Abstract
The knowledge of spatial pattern and geographic beta-diversity is of great importance for biodiversity conservation and interpreting ecological information. Tropical forests, especially the Amazon Rainforest, are well known for their high species richness and low similarity in species composition between sites, both at local and regional scales. We aimed to determine the effect and relative importance of area, isolation and climate on species richness and turnover in orchid bee assemblages among plateaus in central Brazilian Amazonia. Variance partitioning techniques were applied to assess the relative effects of spatial and environmental variables on bee species richness, phylogeny and composition. We hypothesized that greater abundance and richness of orchid bees would be found on larger plateaus, with a set of core species occurring on all of them. We also hypothesized that smaller plateaus would possess lower phylogenetic diversity. We found 55 bee species distributed along the nine sampling sites (plateaus) with 17 of them being singletons. There was a significant decrease in species richness with decreasing size of plateaus, and a significant decrease in the similarity in species composition with greater distance and climatic variation among sampling sites. Phylogenetic diversity varied among the sampling sites but was directly related to species richness. Although not significantly related to plateau area, smaller or larger PDFaith were observed in the smallest and the largest plateaus, respectively.
Highlights
The knowledge of spatial pattern of beta-diversity is of great importance for practical biodiversity conservation and interpreting ecological information [1]
The total sampling effort resulted in 486 h of sampling and the capture of 1,673 male orchid bees belonging to four genera and at least 55 species (S2 Table)
The species richness of orchid bees observed among the plateaus in the Amazonian Rainforest of Saraca-Taquera, Brazil, 55 species, is rivaled only by that observed in Tarapoto, Peru (50 species) [27] and central Panama [42]
Summary
The knowledge of spatial pattern of beta-diversity is of great importance for practical biodiversity conservation and interpreting ecological information [1]. Studies of patterns of diversity in the Amazon–the largest and richest rainforest biome in the world–have traditionally focused on a restricted number of well-known taxa, such as plants and vertebrates [2,3,4]. Tropical forests, especially the Amazon Rainforest, are well known for their high species richness and low degree of similarity in species composition among sites, both on local and regional scales [10, 1]; in other words, there are few common species among sites. Differences in species richness and composition among sites is attributed to beta diversity (or high species turnover among sites), as a result of heterogeneity in habitats and species dispersal limits [11,1, 12]. Contemporary spatial patterns of species richness are influenced by, among other factors, current climate [13,14,15], as well as historical events that influenced the geographical origins and distribution of clades [16,17]
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