Authors: Guo-Dong Han and Yun-Wei Dong
Climate-driven adaptive genetic variation is one of the most important ways for organisms to tolerate environmental change and succeed in altered environments. To understand rapid climate-driven evolution, and how this evolution might shift biogeographic distributions in response to global change, we measured the adaptive genetic variation to the local environment of a marine invasive species Mytilus galloprovincialis. The genetic structure of eight populations from the Mediterranean Sea, northeastern Atlantic, northeastern Pacific, and northwestern Pacific were determined using genome-wide screens for single nucleotide polymorphisms. The relationships of genetic variation to environmental (seawater and air) temperature were analyzed using redundancy analysis and BayeScEnv analysis to evaluate the impacts of temperature on the genetic divergences among these eight populations. We found that the genetic compositions were significantly different among populations and the adaptive genetic variation was associated with temperature variables. Further, we identified some genetic markers exhibiting signatures of divergent selection in association with environmental features that can be used in the future to closely monitor adaptive variation in this species. Our results suggest that divergent climatic factors have driven adaptive genetic variation in M. galloprovincialis over the past century. The rapid evolutionary adaptation has played a pivotal role in enabling this species to invade a wide range of thermal habitats successfully. Species like M. galloprovincialis that possess high levels of genetic variation may not only be especially capable of invading new habitats with different environmental conditions, but also poised to cope rapidly and successfully with rising global temperatures.