85.2 Friday, Jan. 6 Gene expression predicts genetically-determined thermal tolerance in corals MEYER, E*; DAVIES, S; MATZ, MV; University of Texas - Austin; University of Texas - Austin; University of Texas - Austin EliMeyer@mail.utexas.edu
Genetic variation in thermal tolerance would be necessary for coral populations to adapt to warming ocean temperatures. However, despite widespread concern over degradation of coral reefs and intensive study of thermal stress responses, genetic variation in this trait has never been shown. We have addressed this experimentally by crossing parental colonies of Acropora millepora collected from distinct populations. The set of 30 families produced from this cross displayed a wide range of thermal tolerance during larval stages. Statistical analysis of half-sibling relationships revealed that thermal tolerance is highly heritable in these families (narrow sense heritability = 0.63), indicating a genetic basis for variation in this trait. To identify the functional basis of these differences, we profiled gene expression in a subset of families prior to exposure to thermal stress. We found that constitutive differences in gene expression were strongly correlated with subsequent thermal tolerance, identifying specific gene expression profiles that predict thermal tolerance. qPCR analysis of additional larval families confirmed the predictive power of these expression profiles. Our study has demonstrated for the first time a genetic basis for thermal tolerance in corals, and identified specific genes underlying this variation. These genes provide a plausible mechanistic link between genetic and phenotypic variation, and identify candidate targets of selection that can now be studied in the context of natural populations and episodes of thermal stress.