Camille Bernery
email: camille.bernery@universite-paris-saclay.fr

Céline Bellard

Franck Courchamp

Sébastien Brosse

Boris Leroy

Important characteristics determining the success of non-native freshwater fish introduction, establishment, and impact

Keywords: aquaculture, ecology, exotic, freshwater fish, introduction pathways, invasion steps, morphology, ornamental trade, socioeconomic, traits

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Introduction

The rise of global trade has led to an increase in the introductions of invasive alien species worldwide (Seebens et al., 2017). Nowadays, biological invasions are recognized as a major threat to biodiversity, as they are the second cause of species extinction worldwide [START_REF] Bellard | Global patterns in threats to vertebrates by biological invasions[END_REF]. Freshwater fish are among the most introduced taxa, and non-native freshwater fish are now established in all biogeographical realms [START_REF] Gozlan | Introduction of non-native freshwater fish : Is it all bad?[END_REF][START_REF] Leprieur | Fish Invasions in the World's River Systems : When Natural Processes Are Blurred by Human Activities[END_REF].

Established non-native freshwater fish species have diverse impacts, ranging from local hybridization with native faunasuch as between the invasive rainbow trout (Oncorhynchus mykiss) and native westslope cutthroat trout (Oncorhynchus clarkii lewisi) in Canadian rivers as reported by [START_REF] Muhlfeld | Hybridization rapidly reduces fitness of a native trout in the wild[END_REF] to profound changes in species assemblages, leading to taxonomic homogenization across large regions such as the Laurentian Great Lakes [START_REF] Campbell | Functional differentiation accompanies taxonomic homogenization in freshwater fish communities[END_REF].

Nonetheless, not all introduced non-native fish species become established or have impacts.

Previous studies have shown that the success of each step of the invasion is influenced by three categories of drivers: species characteristics, ecological characteristics of the native or recipient ecosystems, and socioeconomic characteristics. Regarding species characteristics, non-native fish species with a broad food spectrum are more establish more easily than more specialized species [START_REF] Ruesink | Global Analysis of Factors Affecting the Outcome of Freshwater Fish Introductions : Outcome of Fish Introductions[END_REF]. Likewise, for ecological characteristics, the size of the native range influences the establishment and spread of non-native species (Marchetti et al., 2004a).

Concerning socioeconomic characteristics, some introduction pathways are known to be an important source of freshwater fish introductions and establishments such as aquaculture and ornamental trade [START_REF] Gozlan | Current knowledge on nonnative freshwater fish introductions[END_REF]. Socioeconomic characteristics can also relate to the human use of fish, as the development of the ornamental trade has caused a recent rise in fish introductions [START_REF] Magalhães | Invasion risks posed by ornamental freshwater fish trade to southeastern Brazilian rivers[END_REF]. Moreover, we can expect a strong interaction between species characteristics and socioeconomic drivers. For instance, species introduced through the aquaculture trade are more likely to be large species [START_REF] Su | Morphological sorting of introduced freshwater fish species within and between donor realms[END_REF], while those introduced through ballast waters are more likely to be small species [START_REF] Wonham | Fish and ships : Relating dispersal frequency to success in biological invasions[END_REF].

Understanding the different characteristics that promote invasions is extremely important in order to improve predictions about future invasions [START_REF] Planquette | MAcroecological Framework for Invasive Aliens (MAFIA) : Disentangling large-scale context dependence in biological invasions[END_REF].

Several papers have focused on understanding the characteristics of successful invasive freshwater fish species using quantitative analysis (e.g., [START_REF] García-Berthou | The characteristics of invasive fishes : What has been learned so far[END_REF][START_REF] Snyder | Updated invasion risk assessment for Ponto-Caspian fishes to the Great Lakes[END_REF][START_REF] Su | Morphological sorting of introduced freshwater fish species within and between donor realms[END_REF]. However, species, ecological, and socioeconomic characteristics have rarely been studied together at the global scale for freshwater fish (but see [START_REF] Ruesink | Global Analysis of Factors Affecting the Outcome of Freshwater Fish Introductions : Outcome of Fish Introductions[END_REF][START_REF] Planquette | MAcroecological Framework for Invasive Aliens (MAFIA) : Disentangling large-scale context dependence in biological invasions[END_REF]. Indeed, most studies are conducted at a local scale with the analyses performed on a limited number of species [START_REF] Marchetti | Invasive species profiling? Exploring the characteristics of non-native fishes across invasion stages in California[END_REF][START_REF] Ribeiro | Life-history traits of non-native fishes in Iberian watersheds across several invasion stages : A first approach[END_REF], often without considering the different types of drivers [START_REF] Ribeiro | Life-history traits of non-native fishes in Iberian watersheds across several invasion stages : A first approach[END_REF] or the steps of the invasion process (e.g., [START_REF] García-Berthou | The characteristics of invasive fishes : What has been learned so far[END_REF][START_REF] Ruesink | Global Analysis of Factors Affecting the Outcome of Freshwater Fish Introductions : Outcome of Fish Introductions[END_REF][START_REF] Lawson | Life history strategies differentiate established from failed non-native freshwater fish in peninsular Florida[END_REF]. As a result, there is currently no consensus about the drivers influencing the invasion success of freshwater fish globally (but see [START_REF] García-Berthou | The characteristics of invasive fishes : What has been learned so far[END_REF].

