Genetic analyses of allelic variation in cGMP-dependent protein kinase and troponin-1 and their effects on behaviour

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Investigating the genetic basis of complex traits like longevity, disease resistance, and behaviour is challenging since they are influenced by numerous genes and by fluctuations in the environment. The lability and complexity of behaviours like foraging are ideal for investigating the evolutionary genetics of complex traits. Foraging in larval fruit flies, Drosophila melanogaster, is largely influenced by natural allelic variation in the foraging gene (for). These alleles confer a natural behaviour polymorphism where rovers (forR) and sitters (fors) differ in their movement rates between and within food patches. New preliminary evidence suggests that foraging behaviour is also influenced by natural allelic variation in a modifier gene wings up A (wupA). wupA decreases rover foraging behaviour to a sitter level. In mammals the cGMP-dependent protein kinase, encoded by for, phosphorylates the Troponin-I (TnI) protein encoded by wupA. TnI is an important regulator of muscle contraction and is likely involved in the muscle output of food search behaviours. I propose to further investigate the role of epistatic interactions between wupA and for by first confirming a behavioural role for wupA using quantitative trait locus mapping and complementation tests with mutants in both wupA and for. I will measure the relative behavioural implications of natural allelic variation in for and wupA by introgressing alleles of wupA and for. Given that previous analyses have shown a role for negative frequency-dependent selection in maintaining allelic variation in for, I will investigate whether variation in wupA plays a role in the maintenance rovers and sitters. Finally, I propose to begin assessing the population genetics and molecular evolution of alleles in for/wupA by looking for signatures of positive selection in alignments of for and wupA from the genome sequences of 12 Drosophila species. I will then extend these analyses to a series of inbred lines that were recently derived from a natural population. Understanding the dynamic epistatic interactions between for and wupA on foraging behaviour provides a unique avenue and model system for studying complex trait evolution.