Lokala skillnader i konsumtion av påväxtalger och terrestra löv hos en differentierad population av Asellus aquaticus
That ecological and evolutionary processes can take place on the same time scale is a recent insight. Today we also know that they are directly linked to each other. In the lake Tåkern, in year 2000, there was a structural change when phytoplankton declined and submerged vegetation, mainly stoneworts began to spread. This led to evolutionary changes in the aquatic sowbug, Asellus aquaticus which had previously been limited to the reed, most likely feeding on detritus. But then, sowbugs could exploit the new habitat in stoneworts and a new food resource in terms of periphyton. The aim of this study was to investigate whether the differentiation of the populations has led to specialization in the ecological roles of sowbugs as shredder of coarse detritus and grazer of periphyton. The study was a laboratory experiment in which groups of sowbugs were feeding on decomposing alder (Alnus glutinosa) leaves or periphyton growing on tiles. The results showed that there was no specialization in the habitat-specific food. However, reed animals had a greater (31 %) grazing effect than the stonewort animal on periphyton. There was also a non-significant tendency for reed animals to consume more leaves than the stonewort animals. The conclusion is that the different populations are not different in their functional roles, but the reed animals consume approximate 25 % more food than the stonewort animals, possibly because of higher activity.