To fill this gap, we aimed to determine the drivers of the different steps of invasions (i.e., introduction, establishment, and impact) of freshwater fish species at the global scale using a statistical modeling approach. For 307 freshwater fish species, we considered their species (functional and morphological traits), ecological (features of the native ecosystems of the species), and socioeconomic characteristics (introduction pathways and human use). We investigated the link between these characteristics and the invasion patterns measured as the number of countries where each species is introduced, established, and reported to impact the native fauna or recipient ecosystem. We built our models based on initial assumptions for each invasion step. First, we hypothesized that the species characteristics influencing the introduction success are dependent on the introduction pathway (e.g., given that large-bodied fishes are more interesting for anglers, they have a greater chance of being introduced through the "angling" pathway; [START_REF] Peoples | Fishing pressure and species traits affect stream fish invasions both directly and indirectly[END_REF], which is itself influenced by the native region of non-native species (e.g., species from the ornamental trade tend to be native in tropical countries, [START_REF] Gertzen | Quantifying invasion pathways : Fish introductions from the aquarium trade[END_REF]. As the establishment step depends on the adequacy between the recipient ecosystem and the needs of the species, we hypothesize the higher success of generalist species (i.e., broad diet) and species introduced in large numbers (i.e., with high propagule pressure). High parental care has also been highlighted in several studies as an important characteristic influencing establishment [START_REF] Marchetti | Invasive species profiling? Exploring the characteristics of non-native fishes across invasion stages in California[END_REF][START_REF] Lawson | Life history strategies differentiate established from failed non-native freshwater fish in peninsular Florida[END_REF]. Few studies have focused on the impact step. However, it has already been demonstrated that species at the top trophic levels have a large impact, notably because prey in the new environment are naive to the new predator [START_REF] Moyle | Biological invasions of fresh water : Empirical rules and assembly theory[END_REF][START_REF] Howeth | Predicting invasiveness of species in trade : Climate match, trophic guild and fecundity influence establishment and impact of non-native freshwater fishes[END_REF]. We can hypothesize that species with a nekton diet will have a greater impact than species at low trophic levels.

Material and methods

Species-level variables influencing the invasion success of freshwater fish

To understand the drivers of success in exotic freshwater fish introduction, establishment, and impact, we compiled species-level variables pertaining to their species, ecological, and socioeconomic characteristics. We chose these variables because they are assumed to influence species invasions (see Table 1 for justifications and hypotheses; [START_REF] Planquette | MAcroecological Framework for Invasive Aliens (MAFIA) : Disentangling large-scale context dependence in biological invasions[END_REF]. We obtained 20 species-level variables from five data sources: (i) FishBase (Froese and Pauly, 2019, version 19.04, accessed with the "rfishbase" R package; Boettiger et al., 2012), which includes data on the invasive status, characteristics, and human use of 34,300 fish species at the global scale; (ii) the FISHMORPH morphological database [START_REF] Brosse | FISHMORPH : A global database on morphological traits of freshwater fishes[END_REF], which includes information on the morphological traits of 9,150 fish species; (iii) the database on freshwater fish occurrences complied by [START_REF] Tedesco | A global database on freshwater fish species occurrence in drainage basins[END_REF], which has distribution data for 14,953 freshwater fish species in 3,119 basins worldwide; (iv) the global biogeographical regions of freshwater fish [START_REF] Leroy | Global biogeographical regions of freshwater fish species[END_REF]; and (v) the world climate database WorldClim [START_REF] Fick | WorldClim 2 : New 1-km spatial resolution climate surfaces for global land areas[END_REF]. We summarized all variables in Table 1 and describe them in detail hereafter.

Species characteristics

We defined freshwater fish as all species with a freshwater habitat listed as one of their preferred habitats in the table species() of the "rfishbase" R package.

Main diet and number of diets -To retrieve data on species diets, we used the "FoodI" column of the fooditems() table of the "rfishbase" R package. We used two variables: (i) the most represented diet for each species as the main diet and (ii) the total number of diets (Table 1). In the rare cases (37 out of 307 species considered here) where several diets were equally represented, we chose the most represented diet within the order. We made an exception for Megalops atlanticus to which we had associated the "nekton" main diet, because this species, which is a known predator of crabs and small fish [START_REF] Planquette | MAcroecological Framework for Invasive Aliens (MAFIA) : Disentangling large-scale context dependence in biological invasions[END_REF], has two main diets that are also the two most represented diets of the order.

Swimming ability -To analyze the influence of swimming ability on invasion success, we used two variables from [START_REF] Su | Morphological diversity of freshwater fishes differs between realms, but morphologically extreme species are widespread[END_REF]. First, we used the pectoral fin vertical position (i.e., ratio of pectoral fin position relative to body depth), which reflects the swimming style (Table 1).

