Meeting Abstract
Seascape genomics evaluates the relationship between oceanographic variables and genetic structure within species through environmental association of genetic markers. We used SNPs scattered through the genome in the tunicate Pyura chilensis, a benthic species endemic of the SE Pacific coast, to infer neutral and adaptive spatial genetic structure of six local populations between 24º and 42ºS. Neutral structure was consistent with previously detected divergence with COI sequences at the 39ºS site. The remaining sites showed low genetic differentiation in spite of the low capacity of larval dispersal of P. chilensis, consistent with anthropogenic mediated dispersal in boat hulls. Adaptive SNP loci showed a different main signal that consisted on a genetic discontinuity between the sites at 29ºS and 36ºS. In that area, at 30ºS, there is a well-known biogeographic break, a region of high upwelling in which many species have a concordant phylogeographic break with COI (not P. chilensis). The genetic structure at ca. 30ºS in P. chilensis has only been detected with adaptive loci. We analysed the relationship between relevant oceanographic variables and the genetic structure and found that adaptive structure was significantly associated to variables related to upwelling and high productivity, most significantly with sea surface temperature. The seascape genomics approach detected a role of natural selection in structuring adaptive diversity; it was consistently associated to environmental variables that showed a discontinuity at 30°S, and suggests that upwelling shapes adaptive divergence spatially concordant with the 30°S biogeographic break. Funding: Fondecyt 1140862 & FONDAP INCAR 15110027.
