Drought alters the structure and functional traits of soil nematodes

We evaluated the impact of drought on the abundance of nematode functional groups within their community and the body size of communities and distinct key nematode species. For that we collected data on soil nematode abundance from published studies that documented the community structure of nematodes exposed to a gradient of water availability in mainland China. Because bacterivorous and fungivorous nematodes grouped in colonizer-persister (cp)-2 guilds are more tolerant to stress (e.g., pollution) than other functional guilds, we selected five abundant and widespread genera as model organisms (Cephalobus, Eucephalobus, Acrobeloides, Aphelenchoides and Aphelenchus). We correlated their relative abundance with soil moisture content and mean annual precipitation to assess their response to drought. Furthermore, we carried out a controlled microcosm experiment to test the influence of drought stress on nematode community structure, identify the winners and losers, and examine the contributing factors including pre-drought abundance, pre-drought body size, generation time, and body size reduction rate. We evaluated the trait-based mechanisms of survival in drought-tolerant species in a petri dish experiment by investigating the survival rate and body size variation of the bacterivore Acrobeloides and the model bacterivore C. elegans across a drought stress gradient.