usually attributed to the more interactive and participative style of leadership by female directors [START_REF] Conyon | Firm performance and boardroom gender diversity: A quantile regression approach[END_REF][START_REF] Elstad | Women on corporate boards: key influencers or tokens?[END_REF]. The firms rely more on female directors' skills, especially when the chair committee is a woman [Peterson and Philpot, 2007;[START_REF] Mattis | Women corporate directors in the United States[END_REF]. To the best of our knowledge, there is a huge gap in the literature on the influence of other demographic features on CSRC such as age, the educational level, the professional experience and ethnic diversity on social performance.

(III) Discussion

The current chapter sheds light on urgent and critical issues on boards and their functioning when it comes to CSR-related concerns.

From a managerial perspective, it shows the relevance of the board composition in CSR strategies. Boards have to prioritize structural and demographic diversities to bring new meaningful insights specifically in terms of more ethical behavior. Increasing diversity could boost overall corporate visibility and develop a more proactive and comprehensive strategy and orientation.

First, the emerging studies on the Board-CSR relationship show how the diversity of boards and diversity in boards could help the firm to achieve a double-target: improving the governance quality and getting better social and financial performances.

In practice, there is a huge debate on the way to achieve more diverse-balanced boards. Some studies stand for the role of regulation to increase diversity in boards (like for example, gender quota law). However, this could lead to the increase of multiple directorships and raises, therefore, several questions on the extent to which directors sitting on different boards could be and stay independent. For instance, in France and Spain, as the pool of business women candidates and the need to urgently comply with the law, many firms have appointed non-business women members to their boards. Some non-regulation defenders highlight the side effects of appointing nonexpert profiles and its influence on the business. Accordingly, as a response, many countries, have preferred to rely on recommendations and voluntary quotas, instead of laws to increase the involvement of minorities in top management positions.

Besides, when minority groups are not supported in their choices, this could worsen the board dynamics, and slower therefore, the decision-making process. For instance, [START_REF] Erkut | Critical mass: does the number of women on a corporate board make a difference[END_REF] show that when only one or two female members are appointed to the board, they cannot influence the boards' decisions. A critical number of female board members is needed in order to exert a positive influence on the boards' decisions.

Furthermore, women are more likely than men to serve in precarious management positions and continue to be underrepresented in leadership positions. This is explained by the "glass ceiling" that prevents women from gaining access to such positions [START_REF] Singh | Why so few women directors in top UK boardrooms? Evidence and theoretical explanations[END_REF][START_REF] Arfken | The ultimate glass ceiling revisited: The presence of women on corporate boards[END_REF][START_REF] Maume | Is the glass ceiling a unique form of inequality? Evidence from a random-effects model of managerial attainment[END_REF]] and the "glass escalator", which means that men are accelerated through the organizational ranks [START_REF] Maume | Glass ceilings and glass escalators: Occupational segregation and race and sex differences in managerial promotions[END_REF][START_REF] Williams | The glass escalator: Hidden advantages for men in the "female" professions[END_REF].

Also, the current chapter shows that most of the existing studies on Board-CSR relationship are more likely to explore one-direction of this association, according to which governance features, and therefore CSR committees, help to achieve higher social and financial performances. However, the question of the potential reversal effect of financial performance on governance quality, more specifically on the effectiveness of CSR committees and their compositions, are not yet analyzed. To the best of our knowledge, no studies have examined how financial performance could influence board composition and functioning.

Finally, identifying the timely role of CSR committees in improving CSR strategies should not be taken without consideration of the role of other board committees specifically nomination committees (NC) that are in charge of selecting new board members candidates. NC have definitely influential effects on diversity in (and of) boards and therefore on CSRC composition. To the best of our knowledge, studies on NC role and composition are still scarce. Shedding more light on the cognitive and individual characteristics of committee members is valuable to understand the board dynamics and how they influence firms' strategies (see figure 1.1).

Conclusion

Companies have become more concerned about the protection of human rights, employees' conditions, environmental issues, and communities' expectations. They manage their business according to specific ethical standards. Enhancing governance quality is also among the challenging issues in CSR. The main aim of the current chapter is to put forward the influence of governance features on CSR. It covers these challenging issues.