Lateral pectoral fins are used for propulsion and fine movements, whereas ventral pectoral fins often characterize fish with less precise movements [START_REF] Blake | Fish functional design and swimming performance[END_REF][START_REF] Su | Morphological diversity of freshwater fishes differs between realms, but morphologically extreme species are widespread[END_REF]. Second, we used the ratio of body length to body depth, which reflects fish hydrodynamics [START_REF] Villéger | Functional ecology of fish : Current approaches and future challenges[END_REF][START_REF] Su | Morphological diversity of freshwater fishes differs between realms, but morphologically extreme species are widespread[END_REF] (Table 1).

Parental care -We used the parental care variable from the "RepGuild1" column of the species() table of the "rfishbase" R package (Table 1).

Total length (TL) -To gather this information, we used the "TL" column of the morphometrics() table of the "rfishbase" R package. As a species can have several different total length, we took the median of all the given total length for each species.

Species taxonomy -We used FishBase as the taxonomic reference (Froese and Pauly, 2019).

For each species, we completed the order using the load_taxa() table from the "rfishbase" R package. The number of species per order was heterogeneous, which can cause statistical issues due to class imbalances, especially for minority classes (i.e., orders with only one or a few species). Therefore, we kept the main orders (i.e., Characiformes, Cypriniformes, Cyprinodontiformes, Perciformes, and Siluriformes) in the models and grouped together the remaining orders in the "other" category.

Ecological characteristics

Main native bioregion -Freshwater fish have evolved in isolated biogeographical regions for the past 10-20 million years [START_REF] Leroy | Global biogeographical regions of freshwater fish species[END_REF]. Consequently, each bioregion has distinct characteristics pertaining to its environmental conditions, faunistic composition, and associated interactions. In addition, biogeographical regions broadly cover the main geopolitical regions of the world, with distinct intra-region and inter-region properties in terms of species displacement and propagule pressure. Hence, the region of origin of a species is a proxy of several characteristics: environmental conditions, diversity of interactions during evolutionary history, and chances of introduction to non-native ecosystems (Table 1). We defined two variables based on the biogeographical regions of [START_REF] Leroy | Global biogeographical regions of freshwater fish species[END_REF]: the number of native bioregions (defined as bioregions where the species has native occurrences) and the main bioregion, defined as the bioregion with the highest number of native basins where the species is found. It is important to note that 85% of the species considered here have only one bioregion.

We excluded species that did not occur within the limits of the bioregions. A total of 2 species equally occurred in two native bioregions. For these species, we selected one region at random and verified whether this choice had an impact on the model results using sensitivity analysis.

Temperature amplitude, minimum and maximum temperature in the native basins -We used the minimum temperature of the coldest month and the maximum temperature of the warmest month from Worldclim [START_REF] Fick | WorldClim 2 : New 1-km spatial resolution climate surfaces for global land areas[END_REF] to derive two variables: annual maximum temperature and temperature amplitude (Table 1). We excluded the annual minimum temperature, as this variable was correlated to temperature amplitude. We only took into account the 0.95 quantile of the maximum temperature of the warmest month and the 0.05 quantile of the minimum temperature of the coldest month across the native basins for each species to avoid extreme outlier values.

Socioeconomic drivers

Introduction pathways -Using the introduction() table from the "rfishbase" R package, we considered each pathway as an independent variable (Table 1). Therefore, species could have several introduction pathways. We filtered out pathways containing only a few species. We thus reclassified pathways documented in FishBase into the seven following categories: aquaculture, sport/angling, species control, diffusion, accidental, fisheries, and ornamental trade (Appendix 1).

Use by humans -Four columns of the species() table in the "rfishbase" R package indicate the human use of species through fisheries ("Importance" column), bait ("Usedasbait" column), sport ("GameFish" column), or aquariums ("Aquarium" column). If a species is used in at least one of these four sectors (i.e., belonging to a category other than "never/rarely," "of no interest," "of potential interest," or "potential"), we considered this species to be used by humans.

 Detritus  Nekton  Plants  Zoobenthos  Zooplankton
Broad food spectrum, piscivorous diet, as well as some specialized diets facilitate establishment [START_REF] Ruesink | Global Analysis of Factors Affecting the Outcome of Freshwater Fish Introductions : Outcome of Fish Introductions[END_REF]Tonella et al., 2018). A nekton diet can be associated with species having an impact [START_REF] Moyle | Biological invasions of fresh water : Empirical rules and assembly theory[END_REF][START_REF] Howeth | Predicting invasiveness of species in trade : Climate match, trophic guild and fecundity influence establishment and impact of non-native freshwater fishes[END_REF]. [START_REF] Marchetti | Invasive species profiling? Exploring the characteristics of non-native fishes across invasion stages in California[END_REF][START_REF] Lawson | Life history strategies differentiate established from failed non-native freshwater fish in peninsular Florida[END_REF].

Number of diets

Total length Quantitative variable

At the introduction step, the body length of successful species is linked to the introduction pathway [START_REF] Wonham | Fish and ships : Relating dispersal frequency to success in biological invasions[END_REF][START_REF] Su | Morphological sorting of introduced freshwater fish species within and between donor realms[END_REF]. At the establishment step, body length depends on the environmental conditions [START_REF] Vila-Gispert | Life-history traits of invasive fish in small Mediterranean streams[END_REF]. At the impact step, small species can have greater impacts [START_REF] Marchetti | Alien fishes in California watersheds : Characteristics of successful and failed invaders[END_REF].

