The origin and remolding of genomic islands of differentiation in the European sea bass
|Author(s)||Duranton Maud1, 2, Allal Francois2, 3, Fraisse Christelle1, 2, Bierne Nicolas1, 2, Bonhomme Francois1, 2, Gagnaire Pierre-Alexandre1, 2|
|Affiliation(s)||1 : EPHE, Inst Sci Evolut Montpellier, UM UMR5554, CNRS,IRD, Pl Eugene Bataillon, F-34095 Montpellier, France.
2 : Univ Montpellier, Pl Eugene Bataillon, F-34095 Montpellier, France.
3 : Univ Montpellier, MARBEC, IFREMER, CNRS,IRD,UM, F-34250 Palavas Les Flots, France.
|Source||Nature Communications (2041-1723) (Nature Publishing Group), 2018-06 , Vol. 9 , N. 1 , P. 2518 (11p.)|
|WOS© Times Cited||70|
Speciation is a complex process that leads to the progressive establishment of reproductive isolation barriers between diverging populations. Genome-wide comparisons between closely related species have revealed the existence of heterogeneous divergence patterns, dominated by genomic islands of increased divergence supposed to contain reproductive isolation loci. However, this divergence landscape only provides a static picture of the dynamic process of speciation, during which confounding mechanisms unrelated to speciation can interfere. Here we use haplotype-resolved whole-genome sequences to identify the mechanisms responsible for the formation of genomic islands between Atlantic and Mediterranean sea bass lineages. Local ancestry patterns show that genomic islands first emerged in allopatry through linked selection acting on a heterogeneous recombination landscape. Then, upon secondary contact, preexisting islands were strongly remolded by differential introgression, revealing variable fitness effects among regions involved in reproductive isolation. Interestingly, we find that divergent regions containing ancient polymorphisms conferred the strongest resistance to introgression.