Leg length and bristle density both necessary for water surface locomotion are genetically correlated in water striders

Access to hitherto unexploited ecological opportunities is associated with phenotypic evolution and often results in significant lineage diversification. Yet, our understanding of the mechanisms underlying such adaptive traits remains limited.  Water striders have been able to exploit the water-air interface, primarily facilitated by changes in the density of hydrophobic bristles and a significant increase in leg length. These two traits are functionally correlated and are both necessary for generating efficient locomotion on the water surface. Whether bristle density and leg length have any cellular or developmental genetic mechanisms in common is unknown. Here, we combine comparative genomics and transcriptomics with functional RNAi assays to examine the developmental genetic and cellular mechanisms underlying the patterning of the bristles and the legs in Gerris buenoi and Mesovelia mulsanti, two species of water striders. We found that two gene duplication events in the genes beadex...