Inbreeding-Driven Innate Behavioral Changes in Drosophila melanogaster

SIMPLE SUMMARY: Inbreeding includes mating between two closely related individuals. It is known to affect the biological fitness of plants and animals, including humans. Experiments conducted on Drosophila melanogaster, a common fruit fly, demonstrate adverse effects of inbreeding on reproductive fitness and stress tolerance. However, the impact of inbreeding on the innate behavior of D. melanogaster is relatively unexplored. In this study, we bred D. melanogaster in a manner to attain different degrees of inbreeding in progeny flies. These flies were then assessed and compared for different behavioral traits. Our findings showed abnormalities in locomotor and phototactic behaviors due to inbreeding. Likewise, changes in aggression and courtship behavior with increasing levels of inbreeding were also observed. Interestingly, among positively phototactic flies, better learning ability was observed in inbred flies compared to outbred flies. Taken together, our study demonstrates that inbreeding influences the innate behavior of D. melanogaster. Given the reputation of D. melanogaster as one of the most effective animal models, the findings of this investigation could be exploited in animal and livestock breeding, conservation biology and genetic counseling. ABSTRACT: Drosophila melanogaster has long been used to demonstrate the effect of inbreeding, particularly in relation to reproductive fitness and stress tolerance. In comparison, less attention has been given to exploring the influence of inbreeding on the innate behavior of D. melanogaster. In this study, multiple replicates of six different types of crosses were set in pair conformation of the laboratory-maintained wild-type D. melanogaster. This resulted in progeny with six different levels of inbreeding coefficients. Larvae and adult flies of varied inbreeding coefficients were subjected to different behavioral assays. In addition to the expected inbreeding depression in the-egg to-adult viability, noticeable aberrations were observed in the crawling and phototaxis behaviors of larvae. Negative geotactic behavior as well as positive phototactic behavior of the flies were also found to be adversely affected with increasing levels of inbreeding. Interestingly, positively phototactic inbred flies demonstrated improved learning compared to outbred flies, potentially the consequence of purging. Flies with higher levels of inbreeding exhibited a delay in the manifestation of aggression and courtship. In summary, our findings demonstrate that inbreeding influences the innate behaviors in D. melanogaster, which in turn may affect the overall biological fitness of the flies.