Yingbo Yang

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.

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.

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.

Bretschneidera sinensis is an endangered relic tree species in the Akaniaceae family and is sporadically distributed in eastern Asia. As opposed to its current narrow and rare distribution, the fossil pollen of B. sinensis has been found to be frequent and widespread in the Northern Hemisphere during the Late Miocene. B. sinensis is also a typical mycorrhizal plant, and its annual seedlings exhibit high mortality rates in absence of mycorrhizal development. The chromosome-level high-quality genome of B. sinensis will help us to more deeply understand the survival and demographic histories of this relic species. A total of 25.39 Gb HiFi reads and 109.17 Gb Hi-C reads were used to construct the chromosome-level genome of B. sinensis, which is 1.21 Gb in length with the contig N50 of 64.13 Mb and chromosome N50 of 146.54 Mb. The identified transposable elements account for 55.21% of the genome. A total of 45,839 protein-coding genes were predicted in B. sinensis. A lineage-specific whole-genome duplication was detected, and 7,283 lineage-specific expanded gene families with functions related to the specialized endotrophic mycorrhizal adaptation were identified. The historical effective population size (N_e) of B. sinensis was found to oscillate greatly in response to Quaternary climatic changes. The N_e of B. sinensis has decreased rapidly in the recent past, making its extant N_e extremely lower. Our additional evolutionary genomic analyses suggested that the developed mycorrhizal adaption might have been repeatedly disrupted by environmental changes caused by Quaternary climatic oscillations. The environmental changes and an already decreased population size during the Holocene may have led to the current rarity of B. sinensis. This is a detailed report of the genome sequences for the family Akaniaceae distributed in evergreen forests in eastern Asia. Such a high-quality genomic resource may provide critical clues for comparative genomics studies of this family in the future.

The increase in species number from poles to the equator is one of the most fundamental patterns in ecology. Although several hypotheses have been proposed, there is a lack of consensus on the mechanisms underlying this pattern. While most hypotheses provide plausible explanation for high tropical diversity of tropical clades, it is unclear if similar mechanisms drive the diversity of extra‐tropical clades. Here, we investigated the environmental drivers influencing the diversity pattern of a Mediterranean plant genus Medicago and dissect their effects across continents and biomes. We compiled a comprehensive dataset on the distribution of all Medicago species and mapped their distribution at the spatial resolution of 100 × 100 km ² . We used generalized linear models to quantify the relative effects of environmental factors on the richness patterns of Medicago and its two life forms. Next, using geographically weighted regression, we explored the variation in richness–environment relationship across latitude. We found that Quaternary climate change and environmental energy were important explanatory variables, and their effects were consistent at global, continental and biome scales. However, we found contrasting effect of environmental energy in temperate and tropical regions, with species richness increasing with energy in the temperate and decreasing in the tropics. We also found strong affinity of Medicago species to its ancestral Mediterranean climatic niche. Our results suggest that the spatial variation in Medicago richness patterns may be strongly influenced by heat tolerance as opposed to the tropical clades that depend upon cold tolerance. This dependency on heat tolerance can be attributed to strong niche conservatism exhibited by Medicago species. Our findings provide new insights into the richness‐energy hypothesis and suggest that high environmental energy may not necessarily yield high species diversity but may also lower species diversity, especially of extra‐tropical clades towards the tropics.