Trade-off between morphological convergence and opportunistic diet behavior in fish hybrid zone

<p>Abstract</p> <p>Background</p> <p>The invasive <it>Chondrostoma nasus nasus </it>has colonized part of the distribution area of the protected endemic species <it>Chondrostoma toxostoma toxostoma</it>. This hybrid zone is a complex system where multiple effects such as inter-species competition, bi-directional introgression, strong environmental pressure and so on are combined. Why do sympatric <it>Chondrostoma </it>fish present a unidirectional change in body shape? Is this the result of inter-species interactions and/or a response to environmental effects or the result of trade-offs? Studies focusing on the understanding of a trade-off between multiple parameters are still rare. Although this has previously been done for Cichlid species flock and for Darwin finches, where mouth or beak morphology were coupled to diet and genetic identification, no similar studies have been done for a fish hybrid zone in a river. We tested the correlation between morphology (body and mouth morphology), diet (stable carbon and nitrogen isotopes) and genomic combinations in different allopatric and sympatric populations for a global data set of 1330 specimens. To separate the species interaction effect from the environmental effect in sympatry, we distinguished two data sets: the first one was obtained from a highly regulated part of the river and the second was obtained from specimens coming from the less regulated part.</p> <p>Results</p> <p>The distribution of the hybrid combinations was different in the two part of the sympatric zone, whereas all the specimens presented similar overall changes in body shape and in mouth morphology. Sympatric specimens were also characterized by a larger diet behavior variance than reference populations, characteristic of an opportunistic diet. No correlation was established between the body shape (or mouth deformation) and the stable isotope signature.</p> <p>Conclusion</p> <p>The Durance River is an untamed Mediterranean river despite the presence of numerous dams that split the river from upstream to downstream. The sympatric effect on morphology and the large diet behavior range can be explained by a tendency toward an opportunistic behavior of the sympatric specimens. Indeed, the similar response of the two species and their hybrids implied an adaptation that could be defined as an alternative trade-off that underline the importance of epigenetics mechanisms for potential success in a novel environment.</p

Development of 55 novel polymorphic microsatellite loci for the critically endangered L. (Actinopterygii: Perciformes: Percidae) and cross-species amplification in five other percids

International audienceBy combining biotin-enrichment protocol and next generation pyrosequencing, through 454 GS-FLX Titanium technology, 55 polymorphic microsatellites loci with perfect motif were isolated from the Rhone streber (), a critically endangered European fish species. Eight multiplex PCR kits were optimised in order to genotype a total of 58 polymorphic loci, including three previously published loci. The level of genetic diversity was assessed for 68 , 30 , 33 and four individuals. Amplification success was also assessed on and using single individuals. These markers will be useful to investigate the population structure of the highly fragmented Rhone streber. They represent a powerful tool for conservation issues and evolutionary approaches of this endemic species. Moreover, part of our markers demonstrated applicability to other percid species, allowing for potential applications to fisheries and aquaculture management

Cross-species amplification of 41 microsatellites in European cyprinids: A tool for evolutionary, population genetics and hybridization studies

<p>Abstract</p> <p>Background</p> <p>Cyprinids display the most abundant and widespread species among the European freshwater Teleostei and are known to hybridize quite commonly. Nevertheless, a limited number of markers for conducting comparative differentiation, evolutionary and hybridization dynamics studies are available to date.</p> <p>Findings</p> <p>Five multiplex PCR sets were optimized in order to assay 41 cyprinid-specific polymorphic microsatellite loci (including 10 novel loci isolated from <it>Chondrostoma nasus nasus, Chondrostoma toxostoma toxostoma </it>and <it>Leuciscus leuciscus</it>) for 503 individuals (440 purebred specimens and 63 hybrids) from 15 European cyprinid species. The level of genetic diversity was assessed in <it>Alburnus alburnus, Alburnoides bipunctatus, C. genei, C. n. nasus, C. soetta, C. t. toxostoma, L. idus, L. leuciscus, Pachychilon pictum, Rutilus rutilus, Squalius cephalus </it>and <it>Telestes souffia</it>. The applicability of the markers was also tested on <it>Abramis brama, Blicca bjoerkna </it>and <it>Scardinius erythrophtalmus </it>specimens. Overall, between 24 and 37 of these markers revealed polymorphic for the investigated species and 23 markers amplified for all the 15 European cyprinid species.</p> <p>Conclusions</p> <p>The developed set of markers demonstrated its performance in discriminating European cyprinid species. Furthermore, it allowed detecting and characterizing hybrid individuals. These microsatellites will therefore be useful to perform comparative evolutionary and population genetics studies dealing with European cyprinids, what is of particular interest in conservation issues and constitutes a tool of choice to conduct hybridization studies.</p

From Late Miocene to Holocene: Processes of Differentiation within the Telestes Genus (Actinopterygii: Cyprinidae)

