| 论文摘要： |
Disentangling the effects of dispersal mode on the environmental and spatial processes structuring biological assemblages is essential to understanding the mechanisms of species coexistence and maintenance. Here, we use field investigations to link dispersal mode with environmental and spatial processes that control stream macroinvertebrate assemblage structure across the Yarlung Zangbo Grand Canyon of Tibet (Tibetan Plateau). We sampled macroinvertebrates in streams that occur in 4 distinct regions. Each of these regions has a steep elevational gradient but different altitude ranges, climate types, and water replenishment sources. We classified macroinvertebrate taxa into passive and active dispersal mode groups to test whether macroinvertebrates with different dispersal modes responded differently to environmental and spatial processes. Our results showed that the assemblage structure of active dispersal groups was more strongly determined by environmental variables (habitat filtering/species sorting) than spatial factors both within and across regions. In contrast, the structure of passive dispersers was more strongly associated with spatial factors than environmental filtering in the entire study area and within lower canyon regions. However, spatial effects were not important for either type of dispersal group in the upper canyon regions, especially in the region with glacier-fed streams, indicating the predominance of species sorting processes in these harsh environments. Furthermore, the spatial structuring of assemblages became stronger as habitat filtering declined, which indicates a reduction in species sorting processes in less harsh environments. Our findings demonstrate diverse responses of macroinvertebrate assemblages to environmental and spatial processes across this poorly-known highland river system, and imply that dispersal mode influences the underlying mechanisms of community variation. |
