Archive | 2021
Sardines at a junction: seascape genomics reveals ecological and oceanographic drivers of variation in the NW Mediterranean Sea
Abstract
By evaluating genetic variation across the entire genome, one can\naddress existing questions in a novel way while new can be asked. Such\nquestions include how different local environments influence both\nadaptive and neutral genomic variation within and among populations,\nproviding insights not only into local adaptation of natural\npopulations, but also into their responses to global change and the\nexploitation-induced evolution. Here, under a seascape genomic approach,\nddRAD genomic data were used along with environmental information to\nuncover the underlying processes (migration, selection) shaping European\nsardines (Sardina pilchardus) of the Western Mediterranean and adjacent\nAtlantic waters. This information can be relevant to the (re)definition\nof fishery stocks, and their short-term adaptive potential. We found\nthat studied sardine samples form two clusters, detected using both\nneutral and adaptive (outlier) loci suggesting that natural selection\nand local adaptation play a key role in driving genetic change among the\nAtlantic and the Mediterranean sardines. Temperature and especially the\ntrend in the number of days with sea surface temperature (SST) above\n19oC was crucial at all levels of population structuring with\nimplications on species’ key biological processes, especially\nreproduction. Our findings provide evidence for a dynamic equilibrium\nwhere population structure is maintained by physical and biological\nfactors under the opposing influences of migration and selection. Given\nits dynamic nature, such a system postulates a continuous monitoring\nunder a seascape genomic approach that can benefit by incorporating a\ntemporal as well as a more detailed spatial dimension.