Taxonomy  Cypriniformes  Cyprinodontiformes  Siluriformes  Characiformes  Other
Order is a surrogate for missing characteristics that could influence species success at different stages of the invasion.

Ecological characteristics

Temperature amplitude in the native basins

Quantitative variable

Temperature amplitude in native basins can be a proxy of temperature tolerance. Temperature tolerance influences the establishment and spread of invasive species (Kolar and Lodge, 2002;[START_REF] Marchetti | Invasive species profiling? Exploring the characteristics of non-native fishes across invasion stages in California[END_REF][START_REF] Snyder | Updated invasion risk assessment for Ponto-Caspian fishes to the Great Lakes[END_REF].

Maximum temperature in the native basins

Quantitative variable

Main native bioregion

 Nearctic  Palearctic  Sino-Oriental  Neotropical  Ethiopian  Madagascan
Native bioregions reflect socioeconomic characteristics, propagule pressure, and environmental conditions.

Response variables

In this study, we considered three steps of the invasion: introduction, establishment, and impact.

We gathered data on three variables that reflect these three steps: the number of countries where species are introduced, the number of countries where introduced species are established, and finally, the number of countries where the established species have impacts. To obtain information about these variables for each species, we used the introductions() function of the "rfishbase" R package. This table describes the introduction events of fish species, giving the location of the introduction, the species concerned, as well as the establishment and impact status of the species.

Number of countries where species are introduced, established, and have impacts

We used the locations found in the "TO" column of the introduction() table of the "rfishbase" R package. It should be noted that some species were simply transported to the new location without being introduced to the wild. These species were impossible to separate from others, although they remain scarce because most alive imported species are introduced (intentionally or accidentally) to the natural environment [START_REF] Ju | Emerging risks of non-native species escapes from aquaculture : Call for policy improvements in China and other developing countries[END_REF][START_REF] Magalhães | All the colors of the world : Biotic homogenization-differentiation dynamics of freshwater fish communities on demand of the Brazilian aquarium trade[END_REF]. Thus, we assumed that all species were introduced to the wild. The locations listed in FishBase were not standardized at a specific spatial scale (names ranged from the names of cities to entire continents), so we manually harmonized names to the country scale. We excluded all records above the country scale. We grouped islands located far from their country by archipelago or considered them separately when they did not belong to an archipelago. As some of the introductions were old, the listed countries no longer exist and could not be grouped or assimilated with the new country. This was the case for the USSR and Korea. We therefore considered these countries independently. When the spatial grain was the river or lake, we considered all the riparian countries independently. We listed as "Unknown" any locations given at a larger scale than a country (e.g., "Europe") or locations that could not be identified.

The list of 208 countries considered in this study is available in Appendix 2.

For each species, we counted the number of countries where the species were introduced, established, or had impacts. Concerning the establishment step, all the species noted as "Yes," "Probably Yes," "Established," or "Probably established" in the "Estabwild" column of the introduction() table were taken as species established in the wild in the considered locations.

We removed from the analysis the species that were listed as established but not introduced beforehand, as we could not access the establishment location of these so-called non-introduced species. We took as established any species that had an impact but were not established (i.e., "No" or "Probably no" in the "Estabwild" column) or had an unknown establishment status.

Concerning the impact step, we considered that all the species noted as "Yes," "Probably some," or "Some" in the "EcolEff" column of the introduction() table had ecological impacts in the considered locations.

We obtained 840 species with an introduced status (307 introduced species, 533 non-introduced species). For the 307 introduced species, the number of countries where the species were introduced was provided. Among these 307 introduced species, 217 species were established in at least one country and 117 had ecological impacts in at least one country.

Statistical analysis

To determine the characteristics of the species at each step of the invasion process, we used generalized linear models (GLM) to analyze the influence of species, ecological, and socioeconomic characteristics on the number of countries where the species are introduced, established, or have impacts. First, we assessed the correlations between all the 20 explanatory variables. We used the ggcorr() R function of the GGally package [START_REF] Schloerke | No saturation in the accumulation of alien species worldwide[END_REF] to explore the Spearman correlations between quantitative variables. We also used the model.matrix() from the stats package (R Core Team, 2020) to separate each modality of the numerical variables into binary variables. We then used the cor() function (stats package; R Core Team, 2020) to explore the Pearson correlations between the new binary variables and between the binary and quantitative variables. To avoid multicollinearity, we centered the variables "total length," "temperature amplitude in the native region," and "number of diets."

We performed GLMs considering all the species, regardless of their introduction pathway, to explain the number of countries where the species (i) were introduced, (ii) were established, and (iii) had impacts (Appendix 3). We used the 20 explanatory variables and six interactions between the variables: the interactions between total length and temperature amplitude, between total length and order, between total length and ornamental pathway, between total length and sport/angling pathway, between total length and aquaculture pathway, and between number of diets and order (Appendix 3). We also conducted the same analyses while considering only the species introduced through the aquaculture pathway or through the ornamental trade pathway (i.e., 11 variables and 3 interactions; see Appendix 3).

