L Ollivier
email: louis.ollivier@free.fr

European pig genetic diversity: a minireview*

Keywords: pig breeds, genetic marker, diversity, allelic richness Implications

An evaluation of the European pig diversity has been carried on by several countries, with the support of the European Union over the period of 1994 to 2000. This article presents an overview of the results of this investigation, focussing on two genetic marker techniques, namely microsatellites (MS) and amplification of fragment length polymorphism (AFLP). Nearly 200 loci were characterised on about 50 individuals from each of 59 to 71 breeds, according to the marker considered. The analysis of diversity, based on genetic distances, led to similar conclusions for the two marker types (MS and AFLP), in spite of a markedly lower total diversity of AFLP compared to MS. The analysis of the MS loci showed that the allelic diversity pattern among breeds was quasiindependent from the diversity pattern based on allele frequencies. Genetic distances showed no particular clustering of local with international breeds, confirming the genetic uniqueness of the European local breeds compared to mainstream international breeds. The taxonomy of the local breeds revealed a cluster of the Iberian type breeds, in contrast with a wider dispersal of the breeds from other countries. Phylogeny often disagreed with documented breeds' history, showing the complex migration/admixture patterns which underlie the breeds' relationships. Methodologies developed in this investigation as well as the database and the DNA depository created should provide support for further innovative research in the field of domestic animal diversity management.

Introduction

The current state of the pig genetic resources in Europe is characterised by the existence of many local breeds, mostly rare, and a few intensively selected breeds of international status (e.g. Large White, Landrace, Pie ´train, etc.). Such a situation makes it of particular interest to assess the level of genetic diversity that is present in Europe, in order to preserve genetic variation for traits likely to be the targets of current or future selection programmes. With this aim in mind, collaborative programmes were launched with the support of the European Commission (EC) in the early 90s. A large set of European pig breeds was sampled and genetic markers used to assess diversity. The purpose of this paper is to outline the history and scope of various European programmes following earlier studies of genetic polymorphisms in the pig. The results obtained in the partitioning of diversity, within and among the breeds sampled, will be reviewed, and the relationships among breeds evidenced will be discussed. The emphasis in these investigations is on the exploitation of DNA marker information, which raises the important issue of marker neutrality and the relevance of molecular variation for quantitative trait diversity. Finally, lessons and opportunities offered will be briefly discussed.

European programmes

Research on genetic polymorphisms in farm animals has a long history. For many years, it has been limited to blood groups, later followed by starch gel electrophoresis of proteins, so-called biochemical polymorphisms. A review of the pig genetic polymorphisms in the early 80s can be found in [START_REF] Ollivier | Pig genetics: a review[END_REF]. In the early 90s, DNA sequence variation started being intensively investigated and detailed porcine genetic maps were established, mainly including microsatellites (MS) but also allowing accurate mapping of several blood group and biochemical polymorphisms (Ollivier et al., 2001a).

The use of genetic markers for comparing breeds of pigs started in the late 60s [START_REF] Major | Untersuchungen u ¨ber die verwandtschaftlichen Beziehungen zwischen verschiedenen europa ¨ischen Landrassepopulationen mit Hilfe von Blutgruppenfaktoren[END_REF][START_REF] Dinklage | Blutgruppen-and Serumproteinpolymorphisms bei verchiedenen in Deutschland vorhandenen Schweinerassen[END_REF]. It is also worth recalling the extensive literature devoted to comparing domestic breeds to wild pigs from various continents, with a view to trace the possible origin of our present breeds. The shift of emphasis towards genetic diversity could only come with the development of efficient molecular genetic tools. A major contribution to the making of genetic maps was made through the Pig Gene Mapping Project (PiGMaP) supported by the EC over the period of 1991-96 [START_REF] Archibald | The PiGMaP consortium linkage map of the Pig (Sus scrofa)[END_REF]. In the second phase of this project, a pilot study on genetic diversity was undertaken following the recommendations made by a working group convened by FAO (Barker et al., 1993[START_REF] Barker | Secondary Guidelines for Development of National Farm Animal Genetic Resources Management Plans. Measurement of Domestic Animal Diversity (MoDAD): Original Working Group Report[END_REF]. The results obtained in this study, covering 18 MS markers, were published by [START_REF] Laval | Genetic diversity of eleven European pig breeds[END_REF].

Based on the experience gained in PiGMaP, a new programme was launched by the EC in 1998, entitled 'Characterisation of genetic variation in the European pig to facilitate the maintenance and exploitation of biodiversity' (in brief PigBioDiv). The main objective of PigBioDiv was to evaluate genetic diversity, considering both commercial populations and local breeds, by providing the reference data necessary to estimate within-breed as well as between-breed genetic variability. This was achieved by sampling 50 individuals from different breeds and lines, and determining diversity at DNA level. The emphasis was on standard DNA marker technologies, such as simple sequence repeat (so-called MS) and amplification of fragment length polymorphism (AFLP), and on the use of high throughput genotyping devices (for details of the project see: Groenen et al., 2003; Ollivier et al., 2003; Plastow et al., 2003). The essential results can be found in SanCristobal et al. (2006a) for MS, SanCristobal et al. (2006b) and Foulley et al. (2006) for AFLP, and Ollivier et al. (2005) for an overall analysis of genetic diversity, cumulating MS (PiG-MaP and PigBioDiv breeds) and AFLP (PigBioDiv breeds only) information. Some supplementary information can be obtained on a publicly available website (http://www.projects.roslin.ac. uk/pigbiodiv/publications.html).

Pig genetic diversity evaluation was also included among the tasks of another EC-funded programme entitled 'European gene banking project for pig genetic resources', in the framework of the EC regulation 1467/94 on genetic resources (RESGEN), over 1996-98 (Ollivier et al., 2001aand 2001b). This study made use of some MS results obtained in PiGMaP and PigBioDiv. More recently, a new EC pig biodiversity programme was prepared shortly after the completion of PigBioDiv, including Chinese partners, with the intention of having the European experience extended to China [START_REF] Blott | Characterisation of genetic variation in the pig breeds of China and Europe -The PigBioDiv2 project[END_REF]. An overview of the main features of those programmes is presented in Table 1, which clearly shows an increasing coverage over time of both the resources and the genome of the species.

Genetic and allelic diversity

In the diversity programmes of Table 1, a total of 72 breeds were sampled, as listed in Table 2. By combining the PiG-MaP and PigBioDiv data, a subset of 68 European domestic breeds was eventually analysed for both within-breed and between-breed diversity. These breeds belonged to three categories, namely local breeds (29 breeds), national varieties of international breeds (18 breeds) and commercial lines from private breeding companies (21 lines). As shown in Table 2, two additional European domestic breeds were sampled but could not be analysed.

Genetic diversity within breed

The within-breed diversity has been analysed for AFLP and MS. The average expected heterozygosity for each category of breed showed a similar tendency for both markers, namely lower within-breed diversity in local breeds and commercial lines as compared to international breeds. This observation appears to be in keeping with what is known of the average effective size of the breeds and lines of each category, though rather large variations appeared between populations of the same category. Care should therefore be taken when comparing individual breed heterozygosities, given their rather large standard error of estimation. It should also be noted that heterozygosities expected under Hardy-Weinberg equilibrium were being considered, though this assumption could only be statistically tested for MS. There it was rejected (at P , 0.051 ) for 15 breeds, which mostly showed a deficit of heterozygotes.

A well known difficulty with MS, however, is occasional failure of amplification leading to null alleles and to a spurious enhancing of heterozygotes deficit [START_REF] Chakraborty | Apparent heterozygote deficiencies observed in DNA typing data and their implications in forensic applications[END_REF]. Breed expected heterozygosities were converted into breed contributions to within-breed diversity, allowing a within-breed diversity breakdown over the three categories of breeds defined above (see CWs in Figure 1). Contributions to within-breed diversity must add up to zero over breeds, and thus necessarily include some negative values, since the extinction of a highly homozygous breed raises the average heterozygosity of the remaining ones.

