The phylogenetic tree and functional dendrogram of Chinese Rhododendron species

Data processing methods and steps:A phylogeny of 442 Rhododendron species (73.3%) native to China was derived from the plastome phylogenetic tree of this genus, which included 588 species (including 21 subspecies) constructed based on plastome sequences by Mo et al. (unpublished data). To incorporate species lacking plastome sequences, we used a taxonomic similarity substitution approach, following the species description and classification system employed in FOC and/or the genus Rhododendron of China (Geng, 2014). Specifically, 137 species were inserted as polytomies with their morphologically closest relatives within the same subsection or section. Additionally, the remaining 24 species, which lacked clear morphological affinities or molecular data, were randomly inserted within their respective subsection or section in polytomies.To quantify the functional diversity of Rhododendron species in China, we collected seven key traits for each species: life form (evergreen or deciduous), plant height, leaf length, leaf width, leaf texture (leathery, papery or membranous), number of flowers per inflorescence, and corolla length. These functional traits were compiled from FOC, the genus Rhododendron of China, and other relevant literature (see Table S1). For continuous traits, we utilized the maximum recorded value for each species. Based on these traits, we computed Gower’s distance matrix to quantify pairwise functional dissimilarity among the species (Pavoine et al., 2009). Subsequently, we constructed a functional dendrogram using hierarchical clustering with the unweighted pair group method with arithmetic mean (Wang et al., 2023).To investigate the relative contributions of environmental factors to the spatial patterns of Rhododendron diversity in China, we selected 18 environmental variables commonly used in macroecological studies. These variables were classified into six categories: energy, water, climatic seasonality, heterogeneity, human influence, and historical climate, representing contemporary climate conditions, habitat characteristics, human activities, and climatic stability since the Last Glacial Maximum.The detailed calculation methods for the diversity indices can be found in the Methods.Data description: The phylogenetic tree and functional dendrogram of Chinese Rhododendron species, a table of 18 environmental variables and 13 diversity metrics.