First, the results of recent empirical studies remain very mixed and the majority of these studies show the existence of a positive association between social performance and financial performance [START_REF] Rost | Reporting biases in empirical management research: the example of win-win corporate social responsibility[END_REF][START_REF] Endrikat | Making sense of conflicting empirical findings: a meta-analytic review of the relationship between corporate environmental and financial performance[END_REF][START_REF] Albertini | Does environmental management improve financial performance? A meta-analytical review[END_REF][START_REF] Dixon-Fowler | Beyond ''does it pay to be green?'' A meta-analysis of moderators of the CEP-CFP relationship[END_REF]Margolis et al., 2009;and Orlitzky and Swanson, 2008]. This could be explained by the difference in terms of CSR strategies adopted by firms.

Second, previous studies show that strategic CSR is a source of original and pioneering actions, where interactions with stakeholders are the key to sustainable performance. Strategic CSR aims to create resources and capabilities that can lead to superior economic performance. While responsive CSR reflects more adaptive behavior. Companies try to gain legitimacy in the eyes of the firm's stakeholders to appear socially responsible [START_REF] Ruggiero | CSR Strategic Approach, Financial Resources and Corporate Social Performance: The Mediating Effect of Innovation[END_REF].

Third, there is an emerging literature on how board diversity could be an advantage for the decision-making process and the key to strategic CSR [START_REF] Bocquet | Strategic CSR for innovation in SMEs: Does diversity matter?[END_REF]. This heterogeneity can promote diversified exchanges and relationships, offer new perspectives, and influence the board's functioning, which in turn can influence its performance [see among others Isidro and Sobral, 2015;and Aggarwal and Dow, 2012]. Specifically, taking into account structural characteristics of boards such as size, duality structure, and board independence, and director's profile such as gender, age, foreign directors and educational level, could be very helpful to better understand how boards of directors influence firm performance from different perspectives [Haniffa and Cooke, 2005;and Gibbins et al., 1990].

Finally, CSR committees have attracted increasing interest [START_REF] Bagh | The Corporate Social Responsibility and Firms' Financial Performance: Evidence from Financial Sector of Pakistan[END_REF][START_REF] Peters | The association between sustainability governance characteristics and the assurance of corporate sustainability reports[END_REF][START_REF] Rodrigue | Is environmental governance substantive or symbolic? An empirical investigation[END_REF]. Specifically, previous studies show that the presence of CSR committees acts as an effective mechanism to enhance CSR performance [START_REF] Bagh | The Corporate Social Responsibility and Firms' Financial Performance: Evidence from Financial Sector of Pakistan[END_REF]. They could help to promote and implement firms' CSR initiatives, which decreases CSR risks and achieve new opportunities [Perters and Romi, 2015;[START_REF] Rodrigue | Is environmental governance substantive or symbolic? An empirical investigation[END_REF].

In future research, it could be interesting to focus on the financial and strategic risk-taking in a responsive or strategic form of CSR.

Biography of the authors

Fig

  Fig. 1.1. Theoretical model

  Author 1: Rania Beji o PhD Student in Finance, Research Assistant at Montpellier Business School o Member of MRM Lab, Université de Montpellier (France) and GEF-2A Lab, Institut Supérieur de Gestion de Tunis, Université de Tunis (Tunisia) Author 2: Ouidad Yousfi o Associate Professor of Finance at IUT Montpellier o Member of MRM Lab, Université de Montpellier (France) Author 3: Abdelwahed Omri o Professor in Financial and Accounting Methods at Institut Supérieur de Gestion de Tunis o Director of GEF-2A Lab, Université de Tunis (Tunisia)

  and 2016. It uses Bloomberg, Factset IODS, and Thomson Reuters for financial and corporate governance data, and VigeoEiris e for CSR scores.

