Variation in the spatial structure of communities in terms of species composition (beta diversity) is affected by different ecological processes, such as environmental filtering and dispersal limitation. Large rivers are known as barriers for species dispersal (riverine hypothesis) in tropical regions. However, when organisms are not dispersal limited by geographic barriers, other factors, such as climatic conditions and geographic distance per se, may affect species distribution. In order to investigate the relative contribution of major rivers, climate and geographic distance on Passeriformes beta diversity, we divided Amazonia into 549 grid cells (1° of latitude and longitude) and obtained data of species occurrence, climate and geographic position for each cell. Beta diversity was measured using taxonomic, phylogenetic and functional metrics of composition. The influence of climatic variables, geographic distance and rivers on these metrics was tested using regression analyses. Passerine beta diversity is characterized mainly by the change in species taxonomic identity and in phylogenetic lineages across climatic gradients and over geographic distance. However, species with similar traits are found throughout the entire Amazonia. The size of rivers was proportional to their effect on species composition. However, climate and geographic distance are relatively more important than rivers for Amazonian taxonomic and phylogenetic species composition.

中文翻译：

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在亚马逊地区，气候和地理距离对河流的雀形目鸟类的β多样性影响比河流更大

就物种组成（β多样性）而言，社区空间结构的变化受不同的生态过程（例如环境过滤和扩散限制）的影响。大型河流被称为热带地区物种扩散的障碍（河流假设）。但是，当生物体的扩散不受地理障碍的限制时，其他因素（例如气候条件和地理距离本身）可能会影响物种分布。为了调查主要河流，气候和地理距离对Passeriformesβ多样性的相对贡献，我们将亚马逊河划分为549个网格单元（经度和纬度为1°），并获得了每个单元格的物种发生，气候和地理位置数据。Beta分类是通过分类学来衡量的，组成的系统发育和功能指标。使用回归分析测试了气候变量，地理距离和河流对这些指标的影响。雀形β多样性的主要特征是物种分类学特征的变化以及跨气候梯度和地理距离的系统发生谱系的变化。然而，在整个亚马逊河地区发现了具有相似性状的物种。河流的大小与其对物种组成的影响成正比。但是，对于亚马逊的生物分类和系统发育物种组成而言，气候和地理距离比河流重要得多。雀形β多样性的主要特征是物种分类学特征的变化以及跨气候梯度和地理距离的系统发生谱系的变化。然而，在整个亚马逊河地区发现了具有相似性状的物种。河流的大小与其对物种组成的影响成正比。但是，对于亚马逊的生物分类和系统发育物种组成而言，气候和地理距离比河流重要得多。雀形β多样性的主要特征是物种分类学特征的变化以及跨气候梯度和地理距离的系统发生谱系的变化。然而，在整个亚马逊河地区发现了具有相似性状的物种。河流的大小与其对物种组成的影响成正比。但是，对于亚马逊的生物分类和系统发育物种组成而言，气候和地理距离比河流相对重要。