Genetic diversity between breeds

When analysing between-breed diversity, individual breed contributions to diversity may be derived from any set of distances. In a context of species conservation, [START_REF] Weitzman | On diversity[END_REF]1993) showed how to derive a diversity function (V) from a set of genetic distances, in order to evaluate the relative loss of diversity resulting from the extinction of any given species. This loss is taken to represent its contribution to genetic diversity. Weitzman also showed that the algorithm leading to V generates a rooted tree, which may be interpreted as a taxonomic tree, whose branch lengths measure the diversity lost when the corresponding species goes extinct (see next section on taxonomy). The approach has been extended to the situation of livestock breeds diversity by [START_REF] Thaon D'arnoldi | An overview of the Weitzman approach to diversity[END_REF], and software has been developed in the framework of PigBioDiv for implementing the calculations, down to the drawing of the taxonomic tree (Derban et al., 2002(Derban et al., -2005)).

This method has already been used in most farm animal species and shown to be helpful for setting conservation priorities among endangered breeds, as reviewed by [START_REF] Ollivier | Adaptation and fitness in animal populations: evolutionary and breeding perspectives on genetic resource management[END_REF]. Between-breed diversity was partitioned in that way among the 70 breeds of PigBioDiv, and a breakdown among the three categories could thus be achieved and compared to the corresponding breakdown for within-breed diversity. As shown in Figure 1, the breed categories ranked in a reverse order for between-compared to within-breed diversity, with higher differences between categories for the former. About half of the between-breed diversity could be assigned to the local breeds. Similar examples showing large contributions of 'native' breeds have been reported in cattle and sheep [START_REF] Tapio | Prioritization for conservation of northern European cattle breeds based on analysis of microsatellite[END_REF]. As explained above, some within-breed contributions may be negative. In contrast, the diversity function of Weitzman is a monotonously increasing function of the number of breeds and cannot yield negative contributions.

Comparisons between markers Microsatellites and AFLP are both numerous and dispersed over the pig genome, making them both suitable for biodiversity analyses. Overall genetic diversity in AFLP was considerably below MS: 0.12 v. 0.56 and 0.11 v. 0.23, respectively, for expected heterozygosity and Wright fixation index (F ST ) (Foulley et al., 2006). In spite of these differences in total diversity, the individual breed contributions to both diversities (within and between) were positively correlated between the two markers, which is confirmed by the similarity between the MS and AFLP graphs of Figure 1. The correlations (r 5 0.5), however, were moderate and somewhat lower than would be expected if the two markers' evolutions had been governed mainly by genetic drift. This suggests that the two markers may carry different diversity information (Foulley et al., 2006). An illustration is provided by the Italian breeds of PigBioDiv shown in Figure 2. In this subset, the international breeds (Duroc (DU), Landrace (LR) and Large White (LW)) contributed much more to AFLP diversity than to MS diversity, whereas the reverse appeared for the local breeds (Calabrese (CA), Cinta Senese (CS) and Casertana (CT)).

Allelic diversity

The number of alleles per locus, termed allelic richness, is a diversity measure of great interest in conservation genetics. While heterozygosity is related to the immediate response to selection, the long-term response is affected by the number of alleles (see the review of [START_REF] Barker | Conservation and management of genetic diversity: a domestic animal perspective[END_REF]). Marker allelic richness is also a useful criterion, as shown by the effectiveness of marker-assisted maximisation of the number of marker alleles conserved for retaining the maximum number of neutral and non-neutral alleles [START_REF] Bataillon | Neutral genetic markers and conservation genetics: simulated germplasm collections[END_REF]. The number of alleles observed in a breed sample depends on sample size (N). Fair comparisons between breeds then require equal sample sizes, or some way of correcting the number observed for sample size. Techniques used in ecology to study species diversity allow making fair comparisons, e.g. by applying the 'rarefaction' method. The idea of rarefaction is to estimate allelic richness by the number of alleles expected in a sample of specified size, g, which is the smallest N of all breeds examined at a given locus (El [START_REF] Mousadik | High level of genetic differentiation for allelic richness among populations of the argan tree (Argania spinosa (L.) Skeels) endemic to Morocco[END_REF]. Another possibility is to use an 'extrapolation' method, proposed by [START_REF] Foulley | Estimating allelic richness and its diversity[END_REF], who compared it to rarefaction on the PigBioDiv breeds.

The concept of allelic richness leads to the slightly different concept of allelic diversity, which refers to the existence of alleles specific to some breeds, since a high number of different alleles in a breed does not automatically guarantee their originality. The alleles present in one breed and absent in all others are called 'private' alleles. Equivalently to the above definition of breed contribution to genetic diversity, the number of private alleles in a breed is a measure of its contribution to allelic diversity. This number has also to be corrected for sample size. This can be done either through rarefaction or extrapolation. The Italian example given in Figure 3 shows that the number corrected may considerably deviate from the observed number, in either direction. Figure 3 also shows that the Black Sicilian pig (NS), which harbours the largest number of private alleles, is not among the highest contributing breeds to MS diversity in Figure 2. This example illustrates the need to distinguish allelic diversity, where allele uniqueness is at stake, from the classical genetic diversity concept, based on allele frequency. The quasi-independence found between the two types of diversity over the PigBioDiv breeds may apply to other species as well, as suggested by [START_REF] Foulley | Estimating allelic richness and its diversity[END_REF].

European pig diversity

Linkage disequilibrium

Linkage disequilibrium (LD) is a non-random association of genes at different loci, known to decrease rapidly with increasing map distance of the loci considered. Detecting significant LD therefore needs narrowly spaced genetic markers, not available until recently. With an average map distance of 35 cM between neighbouring markers among the 50 MS selected in PigBioDiv (see Table 1 in [START_REF] Groenen | The use of microsatellites genotyping for population studies in the pig with individual and pooled samples[END_REF], the MS data collected in this study could not be expected to allow any precise evaluation of LD extent in the pig. One of the earliest studies of LD in pigs actually used 15 MS, spaced 5 cM on average, and was able to show significant LDs on two pig chromosomes [START_REF] Nsengimana | Linkage disequilibrium in the domestic pig[END_REF]. The increasing availability of single nucleotide polymorphisms (SNPs) in domestic animals will open the way to high-density genetic maps comparable to those achieved in humans [START_REF] Akey | Interrogating a highdensity SNP map for signatures of natural selection[END_REF]. A recent comparison of 10 European and 10 Chinese breeds, and a European wild boar, bearing on 371 SNPs, revealed more extended LD in Europe compared to China, with the wild boar in an intermediate position [START_REF] Amaral | Linkage equilibrium decay and haplotype block structure in the pig[END_REF]. Interestingly, a very highly significant interaction was evidenced between breed and genome region, which might reflect differential selection pressures across genomic regions among breeds.

Taxonomy and breed clustering

In the previous section, it has been shown how genetic distances were used in PigBioDiv to analyse genetic diversity. Another classical use of genetic distances is the drawing of trees, often called phylogenetic trees. The term implicitly refers to evolution theory where diversity arises from speciation, i.e. the division of one ancestor species into two new species. Quite apart from the possible phylogenetic ambiguity of molecular data, as discussed for instance by [START_REF] Smouse | To tree or not to tree[END_REF], such a pattern of evolution can hardly apply to farm animal breeds, except in particular short-term situations when one breed (or line) happens to be subdivided into two new ones. Domestic breeds' evolution cannot, in general, be viewed as the result of a tree-like branching process. The trees drawn must be considered as telling the evolutionary story that best fits the diversity observed but not necessarily as telling the 'true' story [START_REF] Weitzman | On diversity[END_REF]. Quite complex migrationadmixture patterns usually prevail and the trees are best viewed as classification tools, showing taxonomies rather than phylogenies. The trees drawn from the PigBioDiv MS and AFLP data showed a typical clustering of the commercial lines around their respective international breed of reference, but no clustering of local breeds with international breeds (Foulley et al., 2006; SanCristobal et al., 2006a), in agreement with the local breeds' 'uniqueness' shown in Figure 1.