	Table 1.2 Descriptive statistics
	VARIABLE	N	MEAN	STD.	MIN	MAX
	BOARD SIZE INDEPENDENCY	937 937	12.8943 52.5293	3.5268 DEV. 21.4000	3 0	23 100
	DUALITY	937	.33617	.4726	0	1
	GENDER	937	22.1631	13.9675	0	63.6363
	AGE	937	.6247	.1068	0	.7901
	FOREIGN	937	23.5345	21.1733	0	100
	EDUCATIONAL-NATIONALITY BUSINESS-LEVEL EDUCATION MULTIPLE-	937 937 937	69.6529 63.2988 73.30	22.2949 18.4547 16.7990	0 14.2857 9	100 100 100
	DIRECTORSHIPS
	d The SBF120 index consists of the largest 120 capitalizations listed on the French Stock
	Exchange market (SBF: Société des Bourses Françaises).
	e http://vigeo-eiris.com/fr/

f https://www.boardagender.org/files/GMI-Ratings-2012-Women-on-Boards-Survey-F.pdf


Aitor Gonzalez
email: aitor.gonzalez@univ-amu.fr

Vincent Dubut

Emmanuel Corse

Reda Mekdad

Thomas Dechatre

Emese Meglécz
email: emese.meglecz@imbe.fr

Aitor González

VTAM: A robust pipeline for validating metabarcoding data using internal controls

Keywords: metabarcoding, mock sample, negative control, replicates, taxonomic assignation, false posi tives, false negatives

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Metabarcoding has become a powerful approach to study biodiversity from environmental samples (including gut content or faecal samples ). Metabarcoding, however, is prone to some pitfalls, and consequently, every metabarcoding study should be designed in a from-benchtop -to-desktop way ( from sampling to data analysis) to minimi ze the bias of each step on the outcome [START_REF] Alberdi | Scrutinizing key steps for reliabl e metabarcoding of envi ronmental samples[END_REF]Cristescu & Hebert, 2018;[START_REF] Zinger | DNA metab arcoding-Need for robust experimental designs to draw sound ecological conclusions[END_REF] . Several papers have called for good practice in study design, data producti on and analyses to ensure repeatability and comparability bet ween studies. Notably, the importance of mock communit y samples, negative controls, and replicates is fr equently highlighted [START_REF] Alberdi | Scrutinizing key steps for reliabl e metabarcoding of envi ronmental samples[END_REF][START_REF] Bakker | A fungal mock community control for amplicon sequencing experiments[END_REF]Cristescu & Heber t, 2018;[START_REF] O'rourke | A total crapshoot? Evaluating bioinf ormatic decisions in animal diet metabarcoding analyses[END_REF] . However , their use in bioinformatics pipelines is often limited to the verification of expectations.

In this study, we present the bioinformatics pipeline, VTAM (Vali dation and Taxonomic Assignation of Metabarcoding data) that effectively integrates negative controls, mock communities and technical replicates to control experimental fluctuations (e.g. sequencing depth, PCR stochastic ity) and validate metabarcoding data.

A recent study on the effect of different steps of data curation on spatial partitioning of biodiversity listed the following potential problems: Sequencing and PCR errors, presence of highly spurious sequences, chimeras, internal or external contamination and dysfunctional PCRs (Calderón-Sanou, Münkemüller, Boyer, Zinger, & Thuiller, 2020) . They showed that exhaustive curation and ensuring repeatability by technical replicates are necessary , especially for biodiversity measurements. Ideally, a metabarcoding wor kflow should address all of these technical errors. Exist ing tools , however, ar e either highly flexible but too complex or they do not include the curation of all pot ential biases (Mahé, Rognes, Quince, de Vargas, & Dunthor n, 2014;[START_REF] Boyer | obitools: a unix -inspired software package f or DNA metabarcoding[END_REF]Callahan et al., 2016;[START_REF] Edgar | UNOISE2: improved error -correction for Illumina 16S and ITS amplicon sequenci ng[END_REF][START_REF] Rognes | VSEARCH: a versatile open source t ool for metagenomics[END_REF][START_REF] Bolyen | Reproducible, interactive, scalable and extensible microbiome data science using QIIME 2[END_REF] . The filtering st eps of VTAM aim to address these point s and include several additional features that are unique or rarely found in existing pipelines: (i) the use of internal controls and (ii) replicates to optimize filtering parameter values ; (iii) the integration of multiple overlapping markers and (iv) filtration to address crosssample contamination , including tag-jumps. Finally, VTAM is a variant -based filtering pipeline (such as other denoising methods: Callah an et al., 2016;[START_REF] Edgar | UNOISE2: improved error -correction for Illumina 16S and ITS amplicon sequenci ng[END_REF] that deals with amplicon sequence variants (ASVs) .

