RT Journal Article
SR Electronic
T1 Parallel use of a shared genomic island of speciation in clinal and mosaic hybrid zones between cryptic seahorse lineages
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 161786
DO 10.1101/161786
A1 Florentine Riquet
A1 Cathy Liautard-Haag
A1 Lucy Woodall
A1 Carmen Bouza
A1 Patrick Louisy
A1 Bojan Hamer
A1 Francisco Otero-Ferrer
A1 Philippe Aublanc
A1 Vickie Béduneau
A1 Olivier Briard
A1 Tahani El Ayari
A1 Sandra Hochscheid
A1 Khalid Belkhir
A1 Sophie Arnaud-Haond
A1 Pierre-Alexandre Gagnaire
A1 Nicolas Bierne
YR 2017
UL http://biorxiv.org/content/early/2017/07/10/161786.abstract
AB Diverging semi-isolated lineages either meet in narrow clinal hybrid zones, or have a mosaic distribution associated with environmental variation. Intrinsic reproductive isolation is often emphasized in the former and local adaptation in the latter, although both can contribute to isolation. Rarely these two patterns of spatial distribution are reported in the same study system, while this could provide fundamental information on the endless debate about the relative contribution of intrinsic reproductive isolation and local adaptation on the speciation process. Here we report that the low diversity long-snouted seahorse Hippocampus guttulatus is genetically subdivided into five cryptic semi-isolated lineages. Along the Atlantic coasts, northern and southern lineages meet and coexist with little hybridization in the southwest of France, forming a clinal hybrid zone. In the Mediterranean Sea, two lineages have a mosaic distribution associated with lagoon-like and marine habitats. A fifth lineage was identified in the Black Sea. Genetic homogeneity over large spatial scales within each lineage, together with among-locus variance in differentiation levels between lineages and spatial patterns of introgression provide evidence that partial reproductive isolation is maintaining the divergence. Surprisingly, the North Atlantic and the Mediterranean lagoon lineages are genetically similar for a single chromosome-wide island showing parallel genetic differentiation among regions. Since Atlantic lineages distribution lacks association with habitat variation, genetic parallelism suggests that a shared genomic barrier contributes to reproductive isolation in contrasted contexts -i.e. spatial vs. ecological. We discuss how a genomic hotspot of parallel differentiation could have evolved and become associated either with space or with a patchy environment in a single study system.