Allelic Richness Values Research Articles

Genetic traces of dispersal and admixture in red deer (Cervus elaphus) populations from the Carpathian Basin

After the last glacial, the Carpathian Basin was repopulated from either eastward or northward colonisation routes for various species; one of these was the emblematic member of the European megafauna, the red deer, Cervus elaphus. We analysed 303 red deer individuals from the middle of the region, in seven Hungarian game reserves, at ten microsatellite loci (C01, C229, T26, T108, T123, T156, T172, T193, T501, T507), to investigate the genetic diversity of these subpopulations. We discovered high levels of genetic diversity of red deer subpopulations; allelic richness values ranging 4.99–7.01, observed heterozygosity 0.729–0.800, polymorphic information content 0.722–0.806, and Shannon’s information index 1.668–2.064. Multi-locus analyses indicated population admixtures of various degrees that corresponded to geographical location, and complex genetic structures were shown by clustering. Populations in the south-western and the north-eastern parts of the region formed two highly separated groups, and the red deer from populations in between them were highly admixed (in western Pannonia/Transdanubia, where the Danube flows into the Carpathian Basin). This pattern corresponds to the distribution of mitochondrial as well as Y-chromosome lineages. Assignment tests showed that a large fraction of individuals (29.4%) are found outside of their population of origin, indicating that the dispersal of red deer is rather common, which could be expected considering the life course of the species.

Does the genetic diversity among pubescent white oaks in southern Italy, Sicily and Sardinia islands support the current taxonomic classification?

Molecular diversity analysis of deciduous pubescent oaks was conducted for populations from Calabria, Sicily and Sardinia. The aims of this study were twofold. First, to provide data on the genetic diversity of pubescent oaks from an understudied area which currently exhibits one of the highest concentrations of pubescent oak species in Europe. Second, to verify if these groups of oaks are genetically distinct and if their identification is in accordance with the current taxonomic classification. Molecular analyses of leaf material of 480 trees from seventeen populations belonging to putatively different pubescent oak species (Quercus amplifolia, Q. congesta, Q. dalechampii, Q. ichnusae, Q. leptobalanos, Q. virgiliana) were performed. Twelve gene-based Expressed Sequence Tag-Simple Sequence Repeat markers were selected, and genetic diversity and differentiation were calculated. The results showed relatively high values of allelic richness, heterozygosity and number of private alleles for the populations investigated. A weak but positive correlation between geographical and genetic distance was detected. Genetic assignment (STRUCTURE) and principle coordinate analyses exhibited a weak separation into two genetic groups which, however, did not correspond to the taxonomic, chorological and ecological features of the populations investigated. Sardinian populations formed one group which was separated from the Calabrian and Sicilian populations. In light of the results obtained, the taxonomic classification for the pubescent white oaks currently reported in the major Italian floras and checklists for the study area was not confirmed by molecular analyses.

Genetic Diversity of Historical and Modern Populations of Russian Cattle Breeds Revealed by Microsatellite Analysis.

Analysis of ancient and historical DNA has great potential to trace the genetic diversity of local cattle populations during their centuries-long development. Forty-nine specimens representing five cattle breeds (Kholmogor, Yaroslavl, Great Russian, Novgorod, and Holland), dated from the end of the 19th century to the first half of the 20th century, were genotyped for nine polymorphic microsatellite loci. Using a multiple-tube approach, we determined the consensus genotypes of all samples/loci analysed. Amplification errors, including allelic drop-out (ADO) and false alleles (FA), occurred with an average frequency of 2.35% and 0.79%, respectively. A significant effect of allelic length on ADO rate (r2 = 0.620, p = 0.05) was shown. We did not observe significant differences in genetic diversity among historical samples and modern representatives of Kholmogor and Yaroslavl breeds. The unbiased expected heterozygosity values were 0.726–0.774 and 0.708–0.739; the allelic richness values were 2.716–2.893 and 2.661–2.758 for the historical and modern samples, respectively. Analyses of FST and Jost’s D genetic distances, and the results of STRUCTURE clustering, showed the maintenance of a part of historical components in the modern populations of Kholmogor and Yaroslavl cattle. Our study contributes to the conservation of biodiversity in the local Russian genetic resources of cattle.

Genetic Variability of Dolly Varden (Salvelinus malma), White-Spotted Char (S. leucomaenis), and Interspecific Hybrids from the Utkholok River (Northwestern Kamchatka)

The genetic variability of Dolly Varden, white-spotted char, and their interspecific hybrids for nine nuclear DNA microsatellite loci and the mtDNA CO1 gene was investigated. Significant genetic divergence between the two species of char for all microsatellite loci was shown (FST = 0.529; p < 0.001). Dolly Varden was characterized by significantly greater genetic variability compared to white-spotted char in terms of the average expected heterozygosity (HE) and allelic richness (AR). Hybrids had intermediate HE and AR values compared to their parents. Three haplotypes in the CO1 gene were revealed. All phenotypic white-spotted char individuals and the hybrids had one haplotype that was specific to S. leucomaenis. Specimens that were phenotypically identified as Dolly Varden had two haplotypes related to S. malma. Thus, the hybrids were produced by males of Dolly Varden and females of white-spotted char. The individuals with hybrid genotypes, except for one, were the first generation hybrids (F1). One char may be a descendant of a hybrid crossbreeding with one of the parental species or a second-generation hybrid F2, indicating that hybridization between the species studied is introgressive.

Comprehensive assessment of the genetic diversity and population structure of cultured populations of golden pompano, Trachinotus ovatus (Linnaeus, 1758), by microsatellites

Golden pompano, Trachinotus ovatus, belongs to the family Carangidae. Within one decade, this species has rapidly become one of the most important cultured marine fish species in South China. However, the lack of a comprehensive genetic diversity assessment hinders the conservation of natural resources and management of cultured populations. Thus, we sampled one wild population and six cultured populations of golden pompano, which represented the whole cultured population, to assess the genetic diversity and population structure. The level of genetic diversity was low compared with those of other cultured fish, as the values of allelic richness, number of effective alleles and expected heterozygosity in the combined whole sample were 3.709, 2.592, and 0.591, respectively. These populations were little differentiated (Fst = 0.02091, p value = 0.00), and the whole sample did not show an explicit population structure at the individual level. The effective population size in each cultured population was small and in the whole sample was acceptable for a closed selection system. The pedigree reconstruction showed no evidence of artificial disturbance in mating. This general survey of cultured golden pompano populations showed the common characteristics of domestication with wild inputs. However, the low level of and potential decrease in genetic diversity should receive close attention in future breeding programs. In addition, we recommend wide surveys of natural resources and the establishment of closed breeding systems to increase genetic gain.

Climate change refugia and habitat connectivity promote species persistence

BackgroundClimate change refugia, areas buffered from climate change relative to their surroundings, are of increasing interest as natural resource managers seek to prioritize climate adaptation actions. However, evidence that refugia buffer the effects of anthropogenic climate change is largely missing.MethodsFocusing on the climate-sensitive Belding’s ground squirrel (Urocitellus beldingi), we predicted that highly connected Sierra Nevada meadows that had warmed less or shown less precipitation change over the last century would have greater population persistence, as measured by short-term occupancy, fewer extirpations over the twentieth century, and long-term persistence measured through genetic diversity.ResultsAcross California, U. beldingi were more likely to persist over the last century in meadows with high connectivity that were defined as refugial based on a suite of temperature and precipitation factors. In Yosemite National Park, highly connected refugial meadows were more likely to be occupied by U. beldingi. More broadly, populations inhabiting Sierra Nevada meadows with colder mean winter temperatures had higher values of allelic richness at microsatellite loci, consistent with higher population persistence in temperature-buffered sites. Furthermore, both allelic richness and gene flow were higher in meadows that had higher landscape connectivity, indicating the importance of metapopulation processes. Conversely, anthropogenic refugia, sites where populations appeared to persist due to food or water supplementation, had lower connectivity, genetic diversity, and gene flow, and thus might act as ecological traps. This study provides evidence that validates the climate change refugia concept in a contemporary context and illustrates how to integrate field observations and genetic analyses to test the effectiveness of climate change refugia and connectivity.ConclusionsClimate change refugia will be important for conserving populations as well as genetic diversity and evolutionary potential. Our study shows that in-depth modeling paired with rigorous fieldwork can identify functioning climate change refugia for conservation.