Features 2.1 Implementation

VTAM is based on the method described in [START_REF] Corse | A from -benchtop -to-desktop workflow for validating HTS data and for taxonomic identification in diet metabarcoding studies[END_REF]. It is a command-line application that runs on Linux, MacOS or Wi ndows Subsystem for Linux (WSL).

VTAM is implemented in Python 3, using a Conda environment to ensure repeatability and easy installation of VTAM and these third -party applications: WopMars (https://wopmars.readthedocs.io ), NCBI BLAST, Vsearch [START_REF] Rognes | VSEARCH: a versatile open source t ool for metagenomics[END_REF], Cutadapt [START_REF] Martin | Cutadapt removes adapter sequences from high -throughput sequencing reads[END_REF] . Data is stor ed in an SQLite database that ensures traceability. 4

Workflow

Table 1 summarizes the different commands and steps of VTAM, their purpose and the related error type s.

Pre-processing ( optional)

An example of the dat a structure is illustrated in Fig. 1.

Paired-end FASTQ files are merged, reads are trimmed and d emultiplexed according to forward and reverse tag combination s.

Filtering

Demultiplexed reads are dereplicated and ASVs are stored in a n SQLite database.

All occurrences are characteri zed by their read count.

FilterLFN: eliminates occurrences likely due to Low Frequency Noise . Occurrences are filtered out if they have low read counts (i) in absolute terms (N i j k is small, where Nijk is the read count of variant i in sample j and replicate k), (ii) compared to the total number of reads of the sample -replicate (Nijk/Njk) or (iii) compared to the total number of reads of the variant ( N i j k /Ni).

FilterMinReplicateNumber : Occurrences are retained only if the ASV is pre sent in at least a user -defined number of replicates.

FilterPCRerror: ASVs with one difference from another ASV of the same sample are filtered out if the proportion of their read counts is below a user-defined threshold value .

FilterChimera runs the uchime3_denovo chi mera filtering implemented in vsearch.

FilterRenkonen removes whole replicates that are too different compared to other replicates in the same sample.

FilterIndel and FilterCodonStop are intended to detect pseudogenes and should only be used for coding markers. FilterIndel eliminates all variants, with aberrant length, where the modulo three of the length is different from the majority .

FilterCodonStop eliminates all variants that have codon STOP in all reading frames of the direct strand.

The output of the filters is an AS V table wit h validated variants in lines, sample s in columns and the sum of read counts over replicates in the cells.

Taxonomic assignation

Taxonomic assignation is based on the Lowest Taxonomic Group method described in detail in Supporting Information 1. The taxonomic reference dat abase has a BLAST format with taxonomic identifiers so that custom database s or the complete NCBI nucleotide database can be used by VTAM. A custom taxonomic reference database of COI sequences mined from NCBI nucleotide and BOLD (https://www.boldsystems.org/ ) databases i s available with the pr ogram.

Parameter optimization

Users should first identify expected and unexpected occurrences based on the first filtration with default parameters . The optimization step will guide users to choose parameter values that maximize the number of expected occurrences in the dataset and minimize the number of unexpected occurrences (false positives) . Parameters are optimized for the three LFN filter s and t he FilterPCRerror. Optimized parameters can then be used to repeat the filtering steps.

Pool runs/markers

A run is FASTQ data f rom a sequencing run and a marker is a regi on of a locus amplified by a primer pair. The pool command produces an ASV table with any number of run -marker combinations. When m ore than one overlappi ng marker is used, ASVs identical to their overlapping parts are pooled to the same li ne.

Benchmarking

VTAM was tested wit h two published metabarcoding datasets: a fi sh dataset obtained from fish faecal samples [START_REF] Corse | A from -benchtop -to-desktop workflow for validating HTS data and for taxonomic identification in diet metabarcoding studies[END_REF] , and a bat dataset obtained from bat guano samples [START_REF] Galan | Metabarcoding for the parallel identification of several hundred predators and their prey: Application to bat species diet analysis[END_REF] . Both datasets included negative controls, mock samples and three PCR replicates. A fragment of the COI gene was amplified using two overlapping markers in the fish dataset, and one in the bat dataset (See details in the original studies).

