Quantifying Rates of Evolutionary Adaptation in Response to Ocean Acidification

Abstract

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 franciscanus has vastly greater levels of phenotypic and genetic variation for larval size in future CO2 conditions 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.

How will Ocean Acidification Affect Baltic Sea Ecosystems? An Assessment of Plausible Impacts on Key Functional Groups

“…More sensitive early life-history stages of M. edulis from the Skagerrak have been shown to respond differently to ocean acidification: fertilization success increased at reduced pH (induced by high pCO 2 ) whereas subsequent larval shell growth was negatively affected, albeit only slightly (Renborg and Havenhand, unpublished results). Similar small negative effects on larval shell growth have also been reported in populations of M. edulis from the North Sea (Gazeau et al 2010;Bechmann et al 2011), and in related Mytilus species around the world (Kurihara et al 2009;Gaylord et al 2011;Sunday et al 2011). Early reports of the effects of ocean acidification on shell growth in adult M. edulis showed negative impacts (Gazeau et al 2007), a result that contrasts with those of Melzner and co-workers in the Kiel fjord (Thomsen et al 2010;Melzner et al 2011), although the latter might be expected to be a result of local adaptation to seasonally low pH-especially at such extreme levels (Melzner et al 2009b;Thomsen et al 2010).…”

Impacts of ocean acidification on marine shelled molluscs

“…This study emphasizes the need to assess the effects of ocean acidification on the whole life cycle and across multiple generations of shelled molluscs and other marine and estuarine species. Recently, Sunday et al (2011) have used a very original set-up aiming at estimating heritabilities and maternal effects (phenotypic and genotypic variations) at low pH and to use these estimates in order to simulate the species response to low pH over multiple generations. By applying these techniques to a sea urchin and a mussel, Sunday et al (2011) demonstrated that, although the sea urchin species have a lower population turnover rate, its phenotypic and genotypic plasticity might lead to a faster adaptation to OA than for mussels.…”

The Impact of Ocean Acidification on Reproduction, Early Development and Settlement of Marine Organisms

“…Similarly, calcification rate differed between source populations of Mercenaria spp. signifying possible genotypic variation [44], while maternal provisioning may safe guard larvae from a high CO 2 world and lead to differences in evolutionary responses between species including molluscs and echinoderms [46,75].…”