Microsatellite variation in Donax trunculus from the Iberian Peninsula, with particular attention to Galician estuaries (NW Spain)

Genetic variation and population structure information is essential for conservation and stock management policies. The wedge clam Donax trunculus is an important fishing resource in the Iberian Peninsula and in some areas, such as the northwestern Spain, wild stocks have decreased greatly. Despite this, information is mainly from the southwestern Atlantic to the northwestern Mediterranean of the Iberian Peninsula. In this study, fifteen microsatellite loci were examined at 17 localities along the Iberian Peninsula to characterize its genetic diversity and population structure. Particular attention was paid to the northwestern Atlantic area, and to test if the pattern previously described for this species is confirmed when localities distributed across the Atlantic coast are included and different microsatellite markers are used. All localities displayed similar allelic richness values and heterozygosity levels but when genetic diversity levels were compared among groups of localities, tests were significant and samples from the northwestern area (Galicia) showed the lowest values. The analysis of population structure indicated that localities from the Atlantic coast are genetically homogeneous although some samples showed significant pairwise Fst values. These values were low and Bayesian analysis of genetic differentiation did not show a consistent structure along the Atlantic coast of the Iberian Peninsula. However, Atlantic samples were genetically different from those located in Mediterranean coast, which may be explained by the existence of the Almeria-Oran front. Moreover, Fuengirola, locality situated in the Alboran Sea between the Strait of Gibraltar and Mediterranean Sea, showed significant differences from all remaining localities included in the study. Overall, the data showed the existence of genetic homogeneity along the Atlantic coast of the Iberian Peninsula and support the three management units (Atlantic Ocean, the Alboran Sea and the northwestern Mediterranean) previously described in this species. Reduced diversity in the northwestern Spain samples could be related to the exploitation of this resource.

Local-Level Genetic Diversity and Structure of Matsutake Mushroom (Tricholoma matsutake) Populations in Nagano Prefecture, Japan, Revealed by 15 Microsatellite Markers

The annual yield of matsutake mushrooms (Tricholoma matsutake) has consistently decreased in Japan over the past few decades. We used 15 polymorphic and codominant simple sequence repeat (SSR) markers, developed using next-generation sequencing, to carry out genetic analyses of 10 populations in Nagano, Japan. Using the SSRs, we identified 223 genotypes, none of which was observed in more than one population. The mean expected heterozygosity and standardized allelic richness values were 0.67 and 4.05, respectively. Many alleles appeared in only one of the 10 populations; 34 of these private alleles were detected with a mean number per population of 3.4. The fixation index (FST) and standardized genetic differentiation (G′ST) values were 0.019 and 0.028, respectively. Analysis of molecular variance (AMOVA) showed that the contribution of among population, among genets within a population, and within genets variation to the total variation was 2.91%, 11.62%, and 85.47%, respectively, with genetic differentiation being detected for all sources. Twenty-eight of 45 pairwise FST values were significantly larger than zero, and no pattern of isolation by distance was detected among the 10 populations. Bayesian-based clustering did not show clear differences among populations. These results suggest that reestablishment of a colony would be best accomplished by transplantation within a field; if this is not possible, then transplantation from within several dozen kilometers will cause little damage to the original population genetic structure.