Both datasets were analysed by VTAM . The fish dataset was analysed separately for the two markers and the results of both markers were pooled together.

Both datasets were also analysed with the DADA2 denoising algor ithm (Callahan et al., 2016), one of the most widely used methods for metabarcoding data curation.

The output of DADA2 was filtered by LULU [START_REF] Frøslev | Algorithm for post -clustering curation of DNA amplicon data yields reliable biodiversity estimates[END_REF] t o further eliminate probable false positive occurrences. Then the three repli cates of each sample were pooled (as in VTAM), only accepting the occurrence if it was present in at least two replicat es (Supporting inform ation 2).

We compared the α-di versity and β -diversity obtained for the environmental samples to address the effect of the curation pipelines on diversity estimations. αdiversity was estimated using both ASV richness and cluster richness ( clusters aggregate ASVs with <3% divergence) , and β-diversity was summarized using the Bray-Curtis pairwise dissimilarit y index. (Supporting information 3).

In the fish dataset , all expected variants in the mock samples were validated by both pipelines. However, in the bat dataset, t wo expected variants had very low read abundance (2-18 reads/replicate ), which were in the range of the number of reads in the negative controls (ten out of the 19 negative controls had at least one read count greater than 18 ). Therefore, we i gnore d these two expected variants in the Bulk France mock sample, and we optimized the VTAM parameters to retain all other expected occurrences.

After filtering with VTAM, the number of f alse positives in the mock samples was markedly lower than with DADA2 (Table 2). Similarly, ASV and cl uster richness were on average two times lower with VTAM than with DADA2 in environmental samples (Fig. 2A andB). In contrast, dissimilarities between samples were higher with VTAM (Fig. 2D) . In both pipelines , most clusters contained a single ASV (Supporting information 3; Fig. 2C).

Discussion

Metabarcoding is known to be prone to two types of error s: false negatives and false positives . Based on controls (negative and mock samples), VTAM aims to find a compromise between these two error types by minimizing false positive occurrences while retaining expected variant s in mock samples to avoid false negatives. Therefore, the mock samples should contain both well and weakly amplified taxa, where the abundance , i.e. the number of reads , of weakly amplified taxa is marginally higher than those found i n negative samples. This should ensure finding filtering parameter values that simultaneously minimize false positives and false negatives. Additionally, in large-scale studies with more than one sequencing run, the use of identical mock samples in all runs can ensure comparability among runs if they consistent ly yield the same resul ts .

The use of technical replicates is another important tool to limit false positive s and false negatives (Alber di et al. 2018[START_REF] Corse | A from -benchtop -to-desktop workflow for validating HTS data and for taxonomic identification in diet metabarcoding studies[END_REF]. False posit ives can be strongly reduced by only accepting variants in a sample if they are present in at least a certain number of replicates. This strategy is strongly advised to reduce experimental stochasticity and vali date ASV occurrences. Furtherm ore, removing replicates with radically different compositions (Renkonen filter) further reduces the effect of experimental stochasticity [START_REF] De Barba | DNA metabarcoding multiplexing and validation of data accuracy for diet assessment: application to omnivorous diet[END_REF] . Additionally, false negatives can be further reduced by amplifyi ng several markers [START_REF] Corse | One -l ocus-several -primers: A strategy to improve the taxonomic and haplotypic cover age in diet metabarcoding studies[END_REF]. If the different markers overlap , VTAM can pool sequences that are identical in their overlapping regions . This i ntegrates the results of different markers unambiguously.

While false positive occurrences du e to sequencing and PCR error s are generally well detected by denoi sing pipelines such as DADA2, tag -jump and cross-sample contamination are rarely taken into account (but see [START_REF] Boyer | obitools: a unix -inspired software package f or DNA metabarcoding[END_REF]Edgar, 2016a). However, failing to filter out these artefacts is likely to inflate false positive occurrences and artificially increase inter-sample similarities. In fact, t he DADA2 based pipeline produced ASV and cluster richness per sample that was on average twice as high as with VTAM and even higher for some samples (Fig. 2 A,B). On the other hand, dissimilarities between samples were lower after DADA2 filtration. Additionally, the near 1:1 correlation between ASV and cluster richness in both pipelines indicated that most clusters contained just one ASV per sample.