The taxonomy of the 30 local breeds investigated in the European projects is given in Figure 4. This is the rooted tree generated by applying V to this subset of breeds (see previous section). The longest branch is that of the French Basque, the breed contributing most to European between-breed diversity. The graph also shows the non-additivity of individual breed contributions, since the joint contribution of Gloucester Old Spots (GBGO) and Berkshire (GBBK) for example, represented by the abscissa of their node (about 0.3), is much less than the sum of their individual branch lengths.

Figure 4 shows no marked geographical clustering of the British, French, German and Italian breeds, in contrast with the Iberian cluster evidenced, which could have been expected from the common origin of the Retinto (RE) and Negro Iberico (NI) breeds. These, in fact, may be seen as two strains of the Iberian breed. To be noted, however, is the distinctive position of the other two Spanish breeds, the Manchado de Jabugo (MJ), known to be somewhat apart from the Iberian group [START_REF] Martinez | Genetic structure of the Iberian pig breed using microsatellites[END_REF], and the Negro Canario (NC), for which there is evidence of some African connection (Juan-Vicente Delgado, personal communication).

Particularly surprising is the close genetic vicinity of breeds originating from two islands as distant as Guadeloupe (FRCR) and Sicily (ITNS). It is also of interest to compare the MS-based clustering of Figure 4 with the history of the world pig breeds as reported in the popular handbook of [START_REF] Porter | A handbook to the breeds of the world[END_REF]. In several cases, the documented history of 'old' breeds is not supported by the clustering observed. The Cre ´ole pig (FRCR), for instance, is quite far away from the Large Black (GBLB), reported as being among its main founding breeds. Similarly, the Polish Pulawska (PLPU), reportedly originating from a cross with GBBK is quite distant from this breed. No trace appears to remain of the reported proximity of the Neapolitan pig, presently represented by the Italian Casertana (ITCT) breed, to several English breeds. This probably reflects the continuously blurred phylogeny of pig breeds as a consequence of complex migration-admixture patterns, varying both in time and space.

Molecular and quantitative trait diversity

Breed diversity is probably the most useful information that can be drawn from a set of genetic distances in a context of conservation. This leaves open the question of the relevance of neutral marker diversity (anonymous) with regard to quantitative trait diversity (functional). One should, however, avoid concluding on the neutrality of the diversity measured from the supposed intrinsic neutrality of the markers used. We know that neutral genes can be affected by selection applied to neighbouring genes, a phenomenon known as gene hitchhiking (Maynard [START_REF] Smith | The hitch-hiking effect of a favourable gene[END_REF]. Selection acts on the whole genome and diversity is generated under the dynamics of multi-locus systems. This situation is in fact exploited, in reverse, in marker-assisted selection procedures using markers close to quantitative trait loci (QTL). Quite extensive QTL maps are now available for most farm animals, including the pig. Due to their adequate coverage of the pig genome, most of the 50 MS used in PigBioDiv have indeed been shown to be linked to a large number of quantitative traits (Ollivier and Foulley, 2009 2 ). One would then expect to find some correlation between marker and quantitative trait diversity, particularly for those markers closely linked to QTL and in LD with the latter.

The testing of marker neutrality, however, is a challenging task. This is a field of evolutionary biology which has been extensively investigated for many years, and particularly with the recent advent of genome scans of DNA polymorphisms to elucidate the genetic basis of adaptive divergence in natural populations (reviewed, among others, by [START_REF] Storz | Using genome scans of DNA polymorphism to infer adaptive population divergence[END_REF]. Similarly, the adaptation of domestic breeds to local conditions or to specific production objectives is expected to generate increased between-breed diversity and/or decreased within-breed diversity at those loci underlying the traits under selection, and at nearby neutral marker loci.

Differentiation between populations, as measured by F ST , is the basis of the test of selective neutrality proposed by [START_REF] Lewontin | Distribution of gene frequency as a test of the theory of the selective neutrality of polymorphisms[END_REF]. The basic argument behind this test is that, under the null hypothesis of neutrality, differentiation at all loci should be the same. The observed variance of F ST across marker loci can thus be tested against its expected value under the assumption of neutrality. Several improvements of the test have been proposed (reviewed by [START_REF] Ollivier | Adaptation and fitness in animal populations: evolutionary and breeding perspectives on genetic resource management[END_REF], essentially for taking into account the pattern of relationship among populations. Robertson's prediction (1975) that any 'structured' relationship will tend to increase the variance of F ST has indeed been confirmed in PigBioDiv. For both MS and AFLP, a lesser departure from neutrality was observed by removing half of the breeds in order to approximate a star-like pattern of phylogeny (Foulley et al., 2006). Nevertheless, after correction for this effect, the Lewontin-Krakauer (LK) test showed highly significant departures from neutrality for both markers, particularly large for AFLP. Methods for distinguishing loci under selection from neutral loci require assumptions on the demographic history of the populations and may be sensitive to the model implemented. The above modifications of the LK test preserve its advantage of being a model-free approach based on detecting outlier loci. This type of approach is likely to prevail when a large number of loci will be available, as with the SNP study by [START_REF] Akey | Interrogating a highdensity SNP map for signatures of natural selection[END_REF] in human populations. Encouraging results have, however, been obtained in a model-based approach using a Bayesian regression method [START_REF] Beaumont | Identifying adaptive genetic divergence among populations from genome scans[END_REF].

The neutrality tests, based on relative levels of diversity within populations, exploit the reduction of variability around a selected locus due to hitchhiking, a phenomenon called 'selective sweep [START_REF] Schlo ¨tterer | Polymorphism and locus-specific effects on polymorphism at micosatellite loci in natural Drosophila melanogaster populations[END_REF] proposed a test based on the variance of repeat number at MS loci. This test, however, may be sensitive to the demography-mutation model assumed. A more robust test can be performed by comparing groups of populations. The test statistic is the log of the ratio of variance in repeat number in two groups [START_REF] Schlo ¨tterer | A microsatellite-based multilocus screen for the identification of local selective sweeps[END_REF]. An application of this test to the PigBioDiv data showed the existence of 'outlier' loci with contrasting allele size distributions between groups of breeds, indicative of selective sweeps [START_REF] Ollivier | Adaptation and fitness in animal populations: evolutionary and breeding perspectives on genetic resource management[END_REF].

Lessons and opportunities offered

PigBioDiv was one of the 'demonstration projects' introduced in the life science and technologies programmes of EC as a 'mechanism aimed at fostering the adoption of research results in real-life practice' (Le Dour et al., 2000). PigBioDiv's objective was indeed to demonstrate the applicability of molecular biology tools for evaluating pig genetic diversity. Use was made of two standard marker technologies, and a wide spectrum of pig populations was examined. The activities pursued have been successful in making advances in the basic experimental design, operational modalities and analytical procedures for the broadscale evaluation of animal genetic resources. The project has also demonstrated how effectively commercial and public sector entities, and research staff can work together. Useful guidelines for future biodiversity projects were thus provided. Some prospects opened by further exploitation of the results will now be briefly discussed.

