Defaunation and fragmentation erode small mammal diversity dimensions in tropical forests

Forest fragmentation and defaunation are considered the main drivers of biodiversity loss, yet the synergistic effects of landscape changes and biotic interactions on assemblage structure have been poorly investigated. Here, we use an extensive dataset of 283 assemblages and 105 species of small mammals to understand how defaunation of medium and large mammals and forest fragmentation change the community composition and diversity of rodents and marsupials in tropical forests of South America. We used structured equation models to investigate the relationship between small mammal species, functional and phylogenetic diversity with forest size, forest cover and the occurrence of medium and large mammals. The best-fit model showed that defaunation reduced functional diversity, and that species diversity of small mammals increased with forest patch size. Forest cover did not affect functional and phylogenetic diversity. Our results indicate that occurrence of medium and large sized mammals...森林片段化与动物区系丧失被视为生物多样性丧失的主要驱动因子，但目前针对景观变化与生物间相互作用对群落结构的协同效应的研究仍较为匮乏。本研究依托涵盖283个群落、105种小型哺乳动物的大规模数据集，旨在探究中型与大型哺乳动物的动物区系丧失以及森林片段化，如何改变南美洲热带森林中啮齿类与有袋类的群落组成及多样性。研究采用结构方程模型（Structural Equation Models），分析小型哺乳动物的物种多样性、功能多样性与系统发育多样性，与森林斑块面积、森林覆盖度以及中型与大型哺乳动物的种群存在状况之间的关联。最优拟合模型结果显示，动物区系丧失会降低功能多样性，而小型哺乳动物的物种多样性则随森林斑块面积增大而提升。森林覆盖度对功能多样性与系统发育多样性并无显著影响。本研究结果表明，中型与大型哺乳动物的种群存在状况……