Diptera species and functional diversity across tropical Australian countryside landscapes

Abstract

Countryside landscapes are composed of a range of human-dominated ecosystems that now dominate the earth's terrestrial regions. In the tropics, the creation of these landscapes has shadowed the destruction of rainforests. Most studies of diversity across tropical countryside landscapes have focused on the taxonomic diversity of easily measured groups. Thus there are major gaps in our understanding of many ecologically important organisms in these landscapes. Here we examine the taxonomic and functional diversity of Diptera in countryside landscapes of Australia's wet tropics, focusing on some of the most common landscape elements in this region: forest remnants, forest edges, and open cattle pastures. We demonstrate that different landscape elements possess contrasting levels of dipteran diversity. Importantly, small forest fragments act as reservoirs of fly taxonomic diversity, but for some fly functional groups (pollinators and predators), small forest fragments and their edges have lower functional redundancy than larger forest patches and their edges. We also show that dipteran diversity is more positively associated with local forest cover than patch size alone. Our results complement the growing literature on ecologically important insect taxa in countryside landscapes around the world, and contribute to a greater understanding of how landscape modification likely impacts ecosystem functions and services at landscape scales.