Meeting Abstract
Efforts to manage and conserve coral reefs are hindered by a fundamental and as yet unanswered question—What makes a coral good at living in its particular environment? Reciprocal transplant experiments have improved our understanding of local adaption. Corals are indeed often better at living in their ‘home’ environment than alternate ones. But it remains unclear to what extent this results from genetic adaptation as opposed to developmental (canalized) plasticity, a question that could impact success or failure when recolonizing degraded reefs. Here we use genome-wide genotyping (2bRAD) to test for evidence of spatially varying selection between proximate (< 10km apart) but environmentally distinct reefs. We sampled juvenile (less than 2 years old) and adult individuals of two bouldering corals Siderastrea siderea and Montrastraea cavernosa to examine how allele frequencies change through time at the alternate reefs. Specifically we test the hypothesis that purifying selection leads to genetically distinct adult populations. If this is the case, adult colonies should display elevated structure compared to juvenile counterparts because purifying selection among the young juveniles is largely incomplete. Analyses of FST across the genome indicate that adults indeed display generally higher FST between reefs than juveniles. More importantly, adults show higher incidence of extreme FST values, suggestive of genetic regions under local selection. The results indicate the potential importance of small-scale spatially varying selection in producing locally adapted coral populations.
