Hong Qian

Forest et al. (2026; Science , 392: 655−659) evaluated extinction risk for 335,497 angiosperm species worldwide, with the Evolutionarily Distinct and Globally Endangered (EDGE) approach, and identified 9945 EDGE species that disproportionately account for total threatened evolutionary history. Here, we demonstrate that Forest et al.'s results are severely flawed because the phylogenetic trees used by them are not appropriate for determining evolutionary distinctiveness of species and identifying EDGE species.

Despite having only about 670 species worldwide, conifers are one of the ecologically and economically most important plant groups. They have a rich fossil record and previous studies have shown that their current diversity is the result of past radiations, extinction, and dispersal events, restricting many genera to either the Northern or Southern Hemisphere, and concentrating species richness in specific regions. However, it remains poorly explored how this translates into patterns of phylogenetic diversity. In this study, we used a species‐level megaphylogeny and species lists for 391 geographic units worldwide to calculate six metrics of phylogenetic diversity and disparity, and to relate these to climatic factors. We found that the different metrics provided different patterns, reflecting deep and shallow evolutionary history, but that overall southeastern China had the highest values. We also found that patterns of phylogenetic diversity and disparity were better explained by current than historical climate, by temperature‐ than precipitation‐related variables, and by climatic seasonality than by climatic extremes. These patterns differ in many important regards from those known from ferns and angiosperms. Most notably, species‐poor conifer assemblages tend to have high phylogenetic dispersion, being composed of few species belonging to distinct lineages, rather than few lineages with many species each, as is typical for ferns and angiosperms. We conclude that the ecological and evolutionary processes determining community assembly in conifers differ fundamentally from those seen in ferns and angiosperms, reflecting their low global species richness.

Beta diversity is a scalar linking local (alpha) with regional (gamma) species diversity. Understanding patterns of beta diversity is central to ecology and biogeography. It is suggested that beta diversity should be higher for organisms with larger body sizes, which is called the beta diversity−body size hypothesis, because organisms with smaller body sizes are considered to be better dispersers and thus would be expected to have lower rates of species turnover between areas, compared with organisms with larger body sizes. Using a comprehensive database of seed plants in North America, I test this hypothesis. Beta diversity was measured by Simpson’s dissimilarity index. Seed plants were divided into three categories (trees, shrubs and herbs), which represent large, intermediate and small body sizes, respectively. While beta diversity in shrubs is higher than that in herbs, supporting the hypothesis, beta diversity in trees is lower than that in shrubs and herbs, contrary to the hypothesis. These findings hold true regardless of whether North America is considered as a whole or different latitudinal zones are considered separately. Thus, the overall finding of this study only partially supports the hypothesis. This study also shows that in all the three groups of plants, beta diversity decreases with increasing latitude, and is more strongly related with geographic distance than with climatic distance.

Aim: Species composition in biological assemblages is driven by an interplay of evolutionary, environmental, and ecological processes. Investigating the relationships between evolutionary history and climatic conditions can shed light on the variation in biodiversity and phylogenetic structure in biological assemblages. Harnessing a global dataset of ant biodiversity, here we determine the extent to which climate drives geographic patterns of phylogenetic diversity and dispersion in ants. Methods: We calculated mean pairwise distance (MPD, measuring phylogenetic diversity) and the standardized effect size of MPD (MPD _ses , measuring phylogenetic dispersion) in each of over 11,500 ant assemblages, and related them to variables representing current climatic conditions and Quaternary climate change. Location: Global. Time Period: Current. Taxon: Ants. Results: We find that these two metrics are positively correlated with climate averages yet negatively correlated with climate variability. We also find that current climatic conditions are more strongly associated with these phylogenetic metrics than Quaternary climate change. Temperature variables had stronger associations than precipitation variables, and climate extremes and seasonality affected phylogenetic diversity and dispersion equally. Lastly, areas with higher phylogenetic diversity and dispersion tend to have more paleo‐endemic lineages. Main Conclusions: The geographic patterns and climatic associations with ant phylogenetic diversity and dispersion found in this study are largely consistent with those found in butterflies and several plant groups, suggesting that the same mechanisms may have driven phylogenetic structure more broadly across the tree of life.

