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Free keywords:
floodplain; rainforest; inundation forest; coexistence; activity pattern; niche separation; species richness
Abstract:
Studies on tiger beetle guilds are promising to shed light on general mechanisms that maintain species diversity in the tropics. Therefore this family was studied across a range of habitat types of Central Amazonia in the vicinity of Manaus (open areas and forests on terra firme as well as in white-, mixed-, and blackwater floodplains). In addition to analysis of regional species distribution (extents of habitat specificity), local spatio-temporal guild structures were investigated in order to infer mechanisms mediating coexistence within guilds. Here the results of extensive field observations on habitats, life cycles, and behaviour are summarised for both larvae and adult beetles of most of the 25 species known to occur in the region. Field work was carried out from 1991-99, of which 2-6 years were spent in each habitat. Additionally, life cycles of species were studied by rearing them in the laboratory. At the regional scale, species richness is related with regional habitat diversity, likely because habitat specificity is strong in most species. At the local scale, spatio-temporal guild structure is determined by different life cycles, diel activity patterns, microhabitat preferences and behaviour. Guild structures vary according to habitat types. Guilds from open floodplain areas show strong niche separation whereas guilds from terra firme forest floors exhibit wide niche overlap, with floodplain forests and open terra firme areas lying in between. Thus, tiger beetle guilds of Central Amazonia seem to be variously structured, which indicates different mechanisms mediating coexistence. Possible relations of guild structure with habitat properties are discussed
