Tropical Niche Conservatism and Dispersal Limitation Jointly Determine Taxonomic and Phylogenetic β-Diversities of Odonata in Eastern China

Aim

Tropical niche conservatism (TNC) and dispersal limitation (DL) are major ecological and evolutionary mechanisms in shaping taxonomic and phylogenetic β-diversities. While these mechanisms have been studied in plants and vertebrates, their roles in freshwater taxa remain unclear. We leveraged Odonata species distribution and phylogenetic data to map geographical patterns of taxonomic and phylogenetic β-diversities, and to determine whether Odonata β-diversity is primarily shaped by TNC or DL and whether temperature seasonality is a key driver determining TNC.

Location

Eastern China.

Time Period

Present.

Major Taxa Studied

Odonata.

Methods

A moving window containing nine grids of 50 × 50 km was employed to quantify taxonomic and phylogenetic β-diversities, including their turnover and nestedness components. A null model was utilised to calculate randomly expected phylogenetic β-diversity based on observed taxonomic β-diversity and site-specific regional species pools. The generalised dissimilarity model was used to assess the roles of climatic and geographic distances shaping β-diversity and to identify the key climatic factors.

Results

Taxonomic total β-diversity and its turnover component were generally higher than phylogenetic β-diversity in most Odonata communities, with phylogenetic β-diversity being relatively higher mainly in tropical regions. Current climatic factors independently explained slightly more of the variation in total β-diversity than geographic distance alone, while geographic distance independently explained slightly greater proportions of deviance in turnover components. However, their joint effects accounted for an even larger part of the variation in β-diversity. The key climatic predictors were temperature seasonality.

Main Conclusions

Current climatic factors, particularly temperature seasonality, largely shape taxonomic and phylogenetic β-diversities of Odonata communities. Spatial turnover along the climatic gradient tends to involve phylogenetically related taxa, resulting in overall higher taxonomic than phylogenetic β-diversity, supporting the TNC. The joint effects of climatic and geographic distances highlight the roles of climate, interacting with topographic complexity, shaping taxonomic and phylogenetic β-diversities of Odonata in eastern China.