Substantial functional diversity accompanies limited major histocompatibility complex class II variability in golden jackal (Canis aureus): A comparison between two wild Canis species in Croatia

The golden jackal (Canis aureus) is one of the less studied carnivores and research on its major histocompatibility complex (MHC) variability is just at its early stages. MHC genes encode cell-surface receptors that serve to bind and present antigens to T cells, which is essential to initiating specific immunological responses in vertebrates. In this paper we present for the first time patterns of genetic diversity and natural selection on MHC class II DLA-DRB1, DQA1 and DQB1 loci in the golden jackal using samples from two geographically distinct regions in Croatia and further compare them to the values found in its congener grey wolf (Canis lupus). Diversity of golden jackals at all three loci was markedly lower than that of grey wolves (allelic richness values were 4, 2 and 3 in jackal versus 11.9, 6.6 and 10.2 in wolves for DRB1, DQA1 and DQB1, respectively) and can be attributed to a genetic drift rather than to the lack of historical positive selection. The finding of high evolutionary distances (16.3% for DRB1 and 8.5% for DQB1) and a substantial number of codons predicted to be under the influence of positive selection (11 for DRB1 and 9 for DQB1) suggests that the investigated golden jackal population still contains considerable functional diversity necessary for the presentation of varied foreign peptides. In contrast to neutral genetic variation, our results suggest that the Dalmatian population has a higher MHC diversity than the Slavonian population, casting doubt on its supposed isolation and calling for a more extensive investigation of the MHC variability of southern Balkan jackal populations.

Effect of sampling methods, effective population size and migration rate estimation in Glossina palpalis palpalis from Cameroon

Human and animal trypanosomiases are two major constraints to development in Africa. These diseases are mainly transmitted by tsetse flies in particular by Glossina palpalis palpalis in Western and Central Africa. To set up an effective vector control campaign, prior population genetics studies have proved useful. Previous studies on population genetics of G. p. palpalis using microsatellite loci showed high heterozygote deficits, as compared to Hardy–Weinberg expectations, mainly explained by the presence of null alleles and/or the mixing of individuals belonging to several reproductive units (Wahlund effect). In this study we implemented a system of trapping, consisting of a central trap and two to four satellite traps around the central one to evaluate a possible role of the Wahlund effect in tsetse flies from three Cameroon human and animal African trypanosomiases foci (Campo, Bipindi and Fontem). We also estimated effective population sizes and dispersal. No difference was observed between the values of allelic richness, genetic diversity and Wright’s FIS, in the samples from central and from satellite traps, suggesting an absence of Wahlund effect. Partitioning of the samples with Bayesian methods showed numerous clusters of 2–3 individuals as expected from a population at demographic equilibrium with two expected offspring per reproducing female. As previously shown, null alleles appeared as the most probable factor inducing these heterozygote deficits in these populations. Effective population sizes varied from 80 to 450 individuals while immigration rates were between 0.05 and 0.43, showing substantial genetic exchanges between different villages within a focus. These results suggest that the “suppression” with establishment of physical barriers may be the best strategy for a vector control campaign in this forest context.

Genetic characteristics of three Baltic Zostera marina populations

We performed genetic analyses of three Baltic eelgrass (Zostera marina) populations in Puck Bay (PB), Cudema Bay (CB) and Greifswalder Bodden (GB). The aim of this study was to identify the eelgrass population genetically closest to that from the PB, which could potentially serve as a reservoir for the restoration of the underwater meadows in this bay, seriously degraded in the past. We applied a 12-microsatellite assay to test the genetic distance between the target eelgrass populations. We found that the allelic richness values of the GB, PB and CB populations were 2.25, 3.77 and 3.50 respectively. The genetic diversity found in GB was low and could be explained by the population’s history, whereas the diversity of CB was higher than expected in a population located at the edge of the species’ range. Analyses of genetic differentiation and structure showed that of the three populations studied, PB and CB were closer to each other than to the GB population. The reasons for this differentiation in eelgrass populations and the implications of the results of their genetic analysis on the planned restoration of the PB populations are discussed.

