Morphological traits and bioindicators: a case study on dung beetles in the Maputaland Centre of Endemism

Dung beetles have been identified as important indicators of habitat change in the Maputaland centre of Endemism, an area of southern Mozambique and northern Kwazulu-Natal in South Africa. Maptutaland harbours one of the rarest vegetation types, sand forest, of which only small portions are currently protected in four conservation parks of South. Sand forest habitats are rapidly undergoing transformation due to increasing elephant browsing activities that create a sand forest-mixed woodland matrix. It has been observed that dung beetle assemblages are significantly different in sand forest and mixed woodland habitats, and if elephant activity continues in sand forest patches, it is predicted that dung beetle assemblages will become more homogenous across habitats. Two habitats, namely undisturbed sand forest and mixed woodland, were sampled and I investigated the morphological differences (wing loading and aspect ratio) of wings across habitats using generalists and indicator species. Low wing loading combined with a high aspect ratio enhances lift production and take-off ability with a mechanical power output improving dispersal abilities in mixed woodland indicator species compared to sand forest indicators. Conversely, predictions regarding generalist species were rejected because they had overall similar wing morphology across habitats. Furthermore, if fragmentation of sand forest patches is not managed, dung beetles are expected to become constrained by their wing morphology and a homogeneous arthropod assemblage will occur across habitats. This could jeopardize long-term studies which use dung beetles to monitor the biodiversity and ecosystem functioning in the MC.