Nawal Shrestha

Aim: Although studies have linked mountain radiations to clade diversification rates, it is unclear whether or why these radiations differ between tropical and temperate mountains. Here, we investigated differences in species richness, climatic niche space, lineage accumulation, and diversification rates of a widespread montane shrub between tropical and temperate mountains, and explored the ecological and evolutionary factors that contribute to these disparities. Location: Global. Taxon: Gaultheria (Ericaceae), represented by 292 species. Methods: We built a comprehensive global distribution dataset of the genus and combined it with a dated molecular phylogeny to assess species diversity, climatic niche space, and diversification rates across tropical and temperate mountains. We evaluated the contributions of environmental heterogeneity, climate stability, and other ecological factors to the observed diversity patterns. Results: The extant diversity of Gaultheria is significantly higher in tropical than in temperate mountains. The variables representing habitat heterogeneity and climate stability were the best predictors of species richness. Niche diversity was significantly higher in tropical mountains, while diversification rate analyses revealed no significant differences between tropical and temperate lineages. Main Conclusions: Our findings provide empirical evidence that higher species richness in tropical mountains is associated with broader climatic niches, greater environmental heterogeneity, and long‐term species persistence rather than elevated diversification rates. These findings provide an improved understanding of the mechanisms shaping the exceptional biodiversity in tropical montane ecosystems and highlight the interplay of ecological and evolutionary processes in shaping regional differences in species richness.

Magnoliaceae, a typical boreotropical relict lineage, shows striking species richness in tropical regions, making it an important model for testing the time‐for‐speciation and diversification rate hypotheses for present‐day diversity patterns. Here, we reconstructed a time‐calibrated phylogeny using plastomes from 123 species, representing Liriodendron and all 15 sections of Magnolia , and investigated its colonization and diversification history. Our results reveal that Magnoliaceae likely experienced peak extinction during the mid‐Eocene, accompanied by a range contraction from high latitudes to the amphi‐Pacific tropics, followed by the rise of tropical clades with rapid diversification. Phylogenetic generalized least squares analysis demonstrates that diversification rate explains clade‐level diversity variation more strongly than time for speciation. Tropical regions, such as South America and Southeast Asia, with high Magnoliaceae diversity consistently show elevated diversification rates and shorter time for speciation. These results indicate that higher diversification rate, rather than longer time for speciation, explains the high diversity of Magnoliaceae in tropical clades and regions. Our findings not only shed light on the evolutionary history of Magnoliaceae but also provide important insights into the broader processes that shape tropical biodiversity.

Summary: This study examines the climatic niche dynamics of naturalized plants in China, emphasizing how incomplete species distribution data from digitized herbarium specimens and associated observation records accessible through global data portals (e.g. the Global Biodiversity Information Facility, GBIF) influence the estimation of niche sizes and shifts during species migration and naturalization. We compared the climatic niche sizes and shifts of naturalized plants using two datasets: one based solely on GBIF and the other integrating digitally available records retrieved from local Chinese sources. We also analyzed niche mismatches to predict ecological niche changes and assess their relationship with climatic adaptability. The integration of locally mobilized digital datasets significantly improved niche size estimates and revealed more pronounced niche shifts than inferred from GBIF data alone. These shifts were mainly driven by temperature and seasonality gradients. The use of GBIF‐only data underestimated the climatic space occupied by naturalized plants, particularly in southern China. Our findings highlight the need for global data providers to integrate, whenever possible, local biodiversity records to better understand the climatic resilience and expansion potential of naturalized species. Such integration is crucial for accurately predicting their future distributions and ecological impacts in new environments.