Genetic characteristics of three Baltic Zostera marina populations

Abstract We performed genetic analyses of three Baltic eelgrass (Zostera marina) populations in Puck Bay (PB), Cudema Bay (CB) and Greifswalder Bodden (GB). The aim of this study was to identify the eelgrass population genetically closest to that from the PB, which could potentially serve as a reservoir for the restoration of the underwater meadows in this bay, seriously degraded in the past. We applied a 12-microsatellite assay to test the genetic distance between the target eelgrass populations. We found that the allelic richness values of the GB, PB and CB populations were 2.25, 3.77 and 3.50 respectively. The genetic diversity found in GB was low and could be explained by the population’s history, whereas the diversity of CB was higher than expected in a population located at the edge of the species’ range. Analyses of genetic differentiation and structure showed that of the three populations studied, PB and CB were closer to each other than to the GB population. The reasons for this differentiation in eelgrass populations and the implications of the results of their genetic analysis on the planned restoration of the PB populations are discussed.

Genetic structure and variability of the working dog inferred from microsatellite marker analysis

Working dogs serve as military watch dogs, search dogs, rescue dogs, and guide dogs with un-come-at-able character. They are drafted by in-training examination including concentration, capacity for locomotion, boldness and earthly desires. In this study, genetic diversity and relationships among two groups of working dogs (pass and fail group in-training examination) were assessed based on 15 microsatellite markers in 25 individuals of working dogs (military watch dogs and Korean search dogs). For the 15 microsatellite markers, the values of allelic richness (A R ) ranged from 2.21 (pass group) to 1.60 (fail group) in military watch dogs, while A R ranged from 2.79 (pass group) to 2.72 (fail group) in Korean search dogs. Among 52 different alleles of military watch dogs, 22 alleles were detected in pass group only, while 8 alleles in fail group only. In case of Korean search dogs, 3 alleles were observed in pass group only, while 13 alleles in fail group only. These group-specific unique alleles reflect good biomarker for selecting working dogs (military watch dogs and Korean search dogs), indicating that those group specific microsatellite alleles could separate working dogs to be pass or fail group in out-training dog population. Taken together, this study demonstrates the feasibility of microsatellite analyses for the selection of superior working dogs objectively. Furthermore, this approach could be used for the proper selection of working dogs in combination with in-training examination.

Management of Nothofagus genetic resources: Definition of genetic zones based on a combination of nuclear and chloroplast marker data

Development of appropriate forest conservation and management measures for a given tree species includes the identification of distinct genetically homogeneous units across its overall distribution range, which depends on the availability of knowledge on genetic, morphological and adaptive variation. This has important implications for germplasm transfer within and between areas, for example in reforestation or restoration activities. Genetic zones are defined as genetically more or less homogeneous regions within which propagation material can be transferred with relative certainty not to cause changes at the genetic structure level. The main goal of this study was to define genetic zones for Nothofagus nervosa and Nothofagus obliqua within their Argentinean natural distribution range. A total of 823 individuals belonging to 24 populations (14 of N. nervosa and 10 of N. obliqua, μ=34±5) were genotyped by means of seven nuclear microsatellite markers. The geographic clustering encountered through the application of a Bayesian approach was analyzed in combination with additional information on diversity parameters, chloroplast DNA and isozymes. For assembling the maps showing the distribution of clusters, we averaged cluster membership values of trees in each grid cell. To visualize geographical patterns in nSRR richness and the distribution of different clusters of both species, we carried out grid-based spatial analyses using 30s grid cells (∼1km at the equator) as the unit of analyses. We distinguished five genetic zones for N. nervosa and three for N. obliqua, consistent with the management history of the species, and displaying a certain level of geographic congruence. Higher allelic richness values were found in the surroundings of areas identified as potential glacial refugia, which suggest that the distribution pattern of allelic richness is closely associated with the glacial history of the species within the region. We expect this information to constitute a valuable tool for the identification of seed transfer zones, and to guide recruitment and plantation activities in the context of domestication programs of both species in Argentina. For assisted migration programs under progressive climate change the identification of these zones together with knowledge concerning hotspots at genetic diversity level should constitute an input for planning the activities.

