Wing phenotypic plasticity, quantitative genetics, modularity, and phylogenetic signal analysis revealed the niche partitioning in two fruit fly species, Bactrocera dorsalis and Zeugodacus cucurbitae

Fruit flies are among the most common insect pests in the world. The presence of many cryptic species and numerous fruit fly species sharing the same niche cause considerable difficulty in species identification. This study investigates the species-specific wing morphology of two fruit fly species ( Bactrocera dorsalis - BD and Zeugodacus cucurbitae - ZC) using a geometric morphometric tool. Both fruit flies were collected using species-specific pheromone traps from the same niche. We detected significant wing size and shape variability within and between the species. BD wing was more symmetrical than ZC, and fluctuation asymmetry (FA) and directional asymmetry (DA) are more prominently expressed in ZC . This is the first attempt to evaluate the modularity (by using three subsets in proximal-distal wing axis), quantitative genetic and phylogenetic signal analysis of BD and ZC, and this is the first report of the geometric morphometric analysis of ZC. The highly integrative wing system was observed in both species (except the left-wing of BD). We concluded that, through the quantitative genetic analysis, BD is a highly dispersing nature than the ZC. ZC and BD evolutionary separated in a distinct morphospace, and all characters (wing shape, size, and venation pattern) are derived based on their ecological conditions. These results are interpreted in terms of the interspecific competition of two fruit fly sharing the same niche, and the different levels of phenotypic wing plasticity response reduce rivalry and promote spatial resource partitioning.