Methodology

This work has been a source of methodological developments on various classical concepts related to genetic diversity evaluation, such as Wright's fixation indices, genetic distances and the Weitzman approach to diversity [START_REF] Ollivier | Aggregate diversity: new approach combining within-and between-breed diversity[END_REF]. In particular, the difficulties of analysis of dominant marker data such as AFLP have been thoroughly investigated. For that type of markers, Foulley et al. (2006) could recommend the moment-based approach of [START_REF] Hill | Moment estimation of population diversity and genetic distance from data on recessive markers[END_REF] instead of the currently used procedures, in order to avoid potentially considerable biases in allele frequency and genetic diversity estimates. [START_REF] Bonin | Statistical analysis of amplified fragment length polymorphism: a toolbar for molecular ecologists and evolutionists[END_REF] also comment on the considerable differences between the latter results and those obtained with the square root method by SanCristobal et al. (2006b) on the same data, suggesting that the method of [START_REF] Hill | Moment estimation of population diversity and genetic distance from data on recessive markers[END_REF] may be particularly helpful in cases of low levels of polymorphism. Further methodological developments can be foreseen for marker-based assignment and kinship estimation. Measuring genetic diversity in farm animals, however, still remains a challenge. Some insight into the multiple facets of this endeavour is given in the review of [START_REF] Ollivier | Adaptation and fitness in animal populations: evolutionary and breeding perspectives on genetic resource management[END_REF].

Microsatellite individual genotyping

The advantages of MS for evaluating diversity have now been known for a long time. Their abundance, wide dispersion over the genome and highly automated characterisation make them a marker of choice. Difficulties, however, have been recognised in harmonising results from different laboratories, which requires standardisation of allele size. A coding system has been established in PigBioDiv, based on the mean and range of allele size compared to four control samples used in PiGMaP [START_REF] Ollivier | Characterisation of genetic variation in the European pig to facilitate the maintenance and exploitation of biodiversity[END_REF].

DNA pool genotyping Microsatellite genotyping on DNA pools, known to be a cost-effective means to estimate allele frequencies, was also investigated in PigBioDiv. The need to select markers adapted to this technique [START_REF] Groenen | The use of microsatellites genotyping for population studies in the pig with individual and pooled samples[END_REF] and other technical difficulties restricted the typing to 20 out of the 50 markers used in individual typing. The technique is known to produce fluorescence peaks, which are clearly artefacts, as confirmed in this study by the large excess of peaks compared to the number of alleles identified on the same breeds. Consequently, as shown in Table 3, expected heterozygosities were considerably larger and Reynolds distances lower, and both less variable, when based on peak frequencies observed on DNA pools compared to allele frequencies in individual samples from the same 22 breeds. In addition, the correlations in Table 3 show that peak frequencies cannot provide accurate prediction of the standard diversity parameters. Discarding supernumerary peaks, as [START_REF] Megens | Biodiversity of pig breeds from China and Europe estimated from pooled DNA samples: differences in microsatellite variation between two areas of domestication[END_REF] did on the same data, also led to poor predictions of diversity parameters and markedly lower bootstrap values in breed clustering compared to individual typing. A statistical procedure to estimate allele frequencies (as proposed, for instance, by [START_REF] Skalski | Evaluation of DNA pooling for the estimation of microsatellite allele frequencies: a case study using striped bass (Morone saxatilis)[END_REF]) appears, therefore, necessary in order to best exploit the information given by DNA pools.

A pig diversity database The Roslin Institute was chosen as the ultimate data repository site in PigBioDiv. A database was mounted on the Roslin webserver and the data collected during the project were made available to the participants created at http://www.databases.roslin.ac.uk/pigdbase/ Later on, a publicly available website was created at http://www.projects.roslin.ac.uk/pigbiodiv/publications.html, mentioned previously, for a wider dissemination of the Pig-BioDiv results, offering innovative opportunities to the pig industry [START_REF] Institute | A pig diversity database[END_REF]. Rules of access to this information have been defined in an agreement signed by the PigBioDiv parties, and put under the guidance of a specific committee (ConservPig Management Group) representing the interest of all parties. More information on the PigBioDiv results are available upon request to the present Chair of the Group 3 , or to the author. 3 Dr Lawrence Alderson at Lawrence@clltd.demon.co.uk Ollivier Some information on the PigBioDiv2 project [START_REF] Blott | Characterisation of genetic variation in the pig breeds of China and Europe -The PigBioDiv2 project[END_REF] is available at https://mysygen.sygeninternational.com/ portal/page?_pageid595,50664,95_50699&_dad5portal&_ schema5PORTAL A DNA bank During PigBioDiv, DNA has been collected over a set of 59 populations of pigs, originating from 13 European countries and including one Chinese breed. Part of this DNA has been stored in a duplicated DNA bank, at Roslin (UK) and Toulouse (France) in view of further research. The corresponding genotypes for 50 MS and 148 AFLP loci are stored in the database described earlier. Rules of access to this DNA have been defined by the PigBioDiv parties, and put under the guidance of the above-mentioned ConservPig Management Group. This DNA depository, together with the database including the corresponding sample information, should provide support for further innovative research in the field of domestic animal diversity management.

Figure 1 Figure 2

 12 Figure1Contribution (%) of each category of breed (Loc: local breed; Int: international breed; Com: commercial line) to between-breed diversity (CB), based on the Weitzman diversity function applied to Reynolds genetic distances[START_REF] Reynolds | Estimation of the coancestry coefficient: basis for a short-term genetic distance[END_REF], and within-breed diversity (CW), based on expected heterozygosity. MS: microsatellites on 68 European domestic breeds; AFLP: amplified fragment length polymorphism on 58 European domestic breeds. Adapted fromOllivier et al. (2005).

Figure 3

 3 Figure 3 Number of private alleles in seven Italian breeds (breed codes given in Figure 2): number of alleles 'private' relative to the seven breeds considered, totalled over 50 microsatellite loci.

Figure 4

 4 Figure 4 Weitzman tree of the 30 local breeds of PiGMaP and PigBioDiv, based on Reynolds distances (Reynolds et al., 1983) for microsatellites. The breeds (PiGMaP breeds in bold) are from -Czech Republic: CZPR Presticke; France: FRBA Basque, FRBY Bayeux (Breed not considered in the PigBioDiv scientific papers), FRCR Cre ´ole (Guadeloupe), FRGA Gascon, FRLI Limousin, FRNO Normand; Germany: DEAS Angler Sattelschwein, DEBB Bunte Bentheimer, DEMA Mangalica, DESH Schwa ¨bisch-Ha ¨llisches Schwein; Denmark: DKSO, Sortbroget; Italy: ITCA Calabrese, ITCS Cinta Senese, ITCT Casertana, ITNS Nera Siciliana; Poland: PLPU Pulawska; Portugal: PTBI Bisaro; Spain: ESNC Negro Canario, ESNI Negro Iberico, ESMJ Manchado de Jabugo, ESRE Retinto; Sweden: SELS Lindero ¨dssvin; United Kingdom: GBBK Berkshire, GBBL British Lop, GBBS British Saddleback, GBGO Gloucester Old Spots, GBLB Large Black, GBMW Middle White, GBTA Tamworth.

