The relationship between morphology and flight in Drosophila: a first approach to its genetic basis

Flight is a crucial activity for winged insects, involving diverse behaviours, and wing morphology has often been proposed as a key factor influencing flight capacity. Traits such as wing loading, wing:ratio, and wing aspect ratio have been suggested as targets of natural selection, exhibiting environmental and genetic variability. Here, we evaluate the relationship between morphological traits and two aspects of flight performance: flight duration (PTF) and its robustness (CVPTF) in Drosophila melanogaster. Additionally, we investigate the genetic basis of PTF and CVPTF. Our findings highlight two main insights. First, while genetic variation was detected in both morphological and flight traits, variability was considerably lower in the first case compared to the second one. This likely explains the absence of a strong relationship between these traits. Furthermore, among 107 candidate genes detected for flight traits, only a few were associated with wing morphology, reinforcing the weak link between morphology and performance. Second, we observed a negative relationship between PTF and CVPTF across sexes. However, CVPTF was associated with more polymorphisms and candidate genes than PTF, and only three genes (if, fru, and nAChRα5) were associated with both traits. These results suggest that both flight traits present distinct genetic bases.In conclusion, our results challenge the hypotheses that emphasize that wing morphology is determinant for flight performance. We also provide a first approximation to the genetic basis underlying two flight estimators, advancing our understanding of this behavioural trait in Drosophila.