Genetic variations in foraging habits and their developmental noise in Drosophila

Investigating the causes and consequences of niche partitioning in populations is a significant goal in ecology and evolutionary biology. Studies have examined genetic and environmentally induced variations in resource utility and their ecological implications. However, few have explored developmental noise or instability as a factor contributing to variation in resource utility. Here, we studied genetic variation, and developmental noise in foraging traits of Drosophila lutescens, a wild fruit fly. Using 70 iso-female lines from a single population, we observed two foraging behavior traits - locomotive activity and resource preferences - in an experimental "8"-shaped arena with two different fruit juices in each chamber. The mean locomotive speed and relative preference for orange juice over grape juice varied significantly among iso-female lines, indicating genetic variation in foraging behavior. Additionally, the degree of variation within iso-female lines also varied, showing relatively higher heritability. While the locomotive speed and resource preferences of each line did not correlate with each other, the strength of variation within iso-female lines for locomotive speed showed a significant correlation with that for resource preferences. This suggests that the degree of developmental noise in both locomotive activity and resource preferences is governed by a shared genetic basis. Consequently, developmental noise can contribute to increased phenotypic variation in resource utility within a population and may evolve through natural selection.