Beta diversity of aquatic macroinvertebrate assemblages associated with leaf patches in neotropical montane streams

Over 70% of the total channel length in all river basins is formed by low order streams, many of which originate on mountaintops. Headwater streams play fundamental roles in processing and transporting terrestrial and aquatic organic matter, often harboring high biodiversity in bottom leaf patches deposited from riparian vegetation. The objective of this study was to assess the variation in taxonomic composition (measured by beta diversity of aquatic macroinvertebrates) among stream sites located in the Espinhaço Meridional Mountain Range, part of a UNESCO Biosphere Reserve in eastern Brazil. We tested two hypotheses. i) Taxa turnover is the main reason for differences in aquatic insect assemblages within stream sites; we predicted that turnover would be higher than nestedness in all stream sites. ii) Stream site altitude and catchment elevation range are the main explanatory variables for the differences in beta diversity; we predicted that local stream site variables would account for...全球所有流域的河道总长度中，超过70%由低级别溪流构成，其中多数发源于山顶。源头溪流在陆地与水生有机质的加工及运输过程中发挥着核心作用，其河床底部因河岸植被沉积的叶片斑块往往孕育着极高的生物多样性。本研究旨在评估位于巴西东部联合国教科文组织（UNESCO）生物圈保护区组成部分——南埃斯皮尼亚苏山脉（Espinhaço Meridional Mountain Range）内各溪流样地的分类组成差异（以水生大型无脊椎动物的β多样性作为衡量指标）。本研究验证了两项假说：其一，类群更替是溪流样地内水生昆虫群落组成差异的主要成因，我们预测所有溪流样地中的类群更替程度均高于嵌套性程度；其二，溪流样地海拔与集水区海拔范围是造成β多样性差异的主要解释变量，我们预测，溪流样地的局地变量将能够解释……