As our data were count data, we computed these GLMs with Poisson distributions or negative binomial distributions when our response variables were overdispersed. To check for overdispersion, we used the dispersiontest() function from the "AER" R package (Kleiber and Zeileis, 2008). Then we used the stepAIC() function from the "MASS" R package [START_REF] Venables | Modern Applied Statistics with S, Fourth edition[END_REF] and a stepwise selection to choose the best model based on the Akaike information criterion. For each model, a pseudo-r2 was estimated using the following formula:

1 -Model Deviance / Model Null Deviance. We identified the significant variables of each model using the Anova() function from the "car" R package [START_REF] Fox | An R Companion to Applied Regression[END_REF]. The variable importance of each variable in the models (i.e., absolute value of the t-statistic of each model variable) was calculated using the varImp() function from the "caret" R package [START_REF] Kuhn | Building Predictive Models in R Using the caret Package[END_REF].

To take into account the potential fluctuations due to the randomly chosen main diet and main regions for some species, we performed sensitivity analysis. For the species with several main diets or several main native regions, we randomly selected the main diet and the main native region. Then we performed the above GLMs on the new dataset. We repeated the process 100 times to observe the variation in the results due to the random choices. The results of these analyses are presented in Appendix 4.

Results

All species

Considering the 307 introduced species, species introduced in a high number of countries were associated with a high number of different introduction pathways (variable importance [VI] = 10), a high level of parental care (VI = 5.3 for the linear relation), had aquaculture (VI = 4.5)

or fisheries (VI = 2.7) as one of their introduction pathways, and had a high number of diets (VI = 2.4) (Fig. 1a., Fig. 4). Siluriformes with a high number of diets also tend to be introduced in many countries (VI = 2.3). The establishment step model showed similar results to the introduction model for selected variables (Fig. 1b., Fig. 4), except that the species established in a high number of countries were not significantly more introduced through the aquaculture pathway. Finally, species with impacts in a high number of countries were associated with most of the pathways (except for species control, accidental, and aquaculture), a high level of parental care, and a high number of diets when species were from the Siluriformes order (Fig. 1c., Fig. 4). Nonetheless, parental care was only significant in 22% of models in sensitivity analysis, thus reducing its robustness (Appendix 4C).

Species introduced through the aquaculture pathway

Species introduced through aquaculture (Fig. 2a.) in a high number of countries were associated with a high number of diets (VI = 2.9) and more often belonged to the Cypriniformes order (VI = 1.6). They were also more often associated with high parental care (significant variable in 57% of models in sensitivity analysis) (Fig. 2a., Appendix 4A). In terms of establishment, species established in many countries by aquaculture had a high number of diets (VI = 3.8) and belonged to all orders except for Characiformes, even though this tendency was less robust for the Cyprinodontiformes order (Appendix 4). They were also often associated with high parental care (significant variable in 76% of models; Fig. 3b., Appendix 4B).

Species introduced through the ornamental trade pathway

We analyzed the characteristics of 126 species introduced through ornamental trade (Fig. 3a.).

Species introduced to many countries were not hydrodynamic (VI = 5.5), were native to the Neotropical (VI = 2.5) or Sino-Oriental regions (VI = 2.3), and had a high number of diets (VI = 1.6).

Concerning the establishment step (Fig. 3b.), we considered a subset of 70 established species among those introduced through the ornamental trade pathway. Species established in many countries were not hydrodynamic (VI = 4.9), were from the Cyprinodontiformes (VI = 4.3) or Cypriniformes (VI = 2.4) orders, and mainly came from the Ethiopian (VI = 1.2) or Neotropical (VI = 1.1) regions.

Discussion

Using the socioeconomic, ecological, and species characteristics of 307 freshwater fish species, we were able to identify a profile of successful invasions for each step of the invasion process (Figure 4, Appendix 5). As we hypothesized, we found that species characterized by a broad diet and high parental care as well as multiple socioeconomic pathways of introductions, including fisheries and aquaculture, were particularly successful at being introduced and established in multiple countries. By contrast, socioeconomic characteristics seem highly important to explain the impact of freshwater fish in many countries, and contrary to our hypothesis, diet did not have a significant effect on the success of this step.

Introduction step

We found that species introduced to many countries have specific characteristics. As hypothesized, multiple introduction pathways favored widespread introductions, with different entry routes increasing the chances of being transported and introduced in many locations. For example, the common carp is introduced through six of the seven pathways considered here, but some of the pathways are specific to certain countries. This is the case with the common carp introduced to several countries via aquaculture (e.g., Australia, Shearer and Mulley, 1978;Varadi and Gorda, 2021), to New Zealand and South Africa for ornamental purposes [START_REF] De Moor | Atlas of alien and translocated indigenous aquatic animals in southern Africa[END_REF]Hanchet, 1990, Froese andPauly, 2019;Varadi and Gorda, 2021), and to Finland for angling (Froese and Pauly, 2019). Species introduced to a high number of countries also tend to have a high level of parental care and a high number of diets: for example, Oreochromis mossambicus and Oreochromis niloticus, respectively introduced to 97 and 94 countries, are bearers and have at least four diets (Froese and Pauly, 2019). This result confirms our initial hypothesis, as these two characteristics have already been highlighted in previous studies, although only at the state or country scale and for the establishment step (Marchetti et al., 2004a in California;Tonella et al., 2018 in Brazil;Chan et al., 2021 in Singapore;Lawson and Hill, 2021 in Peninsular Florida). Nonetheless, the role played by parental care in the introduction step of the invasion process has not yet been reported, and the underlying mechanisms remain to be clarified (e.g., Marchetti et al., 2004a). One possible explanation could be that species with high parental care tend to be more introduced, because their reproduction is easier in captivity. For instance, several species of Poecilids (e.g., guppies,

