Perhaps the most rapid response to environmental change is acclimation, when individual organisms adjust their physiology to cope with new environments. Although this process is widespread, we are just beginning to define the rates, limits, and underlying cellular mechanisms. Coral reefs are important systems for acclimation studies, as they provide roughly one billion people with food and income, yet are extremely vulnerable to temperature shifts. We measured the rate of acclimation to increased temperature in a reef-building coral, Acropora nana using a laboratory experiment (Figure below; Bay & Palumbi 2015 Genome Biol Evol). We found that individuals exposed to elevated temperatures for just 7 days showed higher resistance to acute thermal stress. Surprisingly, there was no shift in gene expression during acclimation, but the magnitude of transcriptional response to acute stress was significantly muted in acclimated individuals. To measure the extent to which acclimation occurs in a natural system, we conducted a reciprocal transplant of the coral Acropora hyacinthus between reef sites with different thermal regimes (Palumbi et al. 2015 Science). After a year, corals transplanted into a more thermally variable location acclimated, increasing their thermal tolerance. We also found evidence for adaptation; acclimation accounted for only half of the thermal tolerance differences between sites. Transcriptome data mirrored this finding; 74 genes showed expression plasticity, evidence of acclimation, while 71 genes exhibited signs of adaptation. Future work is focused on understanding the evolution of acclimation capacity across multiple species.
The role of plasticity in environmental response
Ross Cunning, Rachael A. Bay, Andrew C. Baker, Nikki Traylor-Knowles. Comparative analysis of the Pocillopora damicornis genome highlights role of immune system in coral evolution. Scientific Reports, 2018.
Luke Thomas, Noah H. Rose, Rachael A Bay, Elora H. Lopez, Megan K. Morikawa, Lupita Ruiz-Jones, Stephen R. Palumbi. Mechanisms of thermal tolerance in reef-building corals across a fine-grained environmental mosaic: Lessons from Ofu, American Samoa. Frontiers in Marine Science, 2018.
Rachael A. Bay, Eric B. Taylor, Dolph Schluter. Parallel introgression and selection on introduced alleles in a native species. Molecular Ecology, 2018.
Rachael A Bay, Stephen R Palumbi. Transcriptome predictors of coral survival and growth in a highly variable environment. Ecology and Evolution, 2016.
Rachael A Bay, Stephen R Palumbi. Rapid acclimation ability mediated by transcriptome changes in reef-building corals. Genome Biology and Evolution, 2015.
Stephen R Palumbi, Daniel J Barshis, Nikki Traylor-Knowles, Rachael A Bay. Mechanisms of reef coral resistance to future climate change. Science, 2014.