The global acidification of the earth’s oceans is predicted to impact biodiversity via physiological effects impacting growth, survival, reproduction, and immunology, leading to changes in species abundances and global distributions. However, the degree to which these changes will play out critically depends on the evolutionary rate at which populations will respond to natural selection imposed by ocean acidification, which remains largely unquantified. Here we measure the potential for an evolutionary response to ocean acidification in larval development rate in two coastal invertebrates using a full-factorial breeding design. We show that the sea urchin species Strongylocentrotus franciscanushas vastly greater levels of phenotypic and genetic variation for larval size in future CO₂conditions compared to the mussel species Mytilus trossulus. Using these measures we demonstrate that S. franciscanus may have faster evolutionary responses within 50 years of the onset of predicted year-2100 CO₂ conditions despite having lower population turnover rates. Our comparisons suggest that information on genetic variation, phenotypic variation, and key demographic parameters, may lend valuable insight into relative evolutionary potentials across a large number of species.

Jennifer M. Sunday^1*, Ryan N. Crim², Christopher D. G. Harley², Michael W. Hart¹

1 Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada, 2 Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada