The rock pools on the Skerry islands of the Baltic Sea harbor freshwater communities often dominated by planktonic crustaceans of the genus Daphnia. We study the ecology and evolution of these Daphnia and their parasites. This project addresses aspects of local adaptation, metapopulation and metacommunity dynamics, inbreeding, parasitism, and genetic population structure. Methods include field surveys, experimental evolution and next generation sequencing.
The dynamics of Daphnia in Baltic rock pools have been studied intensively, and much is known about local extinction and colonization. This long-term research project was started by V. Ilmari Pajunen and his wife Irmeli in 1982. The backbone of the research are the assessment of presence/absence of the three Daphnia species in more than 500 rock pools twice a year and records of the Daphnia parasites. Besides these we have metadata for every pool in the study region. Experiments in the field and the laboratory complement this work.
The Daphnia populations in the rock pools are very dynamic across the years. For example, on average 17% of the rock pools are occupied by D. magna; 16% of the occupied pools go extinct per year, but re-colonization approximately balances this loss in the long run. Colonization is usually connected to founder events (genetic bottlenecks), which has a strong impact on the evolution of the system. Further factors that influence the metapopulation dynamics, include interspecific competition, the presence of parasites and predators, isolation in space, salinity, pH, organic matter and pool size.
Participants of the project:
- Basel University: Dieter Ebert, Jürgen Hottinger, Peter Fields, Andera Cabalzar
- Helsinki University: Ilmari and Irmeli Pajunen
- Tel Aviv University: Frida Ben-Ami
- CNRS, Montpellier: Christoph Haag