Table 1

 1 European collaborative programmes on pig biodiversity

			Number of	Number of breeds	Genetic markers
	Programme (contract no.)	Year	countries	individually sampled a	(no. of loci)	Results
	PiGMaP (BIO2-CT94-3044)	1994-1996	6	11	-Microsatellites (18)	Laval et al. (2000)
	RESGEN (RESGEN-CT95-012)	1996-1998	6	19	-Blood groups (13)	Ollivier et al. (2001a)
					-Biochemical
					polymorphisms (11)
					-Microsatellites (18)
	PigBioDiv1 (BIO4-CT98-0188)	1998-2000	15	59	-Microsatellites (50)	Foulley et al. (2006)
					-AFLP (148)	Ollivier et al. (2005)
						SanCristobal et al.
						(2006a and 2006b)
	PigBioDiv2 (QLK5-CT-2002-01059) 2003-2006	China	45	-Microsatellites (39)	Amaral et al. (2008)
					-SNP (371)	Megens et al. (2008)
					-Mitochondria and
					Y-chromosome genes
					-Trait genes
	AFLP 5 amplification of fragment length polymorphism; SNP 5single nucleotide polymorphism.

a See list in

Table 2 . Ollivier Table 2

 2Ollivier2 List of the European breeds sampled in the collaborative projects of Table1

	Country of origin	Breed/line name (company)	Category	RESGEN	PiGMaP	PigBioDiv
	Belgium	Belgian Pie ´train	I		3
	Czech Republic	Presticke	L	3
	Germany	Angler Sattelschwein	L	3
	Germany	Bunte Benheimer	L	3
	Germany	Duroc line (S)	C
	Germany	Hampshire line (BHZP)	C
	Germany	German Landrace	I		3
	Germany	Landrace line (BHZP)	C
	Germany	German Large White	I
	Germany	Large White line (BHZP)	C
	Germany	Mangalica	L
	Germany	German Pie ´train	I
	Germany	Schwa ¨bisch-Ha ¨llisches Schwein	L	3	3
	Denmark	Danish Landrace (contemporary)	I
	Denmark	Danish Landrace (1970)	I
	Denmark	Sortbroget	L		3
	Spain	Negro Canario	L	3
	Spain	Negro Iberico	L	3
	Spain	Manchado de Jabugo	L	3
	Spain	Retinto	L	3
	Finland	Finnish Landrace	I
	France	Basque	L	3	3
	France	Bayeux	L		3 (*)
	France	Cre ´ole (Guadeloupe)	L	3
	France	DRB synthetic line (SCAPAAG)	C
	France	Gascon	L	3	3
	France	Laconie synthetic line (PAL)	C
	France	Limousin	L	3	3
	France	French Landrace	I
	France	Landrace line (FH)	C
	France	French Large White (dam line)	I
	France	Large White line (FH)	C
	France	Large White line (PAL)	C
	France	French Large White (sire line)	I
	France	Normand (or Blanc de l'Ouest)	L	3	3
	France	French Pie ´train	I
	France	Pie ´train line (FH)	C
	France	Tia Meslan synthetic line (PAL)	C
	United Kingdom	Berkshire	L
	United Kingdom	British Lop	L
	United Kingdom	British Saddleback	L
	United Kingdom	Duroc line (PIC)	C
	United Kingdom	Gloucester Old Spots	L
	United Kingdom	Hampshire line (PIC)	C
	United Kingdom	Large Black	L
	United Kingdom	Leicoma synthetic line (PIC)	C
	United Kingdom	Landrace line (PIC)	C
	United Kingdom	Landrace line (PIC)	C
	United Kingdom	Landrace line (PIC)	C
	United Kingdom	Large White line (PIC)	C
	United Kingdom	Large White line (PIC)	C
	United Kingdom	Large White line (PIC)	C
	United Kingdom	Middle White	L
	United Kingdom	Pie ´train line (PIC)	C
	United Kingdom	Tamworth	L
	Iceland	Icelandic Landrace	I
	Italy	Calabrese	L	3
	Italy	Cinta Senese	L	3

Table 2 Continued

 2

	Country of origin	Breed/line name (company)	Category	RESGEN	PiGMaP	PigBioDiv
	Italy	Casertana	L	3		3
	Italy	Italian Duroc	I			3
	Italy	Italian Landrace	I			3
	Italy	Italian Large White	I			3
	Italy	Mora Romagnola	L	3		3 (**)
	Italy	Nera Siciliana	L	3		3
	The Netherlands	Dutch Large White (sire line)	I		3
	Norway	Norwegian Landrace	I			3
	Poland	Pulawska Spots	L	3		3
	Portugal	Bisaro	L			3
	Sweden	Swedish Landrace	I		3
	Sweden	Lindero ¨dssvin	L			3
	Sweden	Wild pig from Poland	Wild		3
	China	Meishan	Imported			3
	Total	72	(***)	19	12	60

The breeding companies are: BundesHybridZuchtProgram (BHZP), France Hybrides (FH), Pen Ar Lan (PAL), Pig Improvement Company (PIC), Schaumann (S) and Socie ´te ´Coope ´rative Agricole pour l'Assainissement et l'Ame ´lioration Ge ´ne ´tique du Cheptel Porcin (SCAPAAG). The breed categories are: local (L), international (I) or commercial lines (C). (*) Bayeux not analysed in

[START_REF] Laval | Genetic diversity of eleven European pig breeds[END_REF]

. (**) Mora Romagnola only pool-genotyped for microsatellites. (***) 31 Local, 18 International, 21 Commercial and 2 Other.

Table 3

 3 Comparison of expected heterozygosity and Reynolds genetic distances[START_REF] Reynolds | Estimation of the coancestry coefficient: basis for a short-term genetic distance[END_REF] obtained from individual (I) and pooled (P) DNA samples, typed for 20 microsatellites on 22 breeds (adapted from the PigBioDiv final report[START_REF] Ollivier | Characterisation of genetic variation in the European pig to facilitate the maintenance and exploitation of biodiversity[END_REF]

	Parameter	Expected heterozygosity Reynolds distances
	Mean
	I	0.55	0.24
	P	0.72 a	0.09
	Standard deviation
	I	0.05	0.08
	P	0.02	0.04
	Range
	I	0.46-0.66	0.06-0.45
	P	0.68-0.77	0.03-0.24
	Correlation I-P	0.88	0.87

a 0.77 on 52 European breeds reported by

[START_REF] Megens | Biodiversity of pig breeds from China and Europe estimated from pooled DNA samples: differences in microsatellite variation between two areas of domestication[END_REF]

.

Not 0.01 given in SanCristobal et al. (2006a).

From http://www.animalgenome.org/QTLdb European pig diversity

Acknowledgements

The author wishes to thank Roberta Davoli (Reggio Emilia), Juan-Vicente Delgado (Cordoba), Gustavo Gandini (Milan) and Jean-Louis Foulley (Jouy-en-Josas) for their help in the preparation of this article. Particular thanks should also go to Alan Archibald, Chris Haley and Andy Law (Roslin) for their care of the 'pigbiodiv' database. The research was supported by the EU contracts BIO2-CT94-3044, RESGEN-CT95-012 and BIO4-CT98-0188, which are gratefully acknowledged. Comments made by three anonymous referees have also been of great help.


Héloïse Gonzalo-Turpin

Nathalie Couix

Laurent Hazard

Rethinking Partnerships with the Aim of Producing Knowledge with Practical Relevance: a Case Study in the Field of Ecological Restoration

Keywords: conservation biology, genetic resources, local seeds, mode of knowledge production, native species, problem-finding, Pyrenees, seed transfer zones, stakeholders

Researchers in conservation biology and restoration ecology often work in partnership with local actors to increase the practical relevance of the knowledge they produce. Although an academic mode of knowledge production is essential in research for a better understanding of biological systems, it often fails to produce frameworks and methodologies having practical relevance that can be used in conservation and restoration programs. The involvement of researchers in collective plans of action is supposed to contribute to the production of a more contextualized form of knowledge. In this paper, we report our experience of partnership research in an ecological restoration project. We show that changing our mode of knowledge production to one that produces knowledge having more practical relevance requires a particular spectrum of partners and reflexive communication between all the partners. We advocate the need for participatory approaches that favor collective and reflexive processes of problem finding and problem solving in conservation and restoration projects. Putting such processes into practice is not only a challenge for researchers but also for their partners, and presupposes a profound transformation of their roles.

