Abstracts (first author)
Potential and constrains of adaptation to ocean acidification in the globally important marine phytoplankton species Emiliania huxleyi
The biological impacts of climate change and the associated acidification of the surface ocean are intensely studied, with likely consequences for biodiversity and ecosystem functioning emerging as a consensus. However, evolutionary responses have only recently been considered. Marine microbes with short generation times and large population size are good candidates for testing the evolutionary potential to respond to ocean acidification. We used the globally important marine phytoplankton species Emiliania huxleyi for a 1000 generation selection experiment in elevated CO2 and found that adaptive evolution to ocean acidification is possible and likely fast enough to act on time scales relevant to climate change. Replicate populations selected under high CO2 consistently revealed higher fitness than control populations under ocean acidification conditions. To investigate whether such phenotypic convergence involves the same or different mutations, we exposed adapted populations to a novel environment where pleiotropic effects can serve as a proxy for divergent genetic bases of previous adaptation to high CO2. We identified divergent functional genetic bases in replicate high CO2 adapted but not in control populations. This indicates that many evolutionary trajectories to high CO2 adaptation are possible in E. huxleyi but also suggests that pleiotropy may constrain adaptation of natural E. huxleyi populations to ocean acidification. Our results highlight the urgent need to consider evolutionary processes when assessing the responses of marine microbes to future ocean conditions.