Poecilia reticulata) and Cichlids (e.g. Haplochromis sp. or Cichlasoma sp.) are popular aquarium fish known to be highly prolific and easy to rear [START_REF] Bianchi | L'aquarium tropical d'eau douce[END_REF].

Establishment

For species established in many countries, we found characteristics similar to the introduction step: high number of pathways, high parental care, and high number of diets. The high number of introduction pathways is linked to the high propagule pressure, which is known to be one of the main characteristics of invasion success [START_REF] Jeschke | Determinants of vertebrate invasion success in Europe and North America[END_REF]. High parental care maximizes offspring survival in the presence of competitors, thus providing an advantage that can favor establishment [START_REF] Levine | Elton Revisited : A Review of Evidence Linking Diversity and Invasibility[END_REF]. Moreover, generalist diets allow introduced species to adapt in different environments and thus provide the opportunity to establish in a wide range of environments (Tonella et al., 2018).

Despite this common overall pattern of introduction and establishment characteristics, we found several noteworthy differences. For example, although species introduced through the aquaculture pathway are introduced in many countries, their establishment success remains limited. This result is counterintuitive, as aquaculture is recognized as the most important introduction pathway of non-native freshwater fish [START_REF] Gozlan | Current knowledge on nonnative freshwater fish introductions[END_REF]. Our results suggest that even though aquaculture allows the establishment of many different species, it does not result in these species establishing in many different countries. This trend can be explained by the concentration of aquaculture production in Asia, especially in China, which produces a higher diversity of species [START_REF] Metian | Mapping diversity of species in global aquaculture[END_REF]. The way in which the species are cultured in each country also affects the probabilities of establishment. For example, species reared in and escaping from natural ponds are more likely to establish, because the individuals often escape in high numbers [START_REF] Gu | Does aquaculture aggravate exotic fish invasions in the rivers of southern China?[END_REF]. This trend could also reflect the efficiency of management methods set by governments to limit or avoid fish escapes [START_REF] Kolar | Managing undesired or invading species. Inland fisheries management in North America[END_REF]. We can also hypothesize that some species introduced through aquaculture are not able to survive and reproduce in natural environments (e.g., East Asian carp in North Europe; [START_REF] Lehtonen | Alien Freshwater Fishes of Europe[END_REF].

Ecological impact

The variables influencing the number of countries where species have ecological impacts are distinct from those influencing the introduction and establishment steps. Contrary to our hypothesis, diet did not have a significant impact on the impact step. Fisheries, ornamental trade, and angling along with the diffusion of already established species were the major pathways favouring non-native species impacts. Surprisingly, the aquaculture pathway did not stand out as an important variable despite the substantial impact of some cultured fish. In fact, the impacts of fish introduced through aquaculture may be understudied due to their economic benefits [START_REF] Gozlan | Introduction of non-native freshwater fish : Is it all bad?[END_REF][START_REF] Haubrock | Knowledge gaps in economic costs of invasive alien fish worldwide[END_REF], which explains why aquaculture does not stand out as an important variable. For example, the channel catfish (Ictalurus punctatus) is known to be responsible for the decline of native species outside its native range [START_REF] Townsend | Assessment of the Environmental Risk Posed by an Exotic Fish : The Proposed Introduction of Channel Catfish (Ictalurus punctatus) to New Zealand[END_REF]. Though widely introduced in Brazil for aquaculture, no ecological impact has been recorded in FishBase for the species in this country [START_REF] Vitule | Introduction of non-native freshwater fish can certainly be bad[END_REF]Froese and Pauly, 2019). At the global scale, data on freshwater fish impacts are incomplete, which hinders the identification of important characteristics for this invasion step [START_REF] Vitule | Introduction of non-native freshwater fish can certainly be bad[END_REF].

Introduction pathways are not the only important variables for the impact step. Indeed, Siluriformes are introduced, established, and have impacts in many countries, but only if they have a broad diet. This tendency seems to be driven by a few species that have a broad diet and are present in a high number of countries (i.e., Clarias angilaris, Ictalurus punctatus, Ameiurus melas, Ameiurus nebulosus, Silurus glanis).

Importance of interactions between pathways and species characteristics

In this study, we highlighted differences in the species characteristics according to the introduction pathways. Preliminary analysis comparing introduced and non-introduced species highlighted the influence of introduction pathways on invasion success (Appendix 6).