Genetic Variation within and among Remnant Big Bluestem (Andropogon gerardii, Poaceae) Populations in the Carolinas

Genetic diversity within and among nine Andropogon gerardii (Big Bluestem) populations from various physiographic regions of North and South Carolina was assessed. Genetic diversity was high at both the species level and at the population level. At the species level, percent polymorphic loci (P) was 96.4% (27 of 28 loci), the number of alleles per polymorphic locus (AP) was 4.07, and genetic diversity (He) was 0.425. Mean within population values were P= 82.6%, AP = 2.68, and He = 0.351. Within population genetic diversity (He) ranged from 0.190 to 0.466. Allelic richness values per population ranged from 37 to 71. The proportion of genetic diversity among populations (Gst) was 0.166. Mean genetic diversity for the 3 larger populations (He = 0.369) and within the 6 smaller populations (He = 0.341) did not differ significantly (P = 0.554). Nei's unbiased genetic identity between pairs of populations ranged from 0.652 to 0.975. Mean genetic identity of individual populations with the 8 other populations ranged from 0.71 to 0.89. A Mantel test showed no significant genetic isolation by geographic distance (r = 0.065; P = 0.614). While banding patterns for most of the loci were consistent with disomic inheritance, two loci (PGI3; UGPP1) displayed patterns consistent with tetrasomic inheritance. Results of this study suggest that Big Bluestem populations in the Carolinas were once more widespread.

Genetic characterization of the indigenous Landim and Pafuri goat breeds from Mozambique.

This paper describes genetic diversity between and within the indigenous Landim and Pafuri goat breeds from Mozambique, with reference to the unimproved South African Boer goat, the paternal ancestor of the Pafuri breed. Microsatellite polymorphism was used to quantify genetic diversity and drift. Heterozygosity (Hz) in three populations of the Landim breed were closely comparable (Hz = 0.588 - 0.623), with a higher Hz value of 0.672 in Pafuri, the latter most likely reflecting the influence of the Boer goat. Allelic richness values supported this trend. Drift among individual Landim populations was low (Fst = 0.046-0.059) compared to Fst = 0.077-0.091 between the Pafuri breed and individual Landim populations, again reflecting introgression of Boer goat genetic material. The Landim populations also clustered together in a consensus neighbour-joining tree, with the Pafuri breed slightly distant and the Boer goat most distant from the Landim breed. A Bayesian assignment test placed the majority of Pafuri and Boer goat animals in a common cluster, with the Landim individuals spread over three additional clusters. The results are discussed with reference to the importance of conserving local breeds and the influence of marker sample size on statistical analysis.

A simple method for estimating genetic diversity in large populations from finite sample sizes

BackgroundSample size is one of the critical factors affecting the accuracy of the estimation of population genetic diversity parameters. Small sample sizes often lead to significant errors in determining the allelic richness, which is one of the most important and commonly used estimators of genetic diversity in populations. Correct estimation of allelic richness in natural populations is challenging since they often do not conform to model assumptions. Here, we introduce a simple and robust approach to estimate the genetic diversity in large natural populations based on the empirical data for finite sample sizes.ResultsWe developed a non-linear regression model to infer genetic diversity estimates in large natural populations from finite sample sizes. The allelic richness values predicted by our model were in good agreement with those observed in the simulated data sets and the true allelic richness observed in the source populations. The model has been validated using simulated population genetic data sets with different evolutionary scenarios implied in the simulated populations, as well as large microsatellite and allozyme experimental data sets for four conifer species with contrasting patterns of inherent genetic diversity and mating systems. Our model was a better predictor for allelic richness in natural populations than the widely-used Ewens sampling formula, coalescent approach, and rarefaction algorithm.ConclusionsOur regression model was capable of accurately estimating allelic richness in natural populations regardless of the species and marker system. This regression modeling approach is free from assumptions and can be widely used for population genetic and conservation applications.

