Abstracts (first author)
Genetics of feeding behaviour in Daphnia magna and its influence on infection risk
Pond sediments represent a primary source of infective stages of parasites of planktonic organisms. The time and the type of interaction with the sediment are therefore important determinants of infection risk. The fresh water planktonic crustacean Daphnia magna exhibits a highly variable and heritable phototactic behaviour which influences the time spent in proximity of the sediment. It has been shown that clones that spend more time nearer the sediment have a grater risk of infection. Even if suspension feeding is the primary feeding mechanism in D. magna, an alternative behaviour has been described in which small amounts of sediment are stirred up and filtered. This behaviour is expected to increase the encounter rate with parasite infective stages harboured in the sediment and, therefore, infection risk. In the present study we are testing this hypothesis by assessing the heritability of the behaviour and by measuring the infection rates of D.magna clones with different feeding behaviours, exposed to sediment banks of resting spores of the bacterial parasite Pasteuria ramosa. The study is being performed on a large number of clones derived from a quantitative trait loci (QTL) panel. This design allows us to explore the genetic mechanisms underlying the feeding behaviour of D. magna, an ecologically relevant trait expected to influence infection risk in natural environments.