Considering all the species, the overrepresentation of species native to the Palearctic and Sino-Oriental regions among the introduced species could be due to the influence of the two most important pathways: aquaculture and ornamental trade. Indeed, these regions are economically well developed, making them more prone to export fish species for the aquaculture (FAO, 2012). This may also be linked to the early development of aquaculture in these regions, in particular in the Palearctic region [START_REF] Balon | Origin and domestication of the wild carp, Cyprinus carpio : From Roman gourmets to the swimming flowers[END_REF]. With the development of aquaculture in tropical countries [START_REF] Garlock | A Global Blue Revolution : Aquaculture Growth Across Regions, Species, and Countries[END_REF], this trend is likely to spread throughout developing regions of the globe. Considering the models per pathway, the species introduced and established in many countries through aquaculture are similar to those of the global pool (i.e., high number of diets, high parental care). They also tend to be from the Cypriniformes order.

This can be explained by human selection. Fish from the Cypriniformes order such as carp have been cultured for centuries [START_REF] Balon | About the oldest domesticates among fishes[END_REF] and thus constitute the main species produced in global aquaculture (FAO, 2020).

However, species introduced and established in many countries through the ornamental trade are not hydrodynamic and are more often native to the Neotropical and Sino-Oriental regions.

These characteristics correspond to the description of the most popular aquarium fish such as Poeciliids and tetras [START_REF] Duggan | Popularity and Propagule Pressure : Determinants of Introduction and Establishment of Aquarium Fish[END_REF][START_REF] Gertzen | Quantifying invasion pathways : Fish introductions from the aquarium trade[END_REF], thus pointing to the strong influence of propagule pressure.

Limitations and recommendations for future studies

It is important to note that the similarity between the introduction and establishment steps can be partially explained by a detection bias: introductions that fail to establish have less chance of being reported than successful introductions [START_REF] Drake | Parental investment and fecundity, but not brain size, are associated with establishment success in introduced fishes[END_REF]. Nonetheless, a non-negligible number of failed introductions were reported here (90 out of 307). We used the number of countries where species are introduced, established, and have impacts as an indicator of alien success, although the size of the countries is highly variable, which implies possible biases.

Species established in many small countries are considered to be more established than species established in a limited number of large countries, even though they may both cover the same area. This bias could be corrected by using the number of basins, but we only have this information for the establishment step [START_REF] Tedesco | A global database on freshwater fish species occurrence in drainage basins[END_REF]. Nonetheless, the number of countries where species have become established is significantly and positively correlated to the number of basins, thus minimizing the importance of the bias (Appendix 8). Moreover, some of our results can vary at the local scale, because the characteristics of the recipient environment can significantly influence the outcome of an introduction [START_REF] Vila-Gispert | Life-history traits of invasive fish in small Mediterranean streams[END_REF]. To improve future studies, more data should to be collected in relation to the impact step as well as certain characteristics such as fecundity, which has been shown to influence the establishment of species at the local scale [START_REF] Vila-Gispert | Life-history traits of invasive fish in small Mediterranean streams[END_REF].

Conclusion

This study provides a comprehensive understanding of the characteristics that allow for the success of the whole invasion process. It highlights the importance of considering different invasion steps separately to account for the wide variety of extrinsic and intrinsic factors involved in invasion models and disentangle the effects of introduction pathways. These results can be useful in order to improve screening tools. For example, the invasiveness tool of FishBase only takes into account the introduction pathway and the climate adequacy between the native and recipient environment to determine the potential invasiveness of a species (Froese and Pauly, 2019). By contrast, our results stress the importance of considering a wider variety of characteristics. The findings also show the importance of determining not only the invasive status of a species but also the profile of species with the potential to invade large areas. Ultimately, this approach considering the different steps and pathways of invasion could be helpful to better identify the determinants of invasion success in other taxa [START_REF] Capellini | The role of life history traits in mammalian invasion success[END_REF].

Figure 1 :

 1 Figure 1: Estimates (with standard errors) of significant variables resulting from the generalized linear

Figure 2 :

 2 Figure 2: Estimates (with their standard errors) of significant variables resulting from the generalized

Figure 3 :

 3 Figure 3: Estimates (with their standard errors) of significant variables resulting from the generalized

Figure 4 :

 4 Figure 4: Main important characteristics favoring the success of each step of the invasion process.

Table 1 :

 1 Variable descriptions.

	Variable type	Variable	Variable modalities	Hypothesis / Justification

Data availability statement:

All the R code necessary to generate the data and the results present in the paper will be available on GitHub after the acceptance of the paper. Used data also include open access data : (i) FishBase (Froese and Pauly, 2019, version 19.04, accessed with the "rfishbase" R package; Boettiger et al., 2012); (ii) the FISHMORPH morphological database [START_REF] Brosse | FISHMORPH : A global database on morphological traits of freshwater fishes[END_REF]; (iii) the database on freshwater fish occurrences complied by [START_REF] Tedesco | A global database on freshwater fish species occurrence in drainage basins[END_REF]; (iv) the global biogeographical regions of freshwater fish [START_REF] Leroy | Global biogeographical regions of freshwater fish species[END_REF]; and (v) the world climate database WorldClim [START_REF] Fick | WorldClim 2 : New 1-km spatial resolution climate surfaces for global land areas[END_REF].

