Genomic Signatures of Thermal Adaptation to Temperature in American Lobster

Identifying genetic basis of local adaptation to temperature is an important goal to achieve in a context of global warming. Genomics tools promise to improve our ability  to document evidence for local adaptation at genome-wide scale in non model species. Using RAD sequencing data, we performed environmental association analysis in concert with outliers analyses to fully highligh the possibility of local adaptation in a socio-economically important marine species: the American lobster. Outliers analyses revealed 41 SNPs putatively under divergent selection out of the 13,688 candidate SNPs genotyped among 19 sampling locations. Environmental associations revealed significant parallel temperature associated clines at 67 SNPs, suggesting a polygenic signal of adaptation to thermal habitat. In total, the combined approaches identified a list of 125 SNPs of which 28 SNPs are located in coding genes. Among these 28 SNPs, a gene coding for beta-galactosidase enzyme has been recorded as important for adaptation to temperature in many organisms. Comparison among the different methods reveal the advantages and the drawbacks of one to another as well as their common ground. Overall, the results of this project illustrate the potential of genomics tools for identifying adaptive genetic diversity that allows a species to respond to its environnement.