•Karst endemic plants exhibit profound genetic vulnerability driven by historical and anthropogenic factors.•Whole-genome duplication (WGD) and gene family dynamics are key adaptive mechanisms for karst plant survival.•Genomic data enable precision conservation strategies for endangered karst plants.
The species pool hypothesis argues that local species diversity mainly depends on regional diversity, which is influenced by dispersal, historical and current environmental conditions. We hypothesize that regional factors, such as the size of the regional species pool, current climate, topographical variability, and historical climate stability, also impact local species-abundance patterns, like the rarity of local species, though their specific effects are not yet well understood. Analyzing data from 3307 species across 3923 forest plots in Chinese subtropical and tropical regions, we employed boosted regression trees and structural equation modeling to assess the roles of regional species pool size along with climatic seasonality, topography, and soil factors, in shaping local richness and rarity. We found that local tree species richness declined with increasing latitude, while species rarity decreased from west to east. The factors such as current regional environment, paleoclimate stability, and human disturbance significantly affected local richness and rarity, primarily through their effects on regional species pool size. The impacts of regional mean temperature and elevational range on local richness surpassed local influences. Conversely, local climatic seasonality exerted the strongest influence on species rarity, followed by human activity. Overall, the findings indicate that regions with large regional species pools tend to support diverse communities with high proportions of rare species.
Orchid diversity and conservation are tightly linked to the evolution of orchid lifeforms (e.g., epiphytic or terrestrial) as epiphytic species are highly sensitive to environmental changes and includes super-high species diversity. However, the factors that drive the evolution of orchid lifeform remain unclear. Here, we used a global orchid phylogeny (2272 species, all five subfamilies and 302 genera) to evaluate the relative contributions of potential factors (i.e., phylogeny, climate region, pollination traits) that may drive orchid lifeform evolution using partial R2 framework. Conventional correlation results indicated that orchid lifeforms are strongly associated with climate regions and weakly related to pollination traits. In contrast, partial R2 analyses revealed that orchid phylogeny alone accounted for 62% of lifeform variation; pollinator attraction strategies independently explained an additional 23.9% variation, while climate region only further explained 3.4%. The discrepancies arise from variation in phylogenetic conservatism of different orchid traits: both orchid lifeform and climate region are more phylogenetically conserved than pollination traits. Specifically, our findings that species evolution plays a key role in lifeform evolution together with variation in phylogenetic conservatism among key traits provide insights into trait evolution and species conservation in orchids.
Bignoniaceae, a pantropical family comprising 79 genera and 901 species, exhibits remarkable morphological and ecological diversity, including lianas, shrubs, trees, and high-elevation herbs. Reconstructing the early evolutionary history of Bignoniaceae has been particularly challenging due to ancient hybridization/introgression and incomplete lineage sorting (ILS). In this study, we re-evaluated the deep branching relationships within Bignoniaceae using phylogenomic data from 1275 single/low-copy nuclear genes and the Angiosperms353 dataset, complemented with chloroplast genomes and quantified the roles of hybridization, and ILS in shaping the family’s evolutionary history. Our results robustly resolved Bignoniaceae into ten major clades, with the Argylia clade sister to a clade containing Oroxyleae, the Delostoma clade, Catalpeae, Bignonieae, the Tabebuia alliance, and the Paleotropical clade, while the Delostoma clade and Catalpeae formed a monophyletic lineage. Divergence time estimation revealed a rapid diversification during the early Eocene, coinciding with the Early Eocene Climatic Optimum. Several lines of evidence indicate that the predominant factor underlying phylogenetic conflicts across deep nodes is ILS. Introgression/hybridization also contributed significantly, with at least three ancient events detected: between Tourrettieae and the Delostoma clade, between the Delostoma clade and Bignonieae, and a major introgression from the Argylia clade to the Oroxyleae-Delostoma-Catalpeae-Bignonieae-Tabebuia-Paleotropical clade. This study provides a robust phylogenetic foundation and comprehensive evolutionary synthesis for Bignoniaceae, shedding new light on its early diversification.
•Humboldtia, is a scientifically valuable yet underexplored endemic genus from the Western Ghats - Sri Lanka Biodiversity hotspot.•Comprising just eight species, all of which are under threat of extinction, the genus is one of the evolutionarily unique plant lineages within the region's flora.•The genus shows ecological adaptations, such as domatia-mediated ant-plant symbiosis and cauliflorous flowering, which are important in its natural habitat.•Humboldtia is an exceptional model for investigating speciation dynamics, biogeographical diversification, and ecological specialisation in tropical forest ecosystems.•However, the genus remains poorly studied and inadequately protected, calling for increased attention in both research and conservation efforts.
