Evolutionary Ecology of Adaptation to Toxic Dinoflagellates in a Marine Copepod
Thursday, May 26, 2011
Redfield Auditorium - 12:00 Noon
Dr. Hans G. Dam
Professor and Associate Head, Department of Marine Sciences, University of Connecticut
Adaptation (resistance or tolerance) to toxic dinoflagellates among grazers has important consequences for the transfer of toxins up the food chain, and for bloom control. In common-environment experiments with the copepod Acartia hudsonica and toxic dinoflagellate Alexandrium spp., we document between-population variation in traits that lead to differential fitness. Copepod populations with longer and more frequent exposure history are more tolerant to the toxic dinoflagellates than those unexposed or with little exposure. Toxic dinoflagellates exert a fitness penalty on less tolerant populations both through reductions in ingestion and egg production and through higher mortality. Differences in fitness between populations have the potential to lead to rapid evolution. Among tolerant individuals, there are also phenotypic differences in reproduction that lead to variations in the costs and advantages of tolerance, which are consistent with heterozygote dominance. We hypothesize that toxin tolerance is widespread and possibly underlain by a simple genetic system. We document two isoforms of the sodium channel of A. hudsonica. Future work will focus on linking sodium channel genotypes to phenotypic performance.