This supports the notion that diversity inflation in DADA2 resulted from unfiltered tag-jump contamination s rather than PCR or sequencing errors as t his would have produced more ASVs that belong to the same cluster. Our VTAM pi peline , therefore, appears mor e appropriat e for comparing the diversity bet ween samples and for investigating t he biological response s to environmental change .

Conclusions

The VTAM metabarcoding pipeline aim s to address known technical errors during data analysis (Table 1) to validate metabarcoding data . It is a complete pipeline from raw FASTQ data to curated ASV table s with taxonomic assign ments.

The implementation of VTAM provides several advantages such as using a Conda environment to facilitate the installation, data storage in SQLite database for traceability and the possibility to run one or several sequencing run -marker combinations using the same command. VTAM includes features rarely considered in most metabarcoding pipelines, and w e beli eve it provides a useful tool for the analysis and validation of metabarcoding data for conducting robust analyses of biodiversity.

development. EM, AG , VD and EC wrote the manuscript. All authors contributed critically to the draft and approved the final version of the manuscr ipt.

Figures and tables

F

  i g u r e 1 . A n e x a m p l e o f a d a t a s t r u c t u r e w i t h o n e r u n , t w o m a r k e r s a n d t h r e e r e p l i c a t e s f o r e a c h s a m p l e . S 1 -R 1 : R e p l i c a t e 1 o f S a m p l e 1. R e p l i c a t e s a r e n o t e s s e n t i a l b u t s t r o n g l y r e c o m m e n d e d . S a m p l e s s h o u l d i n c l u d e a t l e a s t o n e m o c k s a m p l e a n d o n e n e g a t i v e c o n t r o l .

F

  i g u r e 2 . D i v e r s i t y e s t i m a t e s f r o m t h e f i s h a n d b a t d a t a s e t s , b a s e d o n t h e V T A M a n d D A D A 2 -b a s e d p i p e l i n e s . A) A S V r i c h n e s s p e r s a m p l e B ) c l u s t e r r i c h n e s s p e r s a m p l e C ) T h e c o r r e l a t i o n b e t w e e n A S V a n d c l u s t e r r i c h n e s s . Pv a l u e i n d i c a t e s a s i g n i f i c a n t s l o p e d i f f e r e n c e b e t w e e n t h e t w o p i p e l i n e s . D ) β -d i v e r s i t y w as e s t i m a t e d u s i n g t h e B r a y -C u r t i s d i s s i m i l a r i t y i n d e x c a l c u l a t e d f o r e a c h p a i r w i s e s a m p l e c o m p a r i s o n . S o l i d l i n e s i n d i c a t e l i n e a r r e g r e s s i o n l i n e s , h a t c h e d l i n e s a r e t h e 1 : 1 r e f e r e n c e l i n e s . T a b l e 1 . L i s t o f V T A M c o m m a n d s a n d t h e i r r o l e s .

T a b l e 2 .

 2 N u m b e r o f f a l s e p o s i t i v e o c c u r r e n c e s c o m p a r e d t o t h e t o t a l n u m b e r o f o c c u r r e n c e s . I n n e g a t i v e c o n t r o l a n d m o c k s a m p l e s , t h e c o u n t o f f a l s e p o s i t i v e s i s p r e c i s e , s i n c e t h e s a m p l e c o m p o s i t i o n i s k n o w n .

Acknowledgements

We thank Diane Zarzoso -Lacoste and Samanta Ortuno Miguel for valuable comments on the use of VTAM , Luc Giffon and Lionel Spinelli for the development of Wopmars and Kurt Villsen for English editing. Centre de Calcul Intensif d' Aix -Marseille is acknowledged for granting access to its high performance computing resources. This work i s a contribution to the European project SEAMoBB, f u nded by ERA-Net Mar -TERA and managed by ANR (number ANR_17_MART -0001_01).

Data Availability

VTAM is available at https://github.com/aitgon/vtam . A detailed user manual is found at https://vtam.readthedocs.io .

Empirical data used in this paper are available from the Dryad Digital Repository https://datadryad.org/stash/dataset/doi:10.5061/dryad.f40v5 and https://datadryad.org/stash/dataset/doi:10.5061/dryad.kv02g .

Authors' contributions