Do roads facilitate the spread of a native keystone and agricultural pest species in Neotropical savannas?
Ernane Vieira Neto (Ph.D. candidate)
Emilio M. Bruna (Advisor)
Abstract
Understanding how the spatio-temporal variation in landscapes affects species is a priority in ecology and conservation biology. Roads are prominent and frequent forms of landscape variation worldwide. To date the majority of studies investigating the effects of roads suggest they are deleterious for most species. However, an overlooked issue is the potential for some species to benefit from road creation and expansion, resulting in dramatic increases in their populations. This could be driven primarily by two contrasting demographic mechanisms: 1) increased recruitment and establishment of propagules or 2) favorable conditions for growth and survival of adults. Graduate student Ernane Vieira Neto (advised by Emilio Bruna) will test the relative importance of these mechanisms across space and time. Using experiments and observations, he will develop mechanistic distribution models linking local demographic processes and landscape-level patterns of species expansion with Atta leaf-cutter ants in the Brazilian Cerrado as the model system. Atta ants are native, dominant keystone herbivores of seminal ecological importance in the Neotropics, as well as agricultural pests responsible for millions of dollars of annual control expenses and losses to landowners. Alongside roads they are common features in the Cerrado - a biodiversity, economic, cultural and political hotspot severely threatened by unsustainable development and increasingly denser road networks. The goals are to assess the current distribution of Atta in the Cerrado, determine the effects of these mechanisms on Atta populations and how roads affect their relative importance, determine how inter-population variation in demography influences landscape-level patterns of distribution and abundance, and the potential resulting landscape changes. The conservation goals are to provide management information to landowners seeking to reduce their losses and the use of insecticides in crops and pastures, and also to decision-makers seeking appropriate sites to implement or improve reserves and manage road creation within or near these areas to reduce human impacts on the Cerrado.
