Regional and global elevational patterns of microbial species richness and evenness

Wang, JianjunMeyer, SandraSoininen, JanneCasamayor, Emilio O.Pan, FeiyanTang, XiangmingYang, XiangdongYunlin, ZhangWu, QinglongZhou, JizhongShen, Ji.  Ecography 39: 1-10 (2016) DIGITAL.CSIC

Although elevational gradients in microbial biodiversity have attracted increasing attention recently, the generality in the patterns and underlying mechanisms are still poorly resolved. Further, previous studies focused mostly on species richness, while left understudied evenness, another important aspect of biodiversity. Here, we studied the elevational patterns in species richness and evenness of stream biofi lm bacteria and diatoms in six mountains in Asia and Europe. We also reviewed published results for elevational richness patterns for soil and stream microbes in a literature analysis. Our results revealed that even within the same ecosystem type (that is, stream) or geographical region, bacteria and diatoms showed contrasting patterns in diversity. Stream microbes, including present stream data, tend to show signifi cantly increasing or decreasing elevational patterns in richness, contrasting the fi ndings for soil microbes that typically showed nonsignifi cant or signifi cantly decreasing patterns. In all six mountains for bacteria and in four mountains for diatoms, species richness and evenness were positively correlated. Th e variation in bacteria and diatom richness and evenness were substantially explained by anthropogenic driven factors, such as total phosphorus (TP). However, diatom richness and evenness were also related to diff erent main drivers as richness was mostly related to pH, while evenness was most explained by TP. Our results highlight the lack of consistent elevational biodiversity patterns of microbes and further indicate that the two facets of biodiversity may respond diff erently to environmental gradients.