Burt, J. A. | bioRxiv Science

bioRxiv2018

Intergenerational epigenetic inheritance in reef-building corals

MainThe notion that intergenerational or transgenerational inheritance operates solely through genetic means is slowly being eroded: epigenetic mechanisms have been shown to induce heritable changes in gene activity in plants 1,2 and metazoans 1,3. Inheritance of DNA methylation provides a potential pathway for environmentally induced phenotypes to contribute to evolution of species and populations 1-4. However, in basal metazoans, it is unknown whether inheritance of CpG methylation patterns occurs across the genome (as in plants) or as rare exceptions (as in mammals) 4. Here, we demonstrate genome-wide intergenerational transmission of CpG methylation patterns from parents to sperm and larvae in a reef-building coral. We also show variation in hypermethylated genes in corals from distinct environments, indicative of responses to variations in temperature and salinity. These findings support a role of DNA methylation in the transgenerational inheritance of traits in corals, which may extend to enhancing their capacity to adapt to climate change.

genetics↗

bioRxiv2017

Genomic and transcriptomic signals of thermal tolerance in heat-tolerant corals (Platygyra daedalea) of the Arabian/Persian Gulf

Scleractinian corals occur in tropical regions near their upper thermal limits, and are severely threatened by rising ocean temperatures. Ocean warming leads to loss of symbiotic algae (Symbiodinium), reduced fitness for the coral host, and degradation of the reef. However, several recent studies have shown that natural populations of corals harbor genetic variation in thermal tolerance that may support adaptive responses to warming. Here weve extended these approaches to study heat tolerance of corals in the Persian/Arabian Gulf, where heat-tolerant local populations have adapted to warm summer temperatures (>36{degrees}C). To evaluate whether selection has depleted genetic variation in thermal tolerance, estimate the potential for future adaptive responses, and understand the functional basis for these corals unusual heat tolerance, we measured thermal tolerance using controlled crosses in the Gulf coral Platygyra daedalea. We found that heat tolerance is highly heritable in this population (0.487-0.748), suggesting substantial potential for adaptive responses to selection for thermal tolerance. To identify genetic markers associated with this variation, we conducted genomewide SNP genotyping in parental corals and tested for relationships between paternal genotype and thermal tolerance of the offspring. We found that multilocus SNP genotypes explained a large fraction of variation in thermal tolerance in these crosses (69%). To investigate the functional basis of these differences in thermal tolerance, we profiled transcriptional responses in tolerant and susceptible families, revealing substantial sire effects on transcriptional responses to thermal stress. We also studied sequence variation in these expressed sequences, identifying alleles and functional groups associated with thermal tolerance. Our findings demonstrate that corals in these populations harbor extensive genetic variation in thermal tolerance, and these heat-tolerant phenotypes differ in both gene sequences and transcriptional stress responses from their susceptible counterparts.

evolutionary biology↗