Meeting Abstract
Two populations of marine mussel, Mytilus californianus, reside along the Oregon coast and experience marked differences in environmental and oceanographic conditions despite being only 65km apart. Previous research suggests these populations experience high levels of gene flow resulting in genetically homogeneous populations. However, recent growth and DNA methylation data from long-term reciprocal transplant experiments suggest these mussels may establish metabolic patterns that allow for optimal growth under oceanographic conditions specific to the region they first settled and that DNA methylation may explain these locally adapted phenotypes. In invertebrates, hypermethylation of genes is predicted to protect housekeeping genes from variation, while hypomethylation in inducible genes are predicted to allow for variation of genes; thus allowing for locally adapted phenotypes or physiological plasticity. We used an in silico approach to predict the expected level of DNA methylation in housekeeping and inducible genes from these two mussel populations. Our data confirms these DNA methylation patterns previously seen in other invertebrates. Secondly, we performed digital gene expression analysis to identify differentially expressed genes between the two populations and found genes related to two biological functions, immune response and DNA repair, to be enriched in mussels from one population. From our in silico analyses, several genes associated with these biological functions display high CpG O/E ratios, suggesting they are subject to low levels of methylation and potentially greater variation in expression. We are currently working to identify differences in methylation status for genes that show differential expression between populations.
