Specialisation in frog‐biting midges (Diptera: Corethrellidae): A landscape perspective

Abstract Generally, competition excludes pairs of phylogenetically close species across the landscape. However, habitat, food and behaviour differentiation facilitate co‐occurrence of syntopic species. The taxa of frog‐biting midges Corethrella are assumed to be specialists on calling male frogs, but little is known about how habitat gradients and frog‐species composition influence their distribution and permit their coexistence in continuous landscapes. Our aims were to understand how environmental gradients in habitat, sound frequencies and frog‐species composition influence Corethrella spp. distributions and if habitat and sound frequencies segregate their occurrence across a landscape. We also investigated if habitat selection reduces co‐occurrence of species that share similar acoustic niches. The study was conducted in 20 permanent plots in Central Amazonia using different sound attractants as baits to capture Corethrella species. Habitat gradients, sound frequencies and frog‐species composition all influenced distributions of Corethrella spp. However, these factors do little to avoid Corethrella co‐occurrence, and habitat selection did not reduce co‐occurrence of species attracted to the same sound frequencies. These results suggest that competition is unlikely to affect the distribution of adults and that other aspects, such as competition in the larval phase, may be more important to permit their coexistence. The two most abundant species showed strong negative correlations in abundances, potentially indicating competition among these species, but larval habitat specialisation is likely to be the most important cause of this pattern.