Diversity, distribution and community composition of Empididae, Hybotidae and Brachystomatidae(Insecta: Diptera) in Thailand – how did they arise?

Abstract

Current knowledge of Empididae, Hybotidae and Brachystomatidae (Insecta: Diptera) in Thailand is summarized and likely diversity estimated. Currently 131 species are known but the total fauna is estimated to be 328–825 species. Rich communities are associated with many biotopes but moist evergreen forests are especially diverse. Biogeographic af fi nities at generic level and community-level distribution of taxa along environmental gradients (habitat, ecological characters, seasonality, altitude, etc.) are combined with endemicity mapping and parsimony analysis of endemism to infer how empidoid communities might have responded to historical environmental changes. A General Historical Model of empidoid communities in Thailand is presented in which (i) the onset of the monsoon cycle forced altitudinal migration of “rainforest” biota to higher elevations where seasonality was relaxed and moist conditions prevailed throughout the year, (ii) orogenesis promoted speciation as mountain ranges became higher and more isolated, (iii) developing mountain chains provided continuity and immigration “corridors” effectively connecting Thailand’s mountains with others further north and south and (iv) oscillating climatic conditions, especially during recent glacial periods, caused repeated changes in sea-level and expansion and contraction of lowland seasonal forests encouraging migration from north and south.

Keywords

• biogeography
• diversity
• abundance