Meeting Abstract
Scleractinian corals are severely threatened by rising ocean temperatures. Several recent studies have shown that some coral populations possess heritable genetic variation in thermal tolerance, providing raw material for adaptation to climate change. High seawater temperatures (36°C) and salinity (44 ppt) in the Arabian Gulf have likely selected for environmental stress tolerance in the local populations, presenting a unique resource for the study of corals’ adaptive potential in a warming climate. To investigate thermal tolerance phenotypes in these populations, we focused on aposymbiotic larval stages of Platygyra daedalea. Thermal tolerance (survival during heat stress) was measured in 64 controlled crosses generated from 12 parental colonies. We documented extensive genetic variation in thermal tolerance (h2=0.33), and identified families with contrasting tolerance phenotypes. To investigate the functional basis for these differences, larvae were exposed to factorial combinations of elevated temperature and salinity. To compare families’ transcriptional responses we sequenced and annotated a de novo transcriptome, which was used as a reference to profile gene expression using RNA-Seq. This snapshot of gene expression revealed higher expression of putative stress response genes in susceptible than tolerant families. To investigate the dynamics of gene expression more directly, we conducted additional crosses in a subsequent season and profiled changes in gene expression over time in tolerant and susceptible families. This study provides insights into the mechanisms through which stress tolerant corals persist in the Gulf, and ultimately into possible mechanisms through which corals may adapt to climate change.
