High spatial turnover in springtails of the Cape Floristic Region
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Aim The extraordinary diversity of plants across the Cape Floristic Region is characterized by considerable species turnover among sites. Phytophagous insects show similarly high turnover, but their patterns are closely coupled to those of their hosts. If the mechanisms underlying high plant turnover are not unique to plants, similar patterns of turnover should also be seen in non-herbivorous arthropod groups. We tested this hypothesis using new data for the Collembola fauna of the Fynbos biome. Location The south-western Cape, South Africa. Taxon Springtails (Hexapoda: Collembola). Methods We sampled springtails from six sites over two seasons. Species richness was compared with expected values from other studies worldwide given the environmental characteristics of the sites sampled. Nestedness and turnover components of beta diversity were calculated and compared against beta diversity patterns of springtails across Europe. Results A total of 114 morphospecies from 14 families was collected. Species richness of Fynbos sites ranged from 14 to 31 species, which was not significantly different to that previously reported for non-Fynbos locations and generally within expectations given the temperature, rainfall and productive energy of each site. Beta diversity was high across all pairwise comparisons of Fynbos sites and dominated by species replacement rather than assemblage nestedness. Relative to the distance between sites, Fynbos assemblages, with a median inter-site distance of 140 km, showed beta diversity substantially higher than in European assemblages, which had a median inter-site distance of 1,270 km. Main conclusions Alpha diversity of Fynbos Collembola assemblages is in keeping with species richness expectations. By contrast, beta diversity is high given the small distances among sites and is characterized predominantly by species turnover. These patterns of unremarkable alpha diversity, but high turnover among sites are comparable to many Fynbos plant groups. The mechanisms giving rise to high beta diversity of the plants may also have led to high diversity in other taxa.
- RESEARCH: CIB Associates