Plants with restricted distributions and small population sizes are particularly vulnerable to climate change. Sesamum species are ideal for species distribution modeling due to their ecological sensitivity, agricultural and economic importance, and wide geographic range, providing insights for conservation and policy. We applied the maximum entropy (MaxEnt) model to assess the global ecological niche breadth of Sesamum species and examine how bioclimatic and soil variables influence their future (2080) distribution. We identified key environmental drivers and projected species‐specific range shifts under changing climatic conditions. MaxEnt models effectively predicted suitable habitats, with climate variables playing a dominant role. Precipitation of the wettest month (BIO13) was particularly influential for S. abbreviatum, S. alatum, and S. angustifolium, while temperature variables (BIO7, BIO11) were also key. Elevation moderately impacted S. angolense, while soil factors such as pH (S. abbreviatum) and clay content (S. angolense) exhibited species‐specific effects. Principal component analysis revealed variation in niche breadth, with S. indicum and S. schinzianum occupying broader ecological ranges, whereas S. saxicola and S. abbreviatum were more restricted. Future projections suggest 46.4% of the species will experience range contractions, with S. schinzianum facing the most significant decline. Conversely, 39.3% of the species, including S. imperatricis and S. abbreviatum, are expected to expand their ranges. Phylogenetic analyses indicate a random distribution of niche breadth and extinction risk across the genus. Our findings highlight the susceptibility of Sesamum species to climate change, emphasizing the need for urgent conservation actions. Prioritizing vulnerable species such as S. forbesii and S. sesamoides, alongside habitat restoration and long‐term monitoring, is crucial to mitigate population declines and prevent extinction.

Over the past half century, international trade and exchange have continued to increase in China, resulting in the widespread introduction of alien plant species. The accumulation of these alien species has accelerated invasion events, posing serious threats to local ecological security and economic development. Comprehensive and accurate species distribution records are extremely important for early detection, understanding dispersal dynamics, and supporting various management strategies and research initiatives. However, biodiversity databases, both global and local, often lack comprehensive and high‐resolution distribution data for alien invasive plant species (AIPs). This limitation is particularly evident in China, where local databases typically provide coarse spatial data, often restricted to the provincial level, leading to a substantial underestimation of the actual distribution of AIPs. Here, we fill this gap by creating the most comprehensive distribution database for AIPs in China at a much finer spatial resolution. By integrating 73,469 distribution records from China's online herbarium, biodiversity databases, flora, published literature, and 173,396 georeferenced records from GBIF, we built the county‐level distribution database for 400 AIPs and report for the first time their presence in 2684 administrative counties in China (92.5% of the total counties). Notably, our database provides 2.58 times more distribution records than global biodiversity data repositories such as GBIF and also includes the earliest introduction dates for each AIP. The temporal range of the records spans from 1607 to 2023, capturing over 400 years of AIP presence in China. These rigorously quality‐controlled georeferenced data can be used to examine the dynamics and influencing factors of plant invasions in China. They can also serve as the most updated data reference for policy makers in designing effective AIP management policies in China. We encourage users to cite this data paper when utilizing the data, and there are no restrictions on its use for non‐commercial purposes.

Premise: Plants, particularly those with limited distribution ranges and small population sizes, are expected to be severely impacted by changing climatic conditions. Sesamum species are ideal for Species Distribution Modeling (SDM) in the context of climate change due to their narrow distribution ranges, agricultural and economic significance, sensitivity and adaptability to environmental conditions, wide geographic range, and potential to inform policy and adaptation strategies Methods: We used Maximum Entropy (MaxEnt) Model to quantify global ecological niche breadth of species in the genus Sesamum and to assess how bioclimatic and soil heterogeneity indices impact the future (to the year 2080) suitable distribution ranges of the genus Sesamum. We also quantified which environmental variables contribute most to driving the patterns and suitable geographical ranges for Sesamum. Results: Maxent models accurately predicted suitable habitats for Sesamum species. Precipitation patterns, especially seasonal extremes, were key determinants of species distribution. Temperature also influenced habitat suitability, with specific requirements varying among species. These findings highlight the complex interplay between climate and edaphic factors in shaping species distributions. Species with broader niches have larger geographic ranges. However, future climate change is predicted to reduce niche breadths for most species (74%), with some facing substantial range contractions. In contrast, a few species (11%) are projected to expand their ranges, while other species (15%) will experience negligible impacts. Phylogenetic analysis did not reveal significant patterns in extinction risk and niche breadth evolution. Conclusion: This study highlights the vulnerability of Sesamum species to climate change, with projected reductions in range sizes necessitating urgent conservation efforts. Prioritizing species such as S. forbesii and S. sesamoides, alongside targeted actions such as habitat restoration and long-term monitoring, is crucial to prevent population decline and potential extinction.