An increase in ocean acidity could drive substantial genetic change in sea urchins in just one generation.

Melissa Pespeni at Hopkins Marine Station in Pacific Grove, California, and her colleagues housed developing purple sea urchins (Strongylocentrotus purpuratus) under current acidity levels and the higher levels that are expected from increasing amounts of carbon dioxide in the atmosphere. The authors measured changes in the frequency of 19,493 genetic variants as fertilized eggs grew into swimming and feeding larvae. Although conditions of high acidity had little effect on the growth of the animals, major shifts occurred in genes that code for 40 classes of proteins. These changes were concentrated in genes related to the construction of urchins' shells and how the organisms regulate metabolism and pH.

Increased acidity could be selecting for genetic variants that improve survival under these conditions, the researchers suggest.

Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1220673110 (2013)