INTRODUCTION

The conservation and restoration of threatened biological systems has emerged as a major scientific and societal issue during the last decade. The challenge for conservation biologists and restoration ecologists is to produce knowledge that can be effectively implemented when dealing with this issue [START_REF] Higgs | The two-culture problem: ecological restoration and the integration of knowledge[END_REF][START_REF] Robinson | Conservation biology and real-world conservation[END_REF]). Although the use of an academic mode of knowledge production in research is essential for a better understanding of biological systems, it often fails to produce frameworks and methodologies of practical relevance that can be used in conservation and restoration programs (Geist and Galatowitsch 1999[START_REF] Gobster | The restoration and management of nature. A conference and forthcoming book explore restoration from the perspectives of the social sciences and humanities[END_REF][START_REF] Robinson | Conservation biology and real-world conservation[END_REF][START_REF] Cabin | Science-driven restoration: a square grid on a round earth?[END_REF]. Using [START_REF] Rhoades | The role of farmers in the creation of appropriate technology[END_REF] example, most scientists may know how potatoes grow but they fail to earn their living growing them as a farmer does. Even when research programs are designed to guide conservation or restoration actions, realworld complexities often limit the operational relevance of the academic mode of knowledge production [START_REF] Gobster | The restoration and management of nature. A conference and forthcoming book explore restoration from the perspectives of the social sciences and humanities[END_REF][START_REF] Robinson | Conservation biology and real-world conservation[END_REF][START_REF] Cabin | Science-driven restoration: a square grid on a round earth?[END_REF]). To increase the practical relevance of their research, more and more conservation biologists and restoration ecologists are collaborating with local actors who know the field. Without this partnership, scientists often fail to grasp the complexity and the specificity of a problem occurring at a given site [START_REF] Higgs | What is good ecological restoration?[END_REF], 2005, Chan et al. 2007). By collaborating with local partners, they can first collectively identify the local problems and then look for pertinent solutions for this given context. Paraphrasing [START_REF] Rhoades | The role of farmers in the creation of appropriate technology[END_REF], the research questions shift from the academic type -"how do potatoes grow?"-to more complex and transdisciplinary types-"how do we grow potatoes?" Conservation biology (CB) and restoration ecology (RE) paradigms acknowledge this real-world complexity (for CB, see [START_REF] Robinson | Conservation biology and real-world conservation[END_REF] for ER, see [START_REF] Choi | Restoration ecology to the future: a call for a new paradigm[END_REF][START_REF] Temperton | The recent double paradigm shift in restoration ecology[END_REF], in which human factors must be explicitly considered [START_REF] Robertson | Beyond biology: toward a more public ecology for conservation[END_REF]. http://www.ecologyandsociety.org/vol13/iss2/art53/ Several authors have proposed different theoretical frameworks concerning the form of knowledge production that emerges in partnership research (see review by [START_REF] Hessels | Re-thinking new knowledge production: a literature review and a research agenda[END_REF]. [START_REF] Gibbons | The new production of knowledge: the dynamics of science and research in contemporary societies[END_REF] and [START_REF] Nowotny | Rethinking science[END_REF] proposed a synthetic theory in which they identified two modes of knowledge production, Mode-1 and Mode-2. Mode-1 is carried out in a scientific, disciplinebased framework. It favors academic research, partially disconnected from its potential context of application. In the short term, Mode-1 is often irrelevant to the production of operational and socially relevant knowledge [START_REF] Nowotny | Rethinking science[END_REF]. In contrast, Mode-2 starts from the problems posed in their context of application, by the different stakeholders, and necessitates partnership research. Nevertheless, very few authors have reported their concrete experience of partnership research associated with their attempt to change their mode of knowledge production.

In this paper, we report our experience of partnership research in an ecological restoration project called Ecovars (www.ecovars2.fr). We became involved in this partnership to increase the practical relevance of the knowledge we produce by contextualizing our scientific research. However, we show that achieving a change in our mode of knowledge production (from Mode-1 to Mode-2) requires a particular configuration of the partnership and partners who are pro-active. Putting Mode-2 into practice is not only a challenge for researchers but also for their partners.

A CASE OF PARTNERSHIP RESEARCH IN ECOLOGICAL RESTORATION: THE ECOVARS PROJECT

We were involved as researchers in the Ecovars project. This project was carried out as a partnership between experts in plant conservation, experts in seed production, and researchers in genetics and social sciences. The aim of Ecovars was to promote the use of local seeds for alpine grassland restoration in the Pyrenees mountains (Fig. 1).

Context and Partnership of the Ecovars Project

The idea of using local seeds for the restoration of alpine grasslands in the Pyrenees was first developed in the 1990s to restore small areas in the Pyrenean National Park (Fig. 2). In 1998, the Pyrenean Botanical Conservatory (PBC) recommended a generalized use of local seeds throughout the Pyrenees mountain range, in particular to restore plant cover after the construction of ski resorts. The use of non-local species for restoration may (i) increase the risk of a poor adaptation leading to technical failure, and (ii) provide a threat for local plant populations: mating between local and nonlocal genotypes can reduce the fitness of local plant progenies through gene swamping or outbreeding depression [START_REF] Hufford | Plant ecotypes: genetic differentiation in the age of ecological restoration[END_REF]. The use of local seeds appeared to be a good solution to avoid these problems. However, scaling up from the Park to the Pyrenean massif increased the amount of seeds needed and required the production of seeds of native species. The objectives were threefold: (i) choose and collect pioneer species whose ranges cover the massif, (ii) clarify what "local" entails by taking into account the genetic differentiation of the targeted species along the massif, and (iii) produce the seeds. To complete these tasks, the PBC and a geneticist from the French national institute of agronomy (INRA) set up the Ecovars project (2005)(2006)(2007)(2008) (Fig. 2). This project was run by the PBC in partnership with INRA and the authority that coordinates agricultural development in the Pyrenees (SUAIA-P).

The project was organized in three work packages that corresponded to the expertise of each partner: consulting in restoration, information, and coordination (PBC), seed production (SUAIA-P), research and development (INRA) (Table 1). It was planned as a set of tasks to be accomplished by each partner (Table 1). The PBC managed the project and also provided expertise and technical support to seed users and to the French governmental authority that controls the type of seed mixture sown in restoration projects. The PBC was also responsible for communication on the project and for training seed users. The SUAIA-P was in charge of all aspects related to seed collection and production. Its task was based on the creation and management of a network of seed producers. They tested different cultural practices for native plants and applied the chosen practice for seed production. The INRA was in charge of genetic research into neutral and adaptive genetic structures of plant species to design seed transfer zones. Seed transfer zones are geographical regions within which the translocation of seeds of native species is supposed to have no detrimental effects on the restored population. The three work packages were coordinated by an "operational group" consisting of a representative of each organization (Fig. 3). Each representative informed the other partners of the progress made by its organization. The operational group met monthly. An "executive group" was in charge of reviewing the progress of the project (Fig. 3) and was composed of the operational group together with the heads of the three organizations; they met once every trimester. Finally, a "supervising group" composed of the executive group, financial sponsors, and some stakeholders met yearly (Fig. 3).

Focusing on the Relevance of Festuca eskia Seed Transfer Zones in the Ecovars Project

In 2004, INRA geneticists initiated studies that would lead to the design of seed transfer zones. They worked on a fescue, Festuca eskia, which had been chosen to be the main component (80%) of the future seed mixtures used in revegetation (Fig. 2). The choice of the native species to be produced and used in grassland revegetation was made by the PBC in 2001 (Fig. 2). The PBC chose pioneer species whose ranges cover the massif, like F. eskia. The aim of designating seed transfer zones for F. eskia was to determine zones within which seeds could be both collected for production and used in restoration with no genetic risk for the local populations. As a matter of fact, translocating seeds and plants from one place to another could alter the existing genetic differentiation between populations, swamp locally adapted genes and/or break-up co-adapted gene complexes in populations residing beside translocation sites. This is a population genetic concern applied to restoration (see review in However, the relevance of the F. eskia seed transfer zones as they were designed is questionable, firstly because these zones did not take into account unintentional selection occurring during the seed production process, and secondly because they failed to incorporate stakeholders' input.

