The effects of dispersal ability on metacommunity structure of macroinvertebrates in subtropical Chinese high-mountain streams: seasonal shifts in relative contribution of local environment and spatial processes.

It is generally recognized that dispersal mode can affect the relative role of environmental and spatial factors in structuring biotic communities. Disentangling the effects of dispersal mode on metacommunity structuring is essential to understanding the mechanisms of community assembly. Despite high seasonal variation in assemblage structure and phenological features of lotic macroinvertebrates, few studies examined the seasonal changes in the relative contribution of environmental and spatial processes. Here, we used two-season (spring and autumn) investigation data to link dispersal mode with local environmental and spatial factors that regulate macroinvertebrate metacommunity in a Chinese high-mountain stream network. Our aims were (1) to disentangle the relative role of environmental and spatial processes on structuring macroinvertebrate with different dispersal ability (aquatic passive: AqPa, terrestrial passive: TePa, and terrestrial active: TeAc) and (2) to determine seasonal shifts in metacommunity structuring processes. We found that assemblages of TeAc (with highest dispersal capacity) in both seasons were influenced more by environmental filtering than spatial structuring, whereas assemblages of TePa were mainly determined by spatial processes. Unexpectedly, AqPa group showed low spatial control in both seasons, probably due to their underestimated dispersal capacity via animal vector. The relative role of environmental and spatial factors was broadly stable across two seasons for AqPa and TeAc groups, but the TePa showed seasonal differences in the relative role of spatial factors, because of their seasonally changing dispersal capacity. In summary, our study emphasizes the use of dispersal mode for understanding metacommunity structuring mechanisms.