Yueyao Feng

Studying community assembly has always been a central issue in ecological research and is necessary for understanding mechanisms of species coexistence and biodiversity. Environmental heterogeneity is a driver of biodiversity, but much remains to be learned about how evolutionary processes are affected by environmental factors. We aimed to clarify the evolutionary processes in different vegetation communities in the Huangshan Scenic Area, Anhui Province, China. We constructed a phylogenetic tree of these communities based on a constraint tree and three DNA barcode regions. Community I was characterized by a weakly overdispersed phylogenetic structure for all three plant groups. The structure of Community II showed clustered for total plants and shrubs, overdispersed for trees. However, the phylogenetic structure was clustered for total plants, overdispersed for trees and shrubs in Community III. The main drivers of these patterns were spatial and climatic factors. Phylogenetic α-diversity had a significant positive relationship with species richness. The values of phylogenetic β-diversity reached their maximum at intermediate elevations among three vegetation communities for total plants. The main factors that affected diversity patterns were spatial variables, not climatic factors, indicating that environmental heterogeneity determined the mechanisms of biodiversity and species coexistence in the community. Our results showed that deterministic processes may control community assembly in three different vegetation regions.

Species diversity (SD) and genetic diversity (GD) are the two basic levels of biodiversity. In general, according to the consensus view, the parallel effects of environmental heterogeneity, area, and connectivity on two levels, can drive a positive correlation between GD and SD. Conversely, a negative correlation or no correlation would be expected if these effects are not parallel. Our understanding of the relationships between SD and GD among different ecosystems, sampling methods, species, and under climate change remains incomplete. In the present study, we conducted a hierarchical meta-analysis based on 295 observations from 39 studies and found a positive correlation between genetic diversity and species diversity (95% confidence interval, 7.6–22.64%). However, significant relationships were not found in some ecosystems when we conducted species–genetic diversity correlation analysis based on a single ecosystem. Moreover, the magnitudes of the correlations generally decreased with the number of sampling units and the annual average the temperature of sampling units. Our results highlight the positive correlation between GD and SD, thereby indicating that protecting SD involves protecting GD in conservation practice. Furthermore, our results also suggest that global increases in temperature during the 21st century will have significant impacts on global biodiversity.