Phylogenetic and morphological relationships between nonvolant small mammals reveal assembly processes at different spatial scales

The relative roles of historical processes, environmental filtering, and ecological interactions in the organization of species assemblages vary depending on the spatial scale. We evaluated the phylogenetic and morphological relationships between species and individuals (i.e., inter- and intraspecific variability) of Neotropical nonvolant small mammals coexisting in grassland-forest ecotones, in landscapes and in regions, that is, three different scales. We used a phylogenetic tree to infer evolutionary relationships, and morphological traits as indicators of performance and niche similarities between species and individuals. Subsequently, we applied phylogenetic and morphologic indexes of diversity and distance between species to evaluate small mammal assemblage structures on the three scales. The results indicated a repulsion pattern near forest edges, showing that phylogenetically similar species coexisted less often than expected by chance. The strategies for niche differentiation m...在物种集合（species assemblage）的构建过程中，历史过程、环境过滤与生态互作的相对作用随空间尺度而异。本研究针对共存于林草交错带（grassland-forest ecotones）的新热带区陆生小型哺乳动物（Neotropical nonvolant small mammals），分别在三个空间尺度下评估其物种与个体间的系统发育关系及形态学关联——三个尺度分别为景观尺度、区域尺度，以及种间与种内变异（inter- and intraspecific variability）层面。本研究借助系统发育树（phylogenetic tree）推演演化关系，并以形态性状（morphological traits）作为物种与个体间功能表现与生态位（niche）相似度的指示指标。随后，本研究通过物种间的系统发育与形态多样性指数及距离指数，对三个尺度下的小型哺乳动物物种集合结构进行了评估。研究结果显示，林缘附近存在系统发育排斥模式，即系统发育相似度较高的物种共存概率低于随机预期水平。生态位分化策略……