Meeting Abstract
77.5 Wednesday, Jan. 6 Effects of resource availability on dung beetle abundance and male horn size in Australian urban forest fragments BARTH, BJ*; FITZGIBBON, S; CARTER, AJ; WILSON, RS; Univ. of Queensland b.barth@uq.edu.au
The rate of urbanisation is increasing rapidly, with more than 50% of the world’s population now living in cities. Urbanisation drastically alters ecological communities via processes such as habitat loss, fragmentation, and degradation. Resource availability is important in explaining changes in ecological communities, with the availability of food resources dictating the abundance of a species and the development of condition-dependent traits. However the effects of altered resource availability in urban areas on such traits, especially those that are subject to sexual selection, are unclear. We examined how urbanisation affects the availability of the food resources and the resulting changes in abundance and condition of sexually selected traits of male dung beetles. Horn and body size of male dung beetles are important in male-male interactions and sexual selection, and are a function of food resource availability during larval development. In suburban Brisbane, the amount of macropod dung decreases in small urban forest fragments, while the amount of domestic dog dung greatly increases. This region is dominated by two species of dung beetle, Onthophagus tweedensis and O. dandalu, whose relative proportions in community assemblage vary in response to the urban gradient. O. dandalu is able to utilise dog dung and greatly increases in abundance in urban areas, while O. tweedensis is reliant on macropod dung and so decreases in abundance. The effects of resource availability on the abundance and condition of competing males have large implications for intra-specific interactions such as male-male competition and sexual selection. We are examining effect of resource availability on horn size, sex ratios and the presence of alternative male strategies for both species of dung species along the urban gradient.
