Separating species in terms of dispersal capacity can be useful to understand how local and regional factors affect the distribution of organisms in metacommunities. In this study, we sought to unravel how the characteristics of local habitats and spatial distances structure fish communities in Amazonian streams. We hypothesized that fishes classified with high dispersal capacity are mainly structured by mass effects and respond to environmental and spatial variables in the same proportion, while fishes classified with low dispersal capacity are mainly structured by species sorting, responding mainly to local environmental variables. We collected fish from 36 well-preserved streams in the Capim river basin in northern Brazil during the dry season. In general, the community composition was structured by characteristics of the local habitat. Spatial variables influenced each group at different intensities, agreeing with the models of species sorting and mass effects and corroborating our hypotheses. Thus, our findings suggest that the dispersal mode affects how metacommunities are structured. The differences in the patterns observed between the groups compared can help in the management and conservation of species, such as those with greater environmental requirements and more susceptible to habitat changes. We emphasize the need to maintain habitat integrity and connectivity in headwater streams to conserve species in their habitats.

根据扩散能力将物种分开可能有助于了解本地和区域因素如何影响有机体在有机群落中的分布。在这项研究中，我们试图揭示当地栖息地的特征和空间距离如何构成亚马逊河流域的鱼类群落。我们假设，具有高分散能力的鱼类主要由质量效应构成，并且对环境和空间变量的反应比例相同，而具有低扩散能力的鱼类主要由物种分类构成，主要对局部环境变量起作用。在干旱季节，我们从巴西北部的卡皮姆河流域的36个保存完好的溪流中采集了鱼类。一般而言，社区组成是由当地栖息地的特征构成的。空间变量以不同的强度影响每个组，这与物种分类和质量效应的模型相符，并证实了我们的假设。因此，我们的发现表明，分散模式会影响元社区的结构。所比较的各组之间观察到的模式差异可有助于物种的管理和保护，例如对环境有更高要求且更容易受到生境变化影响的物种。我们强调必须保持源头水流中栖息地的完整性和连通性，以保护其栖息地中的物种。所比较的各组之间观察到的模式差异可有助于物种的管理和保护，例如对环境有更高要求且更容易受到生境变化影响的物种。我们强调必须保持源头水流中栖息地的完整性和连通性，以保护其栖息地中的物种。所比较的各组之间观察到的模式差异可有助于物种的管理和保护，例如对环境有更高要求且更容易受到生境变化影响的物种。我们强调必须保持源头水流中栖息地的完整性和连通性，以保护其栖息地中的物种。