Patterns and drivers of beta diversity of Asteraceae across Africa: A taxonomic and phylogenetic approach

Abstract

Unravelling the spatial and temporal dynamics of biodiversity is a central goal in ecology and evolutionary biology, requiring an integration of taxonomic and phylogenetic beta-diversity. However, a lack of comprehensive studies at continental scales for major ecologically diverse plant groups hinders both fundamental biogeographical research and effective conservation planning. Using a curated and consolidated dataset of 6439 taxa of Asteraceae across 68 African botanical countries, we assess the geographic patterns and determinants of the taxonomic and phylogenetic beta-diversity of across Africa. Both taxonomic and phylogenetic beta-diversity vary considerably across the continent, with the lowest values concentrated in moist tropical regions. On average, total taxonomic beta-diversity is higher than phylogenetic beta-diversity, whereas the opposite is true for the nestedness component. Both facets are predominantly driven by species turnover rather than nestedness. Local neighbourhood analyses using a moving window approach reveal that environmental variations in taxonomic and beta-diversity are primarily driven by temperature seasonality and annual mean temperature. At the continental scale, multiple regression on distance matrices (MRM) show that geographical distance explains the largest share of variation in both diversity facets, followed by paleoclimatic distance. These findings suggest that dispersal limitation plays a greater role than environmental filtering in shaping African Asteraceae assemblages. By integrating taxonomic and evolutionary histories, this study advances our understanding of plant community assembly in Africa and highlights the critical need for multifaceted approaches to conservation planning.