Investigating processes and timing of differentiation of organisms is critical in the understanding of the evolutionary mechanisms involved in microevolution, speciation, and macroevolution that generated the extant biodiversity. From this perspective, the Telestes genus is of special interest: the Telestes species have a wide distribution range across Europe (from the Danubian district to Mediterranean districts) and have not been prone to translocation. Molecular data (mtDNA: 1,232 bp including the entire Cyt b gene; nuclear genome: 11 microsatellites) were gathered from 34 populations of the Telestes genus, almost encompassing the entire geographic range. Using several phylogenetic and molecular dating methods interpreted in conjunction with paleoclimatic and geomorphologic evidence, we investigated the processes and timing of differentiation of the Telestes lineages. The observed genetic structure and diversity were largely congruent between mtDNA and microsatellites. The Messinian Salinity Crisis (Late Miocene) seems to have played a major role in the speciation processes of the genus. Focusing on T. souffia, a species occurring in the Danube and Rhone drainages, we were able to point out several specific events from the Pleistocene to the Holocene that have likely driven the differentiation and the historical demography of this taxon. This study provides support for an evolutionary history of dispersal and vicariance with unprecedented resolution for any freshwater fish in this region

L'apron du Rhône (Zingel asper), un poisson emblématique: Répartition, prospection et dynamique de la population du Verdon

International audienc

Two multiplexed sets of 21 and 18 microsatellites for Phoxinus phoxinus (L.) and Gobio gobio (L.) developed by cross-species amplification

International audienceA total of 68 cyprinid microsatellites were screened for cross-species amplification in order to develop three PCR multiplex kits for the Eurasian minnow (Phoxinus phoxinus L.) and the gudgeon (Gobio gobio L.). The multiplex kits cluster 21 and 18 microsatellites for P. phoxinus and G. gobio, respectively. All loci were evaluated using ~80 individuals sampled from three distinct populations. By multiplexing the markers, we aim to decrease genotyping costs and increase time efficiency. These two microsatellite sets represent a valuable tool for ecological, evolutionary, conservation and management issues

Le "barcoding alimentaire" (développement d'un nouvel outil d'écologie moléculaire pour les milieux d'eau douce)

Le principal objet de cette thèse a été d'étudier les régimes alimentaires des chondrostomes dans la Durance et de les comparer à d'autres populations évoluant dans des rivières non aménagées. Pour cela nous avons échantilloné des populations provenant de zones allopatriques nous permettant de définir des comportements alimentaires de référence. Afin de dissocier l'effet de l'aménagement de la rivière de l'effet sympatrie dans la zone Durance, nous avons échantilloné une seconde zone hybride considérée comme faiblement aménagée, l'Ardèche. L'acquisition d'une information fine de la nature des proies ingérées étant complexe à partir des techniques non invasives traditionnellement utilisées (isotopes stables), nous avons développé une méthode d'écologie moléculaire non invasive, basée sur la détermination de l'ADN présent dans les excréments du prédateur. Cette méthode repose sur des PCR spécifiques (réaction de polymérisation en chaîne) permettant de détecter 34 clades à hautes informations écologiques ("Clade Ecologique").. Les analyses des résultats nous ont permis de valider le "barcoding alimentaire" et ont montré que l'aménagement de la Durance affectait les populations de chondrostomes selon plusieurs modalités d'actions. Les résultats ont montré également que le Cnn était plus sensible par l'aménagement de la rivière que le Ctt. A l'issue de ce travail, nous proposons donc que le Cnn soit considéré comme une espèce sentinelle en vue des suivis de l'impact du débit régulé sur les communautés biologiques en Durance. En outre, cette thèse a permis le développement d'une méthode non invasive en écologie. Elaborée dans le but d'optimiser son accessibilité autant financière que technique tout en ayant permis de définir finement le comportement alimentaire des chondrostomes à travers plusieurs zones d'études, le barcoding alimentaire apparait comme une méthode très prometteuse en écologie des eaux douces.Hydroelectric settlement could lead to affect trophic resources availability for sh populations, mainly for benthos feeder species. Previous works demonstrated that in the Durance River (an highly man-impacted river), many morphological and ecological characteristics were moved in compare to reference station's populations for the two benthic feeders species, Chondrostoma toxosroma toxostoma (Ctt, endemic species) and Chondrostoma nasus nasus (Cnn, introduced species) and their hybrids. To better understand which environmental factors are responsible of these differences, we studied the diet behavior of the two Chondrostoma species. The main goal of this thesis was so to study the diet behavior of the two Chondrostoma species and their hybrids in the Durance River and to compare with i) the diet behavior of the species in allopatric stations, ii) the diet behavior of the species sampled in another hybrid zone (Ardeche River) which is less disturbed. This approach allowed distinguishing the effects played by the River anthropisation to the effect played by the species interactions. In the rst part of this work we used the stable isotope analysis (SIA) of carbon and nitrogen on several Chondrostoms populations. This approach was performed to determine the inter and intra populations variability of the diet behavior in different environments (allopatry/sympatry). However, the acquisition of taxonomic determination about ingested preys using the SIA method is difficult. To obtain this qualitative information we developed a non-invasive molecular methodology, based on DNA determination from feces. This method is based on clade speci c PCR allowing the detection of 34 taxa, with high ecological relevant information (called Ecological Clade). In order to highlights some suspected links between morphology and diet, we also studied the body and the lower lip morphologies of the Chondrostoms samples. The obtained results allowed to conclude that environmental conditions (regulated flow and substrate clogging) of the Durance River affected Chondrostomes through different process. For example we observed that Cnn are more sensitive to environmental conditions of Durance than Ctt. In this way, Cnn could be considered as a sentinel species to study impacts of a regulated river on freshwater community. More than the biological conclusions we obtained on the Chondrostoms complex, we demonstrated the usefulness of the non-invasive method we developed. This method, designed with the concern to reduce nancial and technical costs compared to other protocols (using cloning step or systematic sequencing of PCR products) could have lots of applications in ecology. Furthermore, because we take into account a high taxonomic ranks (family or order), allowing to describe diet behavior of Chondrostoms in different environments, the alimentary bar coding is not constrained to our studied sites. Thus, this method appears as a promising tool to study trophics interactions on freshwater environment.AIX-MARSEILLE1-BU Sci.St Charles (130552104) / SudocSudocFranceF

