In Search of Food: Exploring the Evolutionary Link Between cGMP-Dependent Protein Kinase (PKG) and Behaviour

Despite an immense amount of variation in organisms throughoutthe animal kingdom many of their genes show substantial conservationin DNA sequence and protein function. Here we explore the potentialfor a conserved evolutionary relationship between genes andtheir behavioural phenotypes. We investigate the evolutionaryhistory of cGMP-dependent protein kinase (PKG) and its possibleconserved function in food-related behaviours. First identifiedfor its role in the foraging behaviour of fruit flies, the PKGencoded by the foraging gene has since been associated withthe maturation of behaviour (from nurse to forager) in honeybees and the roaming and dwelling food-related locomotion innematodes. These parallels encouraged us to construct proteinphylogenies using 32 PKG sequences that include 19 species.Our analyses suggest five possible evolutionary histories thatcan explain the apparent conserved link between PKG and behaviourin fruit flies, honey bees and nematodes. Three of these raisethe hypothesis that PKG influences the food-related behavioursof a wide variety of animals including vertebrates. Moreover,it appears that the PKG gene was duplicated some time betweenthe evolution of nematodes and a common ancestor of vertebratesand insects whereby current evidence suggests only the for-likePKG might be associated with food-related behaviour.