116.1 Saturday, Jan. 7 Evidence of local thermal adaptation in a Caribbean coral KENKEL, C.D.*; GOODBODY-GRINGLEY, G.; BARTELS, E.; DAVIES, S.W.; PERCY, A.L.; MATZ, M.V.; The University of Texas at Austin; Bermuda Institute of Ocean Sciences; Mote Tropical Research Laboratory; The University of Texas at Austin; The University of Texas at Austin; The University of Texas at Austin email@example.com
The long-term persistence of coral reefs under global climate change scenarios depends largely on the ability of corals to track increasing temperatures with evolutionary adaptation. However, the patterns and mechanisms of coral adaptation to varying thermal environments remain poorly understood, particularly in the Caribbean. In the Florida Keys, nearshore corals are exposed to temperature extremes in both the summer and winter, while offshore corals experience a less variable thermal environment. We hypothesized that these spatial differences in temperature result in local thermal adaptation, with inshore corals exhibiting greater resilience to thermal stress than offshore corals. To test this prediction, we conducted a six-week common garden experiment with colonies of the mustard hill coral, Porites astreoides, from inshore and offshore reefs, using water temperature as a selective agent. Growth, bleaching and algal symbiont photosystem function were quantified as proxies of fitness. We also measured expression of genes implicated in stress response, metabolism, and immunity in the coral host to identify underlying molecular pathways affected by long-term thermal stress. We find significant genotype by environment interactions for symbiont related traits, suggesting that inshore corals are more resilient to thermal stress. Ongoing analysis of genotype data will provide insight into the relative roles of genetic and physiological mechanisms potentially driving local thermal adaptation in this system.