Approche éco-génomique de la biodiversité (phylogéographie comparée des cyprinidés européens et analyse spatio-temporelle des processus introgressifs entre deux espèces de chondrostomes)

Un peuplement n'est pas une entité figée et stable, mais une communauté en perpétuel renouvellement désormais soumis à l'action directe de l'homme. La phylogéographie permet de décrire et d'expliquer la répartition géographique des taxa. Bien que chaque espèce présente une histoire qui lui est propre, l'augmentation du nombre d'études a permis l'émergence de certains processus qui tendent à se généraliser. Nous avons pu mettre en évidence certains biais, indispensables à résoudre avant toute tentative de phylogéographie comparée. Chez les Teleostei en général et les Cyprinidae en particulier, les phénomènes d'hybridations sont fréquents. Suite à la vision géographique de la spéciation, abordée par l'approche phylogéographique, nous nous sommes intéressés aux mécanismes de la spéciation par l'étude de la zone hybride entre deux espèces de Chondrostomes. Celle-ci caractérisée par une hybridation introgressive bi-directionnelle suit le modèle des Nouveautés Evolutives (Arnold 1997), en combinant la présence de combinaisons génomiques environnement-indépendantes et environnement-dépendantes. Nous avons pu montrer l'importance de combiner les approches moléculaire et morphologique dans le décryptage des processus d'hybridation en permettant d'aborder les relations génome-environnement. Les phénomènes d'introgression conduisent à un débat encore délicat concernant le statut de protection des différentes entités participant à de tels processus. Cette approche éco-génomique réalisée tant au niveau populationnel que spécifique illustre la complexité des interactions existant entre gènes et milieuxAIX-MARSEILLE1-BU Sci.St Charles (130552104) / SudocSudocFranceF

Novelties in Hybrid Zones: Crossroads between Population Genomic and Ecological Approaches

International audienceBackground. Interspecific hybridization is widespread, occurring in a taxonomically diverse array of species. The Cyprinidae family, which displays more than 30% hybridization, is a good candidate for studies of processes underlying isolation and speciation, such as genetic exchange between previously isolated lineages. This is particularly relevant in the case of recent hybridization between an invasive species, Chondrostoma nasus nasus (from Eastern Europe), and C. toxostoma toxostoma (a threatened species endemic to southern France), in which bidirectional introgressive hybridization has been demonstrated. Methodology/Principal Findings. We studied 128 specimens from reference populations and 1495 hybrid zone specimens (two years of sampling and four stations), using five molecular markers (one mitochondrial gene, four nuclear introns), morphology (meristic and plastic characters) and life history traits (weight, size, coefficient of condition, sex, age, shoaling). We identified 65 hybrid combinations and visualized spatial and temporal changes in composition. The direction of mitochondrial introgression was density-dependent in favor of the rarer species and we demonstrate that the sexual selection hypothesis is a preponderant explanation in the asymmetry of introgression. Despite genomic evolution in the hybrid zone, convergence was observed for body shape and coefficient of condition, indicating changes in foraging behavior with respect to reference populations, reflecting strong environmental pressure. Conclusions/Significance. The complex rules of hybrid zone dynamics are established very early in the contact zone. We propose ''inheritance from the rare species'' as a new evolutionary hypothesis for animal models. The endemic species was not assimilated by the invasive species. Survival rates for this species were highest in the middle of the river (the warmest part) due to a trade-off between food availability and fecundity. The environment-independent hybrid combination may result from nuclear-mitochondrial interactions involving the Tpi1b gene or a gene linked to this gene (Chromosome 16). This genomic region is also responsible for shoaling behavior in Danio rerio and is a promising zone for studies of changes in population dynamics and advances in integrated studies of hybrid zones