Temporal segregations in the surface community of an ephemeral habitat: Time separates the potential competitors of coprophilous Diptera

摘要

Temporal separations among species greatly enhance the species' coexistence, especially in insect communities inhabiting temporally unstable, yet resource-rich, ephemeral habitats like dung or carrion. The insect communities inhabiting ephemeral habitats consist of two components, the internal community dwelling within the substrate (mostly Coleoptera), and the surface community inhabiting the habitat's outer rim (mostly adult Diptera). In contrast to the internal community, the surface community is very rarely studied. We present here the first quantitative study of temporal trends in the surface community of coprophilous dipteran adults. Using artificially created 1.5 L cow dung pats, we studied the succession and seasonality in the surface community during six sampling periods in 2011 and 2012. In total, we sampled 13579 adults of dung-visiting Diptera. Both the abundance and species richness decreased rapidly throughout the succession, and were highest during summer. Along the successional gradient, the community was separated into two main groups (early and late) and four subgroups: (i) species occurring during the first few hours (mainly Calyptratae: Diptera); (ii) species occurring between the first and second days; (iii) species occurring between the second and third days (mainly Acalyptratae: Diptera); and (iv) species with optima after the third day of dung pat existence (mainly Nematocera). The earliest and latest successional groups, occurring mainly during spring-autumn, were seasonally separated from the two mid-successional groups, occurring during summer. The ecologically similar species displayed detectable seasonal micro-optima, which likely facilitate their coexistence. There was a high overall similarity in temporal patterns between dung and carrion surface communities.