The seed transfer zones lacked relevance because the unintentional selection that occurs during seed production was not taken into account. In 2005, the SUAIA-P initiated seed production of F. eskia and some other native species. During tests for different growing practices, the SUAIA-P experts noticed that the survival rate of F. eskia under cultivation conditions was not 100%. As a consequence, these plants were not included in the seed production process whereas surviving plants were unintentionally selected. The project manager was informed but, because this was not considered as a crucial problem for establishing the growing practices for seed production, this issue was not discussed by the operational group. Later, in 2007, the researchers noticed that the survival rate in their experimental fields as well as the seed production of F. eskia under cultivation conditions depended on the origin of the plants: some F. eskia populations had a low survival rate or produced few seeds under cultivation conditions. At that time, the researchers saw that this constituted a critical constraint in the use of seed transfer zones: a seed transfer zone, to be of practical use, must include at least one source population that can be multiplied under cultivation conditions. As this variability of response to cultivation conditions had not been discussed previously by the partners, seed transfer zones were designed without taking into account this constraint. In the end, the seed transfer zone designed for F. eskia based on the results of population genetics turned out to be of little use.

The F. eskia seed transfer zones also lacked relevance with regard to the points of view of the stakeholders. In 2005, INRA social scientists http://www.ecologyandsociety.org/vol13/iss2/art53/ initiated a study involving a large diversity of stakeholders who restore degraded areas or who use restored places in the Pyrenees (Fig. 2). The objective was to integrate parameters such as the patrimonial value or the local use of alpine plant genetic resources in the design of seed transfer zones. Stakeholders (e.g., technicians who restore ski runs, livestock farmers) were interviewed to explain their use of the area to be restored and their opinion on the use of local plant species in its restoration. To their astonishment, the scientists learned from the stakeholders that F. eskia was "weeded from the ski slopes because it doesn't hold back the snow," it "triggers avalanches because it makes the snow slide," it creates slippery canopies that are dangerous for hikers, who called it the "killer grass," and "it is left by the sheep because they bleed from the muzzle when they graze on it." Consequently, in 2007, an enforced change in alpine species was made for the rest of the Ecovars project. However, the genetic research on F. eskia that had been initiated in 2004 could not now be switched to another species in 2007 because of the heavy workload involved. The research on F. eskia was pursued, but as a fundamental population genetics study.

FINDINGS: WHAT WENT WRONG?

Despite a well-designed organizational structure for the partnership in the Ecovars project (Table 1, Figs. 2 and3), the coordination between the partners was insufficient to produce relevant knowledge with regard to the shared objectives of the project. This resulted, for example, in designing seed transfer zones without taking into account the unintentional selection that occurs during seed production. Three conditions could have facilitated the production of more relevant knowledge: q setting up a reflexive discussion forum, i.e., a debating committee where each partner can expose and discuss his point of view and practices, integrating feedback from the other partners. In the Ecovars project, there was no structure that could serve as a forum for discussing our ideas, our values, and our different work practices: when results or problems were tackled by the operational group, they were transmitted as information rather than for group discussion. As a http://www.ecologyandsociety.org/vol13/iss2/art53/ consequence, there was no co-production of knowledge by the Ecovars partners and this was a limiting factor in the relevance of the knowledge produced. Establishing a reflexive discussion forum requires a form of organization where there is less partitioning of tasks between work packages; q interfacing the work packages. Even if the work packages in the Ecovars project were complementary, the fact that the each partner's tasks were partitioned in each work package reduced interactions; q developing a "coordination" management style. The coordinator, while managing the partners and playing the role of decision maker, should also promote exchanges between partners and ensure that different points of view can be expressed for each question.

Moreover, despite collaborations with partners who know the field, the geneticists failed to produce knowledge that could be used to deal with a complex problem because the end users were not directly involved in the problem-finding process. However, the project partners found what appeared at the outset to be a clear research problem: what is the genetic differentiation of targeted species along the massif and which seed transfer zones can be used to preserve these differentiations? So, the geneticists worked in partnership with the PBC and the SUAIA-P, which were, more or less explicitly, the mouthpiece for the end users (seed users and seed producers). However, when considering the point of view of the end users on F. eskia, it became obvious that the definition of the problem was too restrictive, which led to an inappropriate initial choice of species by the PBC. If seed users, such as the technicians who restore ski runs, had been involved in the problem-finding process, they would have indicated their reluctance to sow F. eskia because it does not hold back the snow on the ski slopes. Furthermore, a discussion with stakeholders who use the restored area would also have revealed their reluctance vis-à-vis F. eskia. For example, the involvement of livestock farmers in problem finding might have given rise to a discussion on the palatability of different grass species that could be used to restore alpine areas maintained by grazing herds. The change in the chosen species in midproject could probably have been avoided if the partners in the project had held discussions with these other stakeholders early enough. The project partners could have taken into account the unavoidable constraints of the end users to identify the problem and its complexity. Thus, despite being involved in a real partnership, the project partners fell into the trap of a reductionist vision of a real, complex problem. The geneticists and experts of PBC and SUAIA-P alike, in limiting the problem to the conventional questions of academic disciplines (e.g., questions pertaining to population genetics) failed to contextualize. The consequence with regard to the research questions was that the experiments led to results that were of little practical relevance.

DISCUSSION: RE-EXAMINING PARTNERSHIPS IN RESTORATION PROJECTS Partner Diversity for a Relevant Plan of Action in Restoration Projects

It is essential to have a diversity of stakeholders involved in problem finding and problem solving to grasp the full complexity of a problem. This is also essential to enable the implementation of a relevant plan of action. In the Ecovars project, partner diversity was too restricted to allow a real contextualization, especially of the scientific knowledge, and consequently hindered the production of knowledge relevant for the field work. Several research and development actions were launched but with a poor understanding of end-user expectations and of the social acceptability of the proposed solutions. This was the case when choosing F. eskia as the main species to be produced. Our experience reinforces and gives substance to the idea that Mode-2 knowledge production should start with a dialogue among a large number of different players to identify the problems [START_REF] Nowotny | Rethinking science[END_REF]). This early phase also gives the partners the opportunity to state their values and ethical motives and build the "common world" of the project. This is particularly important in ecological restoration because every time an ecosystem is restored, a particular view of nature is expressed [START_REF] Higgs | The two-culture problem: ecological restoration and the integration of knowledge[END_REF].

Consequently, depending on who participates, the problem-finding and problem-solving processes may result in very different plans of action. The Ecovars project was initially aimed at large-scale seed production by the leading partner (PBC). This http://www.ecologyandsociety.org/vol13/iss2/art53/ choice was not then discussed by the two other partners. A more comprehensive involvement of different stakeholders could have led to the problem being posed in completely different terms. The initial problem is that the construction of ski resorts destroys the plant cover. Rethinking construction techniques, saving topsoil and plant cover, which can later be returned to the degraded area, or promoting plant colonization from neighboring regions are other alternatives that could have been explored.

In return, the type of problem determines identification of the participants invited to take part in the process. Thus, there is a recursiveness between the definition of the questions and the participants involved. The problems, and the contexts in which they emerge, are never permanently fixed. Therefore, participants have to accept a form of inadequacy in the project formulations. This variability in context and problem requires a flexible and loose organizational structure of projects that is in contrast to the strict and partitioned tasks defined in projects like Ecovars. For this reason, it is not possible to formulate precise recommendations for setting up restoration projects.

