Moderate and extreme low-pH adaptive alleles revealed in a single generation selection experiment from standing genetic variation in the purple sea urchin, Strongylocentrotus purpuratus

Global climate change is resulting in rapid environmental shifts that will require adaptive evolution to enable population persistence. For many species, particularly those that are long lived, this adaptive process will rely on standing genetic variation. The purple sea urchin, Strongylocentrotus purpuratus, is a broadly distributed species that has shown potential to adapt to low pH conditions caused by climate change. However, little is known concerning the genetic variation underlying adaptation to differing degrees of pH selection, an important process due to the temporal and spatial variation in extreme pH events. We conducted a single generation selection experiment to identify the genetic variation underlying adaption of S. purpuratus to mild (pH 8.0) and extreme (pH 7.5) pH selection.