Spatial and phylogenetic structure of Alpine stonefly community assemblages across seven habitats using DNA-species

Abstract

AbstractStream ecosystems are spatially heterogeneous, with many different habitat patches distributed within a small area. The influence of this heterogeneity on the biodiversity of benthic insect communities is well documented; however, studies of the role of habitat heterogeneity in species coexistence and community assembly remain limited. Here, we investigated how habitat heterogeneity influences spatial structure (beta biodiversity) and phylogenetic structure (evolutionary processes) of benthic stonefly (Plecoptera, Insecta) communities.We sampled 20 sites along two Alpine rivers, including seven habitats in four different reaches (headwaters, meandering, bar-braided floodplain, and lowland spring-fed). We identified 21 morphological species and delineated 52 DNA-species based on sequences from mitochondrial cox1 and nuclear ITS markers. Using DNA-species, we first analysed the patterns of variation in richness, diversity, and community composition by quantifing the contribution of each of the four reaches and seven habitats to the overall DNA-species diversity using an additive partition of species diversity analysis and distance-based redundancy analysis. Using gene-tree phylogenies, we assessed whether environmental filtering led to the co-occurrence of DNA-species using a two-step analysis to find a phylogenetic signal.The four reaches significantly contributed to DNA-species richness; with the meandering section having the highest contribution. However, we found that habitats had an effect on DNA-species diversity, where glide, riffle and, pool influenced the spatial structure of stonefly communities possibly due to a high species turnover.Among the habitats, the pool showed significant phylogenetic clustering, suggesting high levels of evolutionary adaptation and strong habitat filtering. This community structure may be caused by long-term stability of the habitat and the similar requirements for co-occurring species.Our study shows the importance of different habitats on the spatial and phylogenetic structure of stonefly community assemblies and sheds light on the habitat-specific diversity that may help improve conservation practices.