Evolutionary adaptation to global change? Examples from the base of the marine food web
Friday seminar by Thorsten Reusch
Will populations and species adapt to global change? ‐ is a key question in marine ecology and evolutionary biology. I present examples from the base of the marine food web where our group studies adaptive genetic variation and its genetic basis in diverse photoautotrophs. In marine flowering plants (seagrasses), we used a space‐for time substitution design to address how gene expression patterns are correlated with thermal tolerance across southern and northern Zostera marina (eelgrass) populations, exposed to a summer heat wave in a common stress garden. Interestingly, the transcriptomic response only diverged after the stress during recovery, with southern genotypes rapidly returning to control gene expression, while northern ones revealed many genes indicative for protein degradation. Accordingly, we propose transcriptomic resilience, the return to normal (control) gene expression, as one measure of genotypes/populations to cope with global change associated stress. Phytoplankton species are amenable to more direct tests of evolutionary adaptation owing to short (~1 day) generation times. In an experimental evolution approach using the coccolithophore Emiliania huxleyi, we are studying adaptation to ocean acidification in both, mono‐clonal and multi‐clonal replicated selection lines after 1000 generations of propagation. As important correlated traits, calcification was partly restored as a result of adaptation, indicating the potential biogeochemical implications of our findings for the ocean’s potential to sequester excess anthropogenic carbon. Gene expression studies address the question whether or not the same genetic solutions are underlying identical phenotypes. Taken together, I will argue that evolutionary responses need to be taken into account when projecting biological effects of global change.
Prof. Dr. Thorsten B. Reusch
Head of Research Division - Marine Ecology
GEOMAR | Helmholtz Centre for Ocean Research Kiel