Using neutral, selected, and hitchhiker loci to assess connectivity of marine populations in the genomic era

Pierre-Alexandre Gagnaire (1, 2) , Thomas Broquet (3) , D. Aurelle (4) , Frédérique Viard (3) , Ahmed Souissi (1) , François Bonhomme (1, 2) , Sophie Arnaud-Haond (1, 5) , Nicolas Bierne (1, 2)

1 UM - Université de Montpellier
2 UMR ISEM - Institut des Sciences de l'Evolution de Montpellier
3 DIVCO - DIVersité et COnnectivité dans le paysage marin côtier
4 IMBE - Institut méditerranéen de biodiversité et d'écologie marine et continentale
5 UMR MARBEC - MARine Biodiversity Exploitation and Conservation

Estimating the rate of exchange of individuals among populations is a central concern to evolutionary ecology and its applications to conservation and management. For instance, the efficiency of protected areas in sustaining locally endangered populations and ecosystems depends on reserve network connectiv-ity. The population genetics theory offers a powerful framework for estimating dispersal distances and migration rates from molecular data. In the marine realm, however, decades of molecular studies have met limited success in inferring genetic connectivity, due to the frequent lack of spatial genetic structure in species exhibiting high fecundity and dispersal capabilities. This is especially true within biogeographic regions bounded by well-known hotspots of genetic differentiation. Here, we provide an overview of the current methods for estimating genetic connectivity using molecular markers and propose several directions for improving existing approaches using large population genomic datasets. We highlight several issues that limit the effectiveness of methods based on neutral markers when there is virtually no genetic differentiation among samples. We then focus on alternative methods based on markers influenced by selection. Although some of these methodologies are still underexplored, our aim was to stimulate new research to test how broadly they are applicable to nonmodel marine species. We argue that the increased ability to apply the concepts of cline analyses will improve dispersal inferences across physical and ecological barriers that reduce connectivity locally. We finally present how neutral markers hitchhik-ing with selected loci can also provide information about connectivity patterns within apparently well-mixed biogeographic regions. We contend that one of the most promising applications of population genomics is the use of outlier loci to delineate relevant conservation units and related eco-geographic features across which connectivity can be measured.

Mots clés: population genomics; gene flow; marine conservation; connectivity; population structure

Domaines: Génomique, Transcriptomique et Protéomique [q-bio.GN]; Biologie du développement; Ecosystèmes

Pierre-Alexandre Gagnaire, Thomas Broquet, D. Aurelle, Frédérique Viard, Ahmed Souissi, et al.. Using neutral, selected, and hitchhiker loci to assess connectivity of marine populations in the genomic era. Evolutionary Applications, 2015, 8 (8), pp.769-786. ⟨10.1111/eva.12288⟩. ⟨hal-01187735⟩