Exploring the Role of the Foraging Gene on Egg-laying Preferences in Drosophila melanogaster

Egg-laying decisions can have significant fitness consequences. In female Drosophila melanogaster, egg-laying involves foraging-like behaviour. Natural allelic variation in foraging (for) underlies the rover/sitter foraging behaviour polymorphism found in D. melanogaster. for encodes a cGMP-dependent protein kinase (PKG) where rovers have higher for-PKG transcript levels and PKG activity than sitters. Interestingly, the orthologue of for in nematodes (egl-4) affects both egg-laying and foraging behaviours. When given a choice between low- and high-nutrient patches, rovers preferentially lay more eggs on the low-nutrient patches while sitters and a sitter mutant prefer high-nutrient patches. Using the neuronal driver elav-GAL4, rover-like preferences were rescued in sitter flies. Compared to sitters, rovers have higher fitness on a sub-optimal substrate which may explain the observed egg-laying preferences. By studying the link from genes to behaviour, this study provides insight to the evolutionary basis and maintenance of behaviour.MAS