Description
Mini-talk + poster
Differences in environmental conditions can drive divergent selection towards locally adapted ecotypes. In sticklebacks (Gasterosteus aculeatus), parasites are a major environmental factor, exerting strong selection pressure with regards to reproduction, predation and growth. These parasite communities vary strongly between habitat types (e.g. river or lake), imposing a need for ecotype dependent local adaptation of parasite resistance. Hence, stickleback ecotypes of similar origin (e.g. river or lake) should have evolved comparable parasite-specific resistance best suited for their respective habitat. To test whether this holds true on a global scale we exposed lab bred Canadian and German sticklebacks to a typical lake parasite, the trematode Diplostomum pseudospathaceum. Each fish was individually exposed to 100 Diplostomum cercariae and sacrificed 24h after exposure to measure infection rate and collect tissue samples for gene expression analysis (including sham-exposed controls). Our results show parallels in the discrepancy pattern for infection rates between Canadian and German river/lake pairs, with river fish exhibiting a generally higher infection rate than lake fish. We further investigated the underlying gene expression patterns of immune relevant genes to unravel the mechanistic basis for the convergent evolution between the river/lake pairs. Focusing on innate immune genes in particular, we find similar response patterns within ecotypes.