Nevertheless, general principles can be defined for setting up appropriate partnerships. However, putting them into action requires a genuine effort to contextualize each particular case (van Aken 2005).

Adopting Participatory Approaches to Partnerships that Promote Collective Learning

Developing participatory approaches is likely to promote collective processes of problem finding and problem solving, which are the core processes of Mode-2. For several years now, researchers have been setting up participatory research structures to tackle complex problems of the real world. Although participatory research has been used in the fields of agriculture and natural resource management (e.g., [START_REF] Pretty | Participatory learning for sustainable agriculture[END_REF][START_REF] Bawden | Learning to persist. A systemic view of development[END_REF], it has been a fertile ground for development in ecological restoration [START_REF] Light | The politics of ecological restoration[END_REF][START_REF] Light | Restoration, the value of participation and the risks of professionalization[END_REF][START_REF] Hagen | Communicative approaches to restoration ecology: a case study from Dovre Moutain and Svalbard, Norway[END_REF]. Although participatory approaches have in common the participation of different stakeholders, there are many interpretations of the term "participation" [START_REF] Pretty | Participatory learning for sustainable agriculture[END_REF]. Participation can be seen as a means to achieve the adoption of certain measures or orientations decided by those who are leading the project: this is manipulative participation. Conversely, selfmobilization is the extreme form of empowerment in which local actors coordinate their actions to solve a problem [START_REF] Pretty | Participatory learning for sustainable agriculture[END_REF]. Between these two extremes there is a gradient of approaches tending toward the setting up of "systems of learning and action" [START_REF] Pretty | Participatory learning for sustainable agriculture[END_REF]. Among these participatory approaches, we think that the ones focused on collective learning processes are more likely to facilitate the processes of problem finding and problem solving (e.g., [START_REF] Röling | Social learning for sustainable agriculture[END_REF], LEARN-Group 2000[START_REF] Couix | Concerted approach to land-use management: developing common working procedures. A Cevennes case study (France)[END_REF]. The strategy of the project coordinator is then to involve all stakeholders (local actors, researchers, etc.) in a collective learning situation aimed at finding and solving problems. Our experience with the Ecovars project showed that the traditional management style and project structure failed to commit the three partners to a collective process of problem finding and problem solving.

These approaches require a conception of knowledge and learning different from the dominant approach (LEARN-Group 2000, Blackmore 2007). Simply put, this conception acknowledges: q that knowledge no longer results exclusively from the academic production of researchers: all stakeholders have a knowledge production activity that may contribute to the formulation and resolution of problems. The aim of these approaches is to combine scientific and layman knowledge, or indeed to allow the coproduction of hybrid knowledge. q the situational and highly contextual character of knowledge. Knowledge, in the theoretical framework of action or situated cognition (e.g., [START_REF] Suchman | Plans and situated actions. The problem of human-machine communication[END_REF][START_REF] Cook | Bridging epistemologies: the generative dance between organizational knowledge and organizational knowing[END_REF], Orlikowsky 2002[START_REF] Gherardi | Organizational knowledge. The texture of workplace learning[END_REF], is no longer considered as something stable that is presumably contained in the mind, but as a specific production in action tied to a specific context. [START_REF] Cook | Bridging epistemologies: the generative dance between organizational knowledge and organizational knowing[END_REF], for example, propose moving from "the epistemology of possession [...] towards an epistemology of practices." Thus, knowledge is always rebuilt in action, through daily practices: "knowing is practicing" [START_REF] Gherardi | Organizational knowledge. The texture of workplace learning[END_REF].

Moving from Knowledge Transfer to Knowledge Co-Production in Restoration Projects

The above perspective on participative systems of learning and action challenges the notion of knowledge transfer. Knowledge is usually considered as something that can be transferred from scientists to practitioners provided that a good communication technique is used. However, according to many authors, knowledge is not passed down from scientists to practitioners; practitioners reconstruct knowledge in their daily activities. [START_REF] Cook | Bridging epistemologies: the generative dance between organizational knowledge and organizational knowing[END_REF] consider "knowledge as a tool of knowing" that can be mobilized in the action during which "we are seeking what we need in order to do what we want to do." Orlikowsky (2002) makes the more radical claim that no form of knowledge is transferable. At best, information or data can be transferred. According to this author, "sharing 'knowing how' can be seen as a process of enabling others to learn the practice that entails the 'knowing how'. It is a process of helping others develop the ability to enact-in a variety of contexts and conditions-the knowing in practice." Consequently, it is important to reconsider the role of researchers within participatory approaches, particularly in terms of knowledge production. It is no longer a question of knowledge transfer from the researchers to the other participants but a question of knowledge co-production. For example, the lack of relevance of the seed transfer zones designed in the Ecovars project is partly attributable to the fact that they were not co-constructed. The seed transfer zones should not have been designed "in the lab" to be applied or even adapted to the field, but directly co-designed in a process involving at the very least the other participants of the project and at best several other stakeholders. The role of researchers in participatory approaches should not only be to help find and solve technical problems but also to facilitate learning processes among the participants (LEARN-Group 2000).

In return, participatory approaches imply a real involvement of the other participants too. They should abandon the conventional and passive posture that consists of submitting a problem and waiting for a "good to go" solution. So, participatory approaches presuppose a profound transformation of the role developed by the organizations dedicated to the transfer of knowledge. The project manager, whether a researcher or not, has to become a coordinator and a facilitator, and go beyond the standard role of leader or boss, encouraging new ways of thinking about problems and collective learning. These transformations are not straightforward and may involve a real collective learning process (LEARN-Group 2000, Steyaert and[START_REF] Steyaert | The European Water Framework Directive : how ecological[END_REF].

In conclusion, we would say that, if the need for participatory approaches that promote collective and reflexive processes of problem finding and problem solving is becoming widely acknowledged in conservation and restoration projects, putting such processes into practice is not only a challenge for the researchers but also for the researchers' partners. In other words, changing the knowledge production from Mode-1 to Mode-2 [START_REF] Gibbons | The new production of knowledge: the dynamics of science and research in contemporary societies[END_REF] does not depend only on researchers who have to change their research practices but also on the other actors who should enter the participatory process. It presupposes a profound transformation of the role of each partner in such projects.

Fig. 1 .

 1 Fig. 1. Map of the Pyrenees massif showing the alpine zone area.

Fig. 2 .

 2 Fig. 2. Chronology of the events before and during the Ecovars project.

Fig. 3 .

 3 Fig. 3. Coordination of the Ecovars project.

  Ecology and Society 13(2): 53 http://www.ecologyandsociety.org/vol13/iss2/art53/

Table 1 .

 1 Organization of the Ecovars project in three work packages

	Organization	Description	Skills	Work package in	Tasks
	Abbreviation			Ecovars
	PBC	Pyrenean botanical	Experts in plant	Expertise, information,	Leadership of the
		conservatory	conservation	and coordination	Ecovars project
					Technical expertise for
					the restoration of
					degraded alpine sites
					Information and
					communication on the
					Ecovars project
					Stakeholders network
					management ( from
					seed prescribers to seed
					users)
	SUAIA-P	Authority that	Experts in seed	Seed production	Seed collection of local
		coordinates agricultural	production		species at high altitude
		development in the
		Pyrenees			Development of
					methods for the seed
					production of local
					species
					Development of a
					network of seed
					production farmers
	INRA	French institute of	Genetic and social	Research and	Determination of the
		agronomical research	science researchers	development	genetic structure of
					local plant populations
					Study of factors that
					could influence
					population structure
					Coordination for the
					design of consensual
					seed transfer zones
					Examination of the
					partnership

INRA, UMR 1248 AGIR, ORPHEE: Outils et références pour la gestion des systèmes herbagers,

INRA, UMR 1248 AGIR, MEDIATIONS: Accompagnement des activités agricoles et nouvelles ruralités