Boxplots represent the estimates (without standard errors) of 100 models. We varied the main diet of species with several main diets and the main native bioregion of species with several main native bioregions. The color gradient represents the number of models in which the considered variable is significant (1: blue, 100: red). "TL" refers to total length.

Appendix 5: Main characteristics to succeed at each invasion step for the global pool and for species introduced through the ornamental and aquaculture pathways

Appendix 6: Differences in characteristics between introduced and non-introduced species

Methods

Introduction status

We took as introduced all species introduced to at least one location (i.e., species with at least one location listed in the "TO" column of the introduction() table). It should be noted that some species were simply imported to the location without being introduced to the wild. These species were impossible to separate from others, although they represent only a very small part of the data (Nicolas Bally, pers. com.). Thus, these were taken as species introduced to the wild.

Statistical analysis

To compare the characteristics of the introduced species with those of the non-introduced species, we conducted univariate comparisons between the introduced and non-introduced species for each characteristic. First, we directly compared introduced versus non-introduced species. Second, we accounted for the class imbalance between non-introduced species (majority class) and introduced species (minority class) by performing a repeated random subsampling approach. In this latter approach, we reduced the majority class (non-introduced species) to a random sample of size equal to the minority class (introduced species) and then made 999 repetitions. To test the significance of the results, we used a Fisher test for each modality when the considered characteristic was a qualitative variable and a Wilcoxon test for quantitative variables. We considered a test to be significant when p<0.05 (see Appendix 7 for the p-values of each test).

We performed these analyses for the entire pool of species and then specifically analyzed each pathway in order to detect any interactions between pathways and species characteristics. As the main diet and main native region of some species were chosen randomly from several possibilities, we also performed sensitivity analysis on the main diet and main native region.

To do so, we randomly selected (100 repetitions) the main diet and main native region between the different modalities for the concerned species.

Results

We examined the characteristics that were overrepresented in the introduced species pool compared to the non-introduced pool of species (Fig. 1). We found that introduced species had a higher temperature amplitude in their native basins, a higher number of diets and native regions, and were more often used by humans than non-introduced ones. These differences were found in the majority of the considered introduction pathways, except for the ornamental and species control pathways.

In addition, the native regions of the introduced species strongly differed for the different pathways (Fig. S1). For example, species mainly native to the Palearctic and Sino-Oriental regions were more represented among introduced species than non-introduced ones in the global pool. By contrast, the Neotropical region was more represented among species introduced through the ornamental trade pathway compared to other species. Species introduced by the ornamental pathway also had ventral pectoral fins and were rather small (compared to long fish introduced by fisheries and sport/angling). Accidentally introduced species tended to have lateral pectoral fins and were more represented in the Cypriniformes order than other fish. Concerning species introduced by sport/angling, they were more represented in the guarder strategy for parental care and in the nekton category for main diet compared to other fish. Finally, species introduced for species control were more represented in the bearer strategy for parental care, in the Cyprinodontiformes order, and had lateral pectoral fins compared to other species.

Figure S1: Results of Wilcoxon tests and F-tests per modality for each variable and each introduction pathway (see Appendix 7 for p-values). Red (blue) color indicates when introduced

species are significantly more (less) represented or have a significantly higher (lower) value than non-introduced species using comparisons with all species. The gradient of colors represents the proportion of significant tests using the resample method. Only variables with a significant difference are presented. The p-values of tests with all species are available in the Appendix 7. It is important to note that these results do not describe the main characteristics of the introduced species (see Appendix 6bis) but rather the differences between the introduced and non-introduced species.

Discussion

We demonstrated the importance of a high number of diets and a high temperature tolerance to differentiate introduced species from non-introduced ones at the global scale. These findings are supported by the literature at the local scale (e.g., North America, Kolar and Lodge, 2002;Parana River, Tonella et al., 2018). In addition, human use is unsurprisingly related to a greater likelihood of introduction and has already been highlighted to differentiate invasive and native species [START_REF] Alcaraz | Profiling invasive fish species : The importance of phylogeny and human use: Profiling invasive fish[END_REF]. Moreover, species from a higher number of native regions were also more introduced, perhaps because they have greater opportunities to be in contact with human activities. Nonetheless, some species with only one native bioregion can also be introduced in numerous countries: for example, the common carp (Cyprinus carpio), native to the Sino-Oriental region, has the highest number of introduced countries in our pool (i.e. 133 countries).

Appendix 6bis: Representation of qualitative data

Overall, successfully introduced species were mainly used by humans, adopted a non-guarder strategy for parental care, were represented by the Perciformes or Cypriniformes orders, and had a zoobenthos main diet. The only exceptions were for species introduced through the species control pathway. Species introduced for species control were mainly from the Cyprinodontiformes order and adopted a bearer strategy for parental care (Appendix 6bis, A, C, D, E). We found that species mainly native to the Sino-Oriental, Neotropical, and Nearctic regions were frequently introduced species (Appendix 6bis, B). The cells in white correspond to the p-values of the direct comparisons between introduced and non-introduced species for each characteristic. The cells in gray show the proportion of significant tests performed using the repeated random subsampling approach. With this latter approach, we reduced the majority class (non-introduced species) to a random sample of size equal to the minority class (introduced species) and performed 999 repetitions.

A.

Amplitudetemp