Genetic Characterization of Russian Honey Bee Stock Selected for Improved Resistance to &lt;I&gt;Varroa destructor&lt;/I&gt;

Maintenance of genetic diversity among breeding lines is important in selective breeding and stock management. The Russian Honey Bee Breeding Program has strived to maintain high levels of heterozygosity among its breeding lines since its inception in 1997. After numerous rounds of selection for resistance to tracheal and varroa mites and improved honey production, 18 lines were selected as the core of the program. These lines were grouped into three breeding blocks that were crossbred to improve overall heterozygosity levels of the population. Microsatellite DNA data demonstrated that the program has been successful. Heterozygosity and allelic richness values are high and there are no indications of inbreeding among the three blocks. There were significant levels of genetic structure measured among the three blocks. Block C was genetically distinct from both blocks A and B (F(ST) = 0.0238), whereas blocks A and B did not differ from each other (F(ST) = 0.0074). The same pattern was seen for genic (based on numbers of alleles) differentiation. Genetic distance, as measured by chord distance, indicates that all of the 18 lines are equally distant, with minimal clustering. The data indicate that the overall design of the breeding program has been successful in maintaining high levels of diversity and avoiding problems associated with inbreeding.

An integrated comparison of captive-bred and wild Atlantic salmon ( Salmo salar): Implications for supportive breeding programs

Supportive breeding is a strategy consisting in maintaining a pool of locally-adapted wild genitors in captivity whose offspring are released in the wild at an early developmental stage. In this study, we tested the utility of this strategy in preventing phenotypic and genetic divergences between captive-bred and wild animals that could be detrimental for wild populations. Combining microsatellite analyses, morphological measurements and behavioural trials in the laboratory, we compared the progeny of Atlantic salmon ( Salmo salar) born in captivity with individuals born in the wild. At all these levels, we found significant differences between the progeny of the two groups. Specifically, allelic frequencies significantly differed between groups, with captive-bred fish tending to be less variable with lower heterozygosity and allelic richness values. The shape of wild-born fish was also different from that of the captive-group, particularly in the depth of the head and the length of the pectoral fins. Finally, captive-bred individuals were, on average, more aggressive than wild-born fish. We demonstrated that this difference was strongly dependent upon the environment as captive-bred fish were more aggressive only when together with their wild conspecifics or with an exotic competitor, the rainbow trout ( Oncorhynchus mykiss). Overall, our results showed that both phenotypic and genetic changes can arise even if genitors share a common brood-stock and after only a few months of rearing in a controlled environment. We conclude that the progeny produced in such supportive breeding programs does not meet the criteria necessary to ensure preserving the genetic and ecological integrity of wild populations.

Genetic structure and dynamics of a small introduced population: the pikeperch, Sander lucioperca, in the Rhône delta

Genetic data on introduced populations may help us to understand how these species succeed in colonising new territories. The pikeperch is a predatory fish widely introduced in Europe and has at times been considered as an invasive species. However, little is known about the genetics of both native and introduced populations. In the present study, we surveyed an introduced pikeperch population from the Rhône River delta, a habitat that has been highly modified for agricultural purposes. Using six microsatellites, we genotyped 93 individuals distributed among four hydraulically connected water bodies: the Rhône River, an irrigation canal, a drainage canal and a brackish lagoon. Population isolation were revealed by significant genetic distances and bottleneck highlighted by population monitoring. However, values of allelic richness and unbiased expected heterozygosity observed in these populations were similar, or even higher, compare to 18 native populations from the Baltic Sea drainage. It may be explained by multiple introductions in the Rhône drainage but also by demographic strategy that would have facilitated population persistence in this fragmented habitat. Similarly, heterozygote deficits (revealed by F(IS) values) have been detected, but were also found in native populations suggesting that mating among relatives could also result from a mating behavior of the species, maybe reinforce here by the reduced carrying capacity of the artificial canals and their respective isolation. Despite harsh environmental conditions and suspected inbreeding, the pikeperch has successfully maintained viable populations in the Rhône delta. Our study suggests that one of the factors in this invasive success, apart from its ecology, could be the maintenance of a good level of genetic diversity in introduced pikeperch populations. This genetic diversity probably stem from both its popularity as game fish and food resource which led to numerous stocking and an increasing propagule pressure and the reproductive strategy of the species.