Loss of genetic diversity as a consequence of selection in response to high pCO₂

Standing genetic variation may allow for rapid evolutionary response to the geologically unprecedented changes in global conditions. However, there is little known about the consequences of such rapid evolutionary change. Here, we measure genetic responses to experimental low and high pCO ₂ levels in purple sea urchin larvae, Strongylocentrotus purpuratus. We found greater loss of nucleotide diversity in high pCO ₂ levels (18.61%; 900 μatm) compared to low pCO ₂ levels (10.12%; 400 μatm). In the wild, this loss could limit the evolutionary capacity of future generations. In contrast, we found minimal evidence that purple sea urchin larvae physiologically respond to high pCO ₂ through alternative splicing of transcripts (11 genes), despite a strong signal of alternative splicing between different developmental stages (1193 genes). However, in response to high pCO ₂, four of the 11 alternatively spliced transcripts encoded ribosomal proteins, suggesting the regulation of translation as a potential response mechanism. The results of this study indicate that while the purple urchin presently may have enough standing genetic variation in response to rapid environmental change, this reservoir of resilience is a finite resource and could quickly diminish.