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Evolutionary ecology

How to survive an alien invasion?

Sometimes fish can be just as scary as aliens – especially if you are a tiny Daphnia looking into the mouth of a big perch. Until 2006 daphnids in Lake Myravatn were unaware of the vertebrates living in neighbouring lakes. That year perch was illegally introduced and the daphnids had to face a novel death risk. So how do they cope with this alien invasion? PhD student Ingrid Wathne from EvoFish is determined to find out.

Photo:
Ingrid Wathne

Since 2009 Ingrid Wathne has been rowing around the lake, collecting samples every month in rain, wind, snow and sometimes sun, to gain new insights into the processes shaping the community and population structure. This she will achieve by studying the species composition of the plankton community as well as population structure and life history parameters of selected species. Data before 2009 have been sampled by other good rowers collecting data for the many PhD and Master theses based on the life in and around the lake.

Perch is size-selective when choosing its prey and very fond of large Daphnia crammed with eggs. Fortunately the Daphnia have the great ability to shape their life history according to the situation; when facing a predator preferring the big mamas, then it’s better to be a small mama, and Daphnia can do this.

Ingrid will continue her monthly boat trips throughout 2011 and shortly after she will reveal how, or if at all, the Daphnia in Lake Myravatn survived the alien invasion.