Conifers have about 670 species worldwide but are one of the ecologically and economically most important plant groups. Their current distributions resulted from the interplay of speciation, dispersal, and extinction, with some major clades restricted to the Northern Hemisphere, whereas others are restricted to the Southern Hemisphere. Here, we explore global geographic patterns of mean diversification rate (MDR), representing recent speciation dynamics, within genera of conifers, and relate MDR to regional species richness and climatic conditions. We find that MDR is negatively correlated with species richness and latitude at a global scale; that latitudinal patterns and relationships of MDR to climatic factors differ between the Northern and Southern Hemispheres; that MDR is correlated positively with mean annual temperature and negatively with annual precipitation; that temperature‐related variables explain less variation in MDR than precipitation‐related variables in the Northern Hemisphere but more variation in the Southern Hemisphere; and that climate extreme variables explain more variation in MDR than climate seasonality variables. These patterns differ in many important aspects from those seen in angiosperms. We hypothesize that small land surface area and the associated paucity of broadly fragmented habitats may limit speciation in the wind‐dispersed conifers, which requires broad spatial separation between diverging populations. Furthermore, conifer diversification peaks in arid habitats, probably related to numerous anatomical, physiological, and life strategy traits. Such differences between conifers and other major groups of land plants allow us to infer generalities of how geographic and climatic drivers and life history traits interact to determine the diversification dynamics of plants.

Background and Aim: Polyploidization is becoming an increasingly important subject in ecology and invasion biology. To date, the role of polyploidy in the success of species invasions remains unclear. Here, we explore the associations between ploidy levels and seed size, reproductive mode, life form, time after introduction and range size of non-native plants introduced to North America, and whether polyploidization is related to invasion success. Methods: Using data on 1804 non-native plant species in continental North America with information on chromosome numbers, we conducted comparative, correlation and regression analyses to investigate the possible links among ploidy level, multiple life-history traits and geographical distribution. Key Results: Among the 1804 species, 54 % were polyploids. The proportion of plants with three or more levels of ploidy was much higher in herbaceous species than in woody species. Species in aquatic, forb and graminoid forms had higher proportions of species that exhibit multiple ploidy levels than trees and shrubs. Range size was also positively related to levels of ploidy. We also observed clear differences in seed size among ploidy levels, but no correlation between chromosome number and seed size. Conclusions: Our findings demonstrate that: (1) polyploidy is linked to other life-history traits at varying degrees or intensities; and (2) the level of ploidy appears to be important in regulating plant traits and distribution. The relationships of levels of ploidy to other traits and range size are useful in predicting species invasiveness and spread potential. Our findings thus have strong implications for invasion biology and management.

Aim: The current distribution of biodiversity is profoundly shaped by evolutionary history. A prevalent pattern of tropical niche conservatism—most lineages originated in warm and humid tropical climates and have conserved those ancestral traits, making their species difficult to adapt to colder and drier temperate climates—has been identified across many major animal and plant groups, offering explanations for global patterns of species richness and phylogenetic structure (including phylogenetic diversity and phylogenetic dispersion). In contrast, based on regional studies, liverworts have been suggested to exhibit a pattern of temperate niche conservatism, but this hypothesis has not been tested globally. Here, we perform a comprehensive global analysis to test this hypothesis. Location: Global. Taxon: Liverworts. Methods: For liverworts in 390 operational geographic units across the world, phylogenetic diversity was measured as mean pairwise distance and phylogenetic dispersion was measured as the standardised effect size of mean pairwise distance. They were related to six variables representing current climatic conditions. Results: We reveal that liverwort phylogenetic diversity is highest in temperate regions with mean annual temperatures approximately ranging from 10°C to 20°C, which holds true across continents and hemispheres. An ancestral state reconstruction recovered a cool ancestral temperature niche for liverworts, estimated at around 13°C. Moreover, while annual precipitation is associated with liverwort phylogenetic diversity more strongly than mean annual temperature, when climatic variables reflecting average, extreme, and seasonality are simultaneously considered, temperature‐related variables emerged as a more significant predictor of liverwort phylogenetic diversity than precipitation‐related variables. Our findings support that liverworts, and by extension to bryophytes, originated under cool and humid climatic conditions. Main Conclusions: We propose that the divergence between bryophytes and tracheophytes was driven by adaptations to distinct climatic environments—tropical for tracheophytes and temperate for bryophytes. The simplified morphology and poikilohydric physiology of bryophytes likely evolved as adaptations to cooler, wetter conditions where water stress is less pronounced than in hot climates.

Liverworts are an important component of terrestrial ecosystems worldwide. They have adapted to and diversified in a wide variety of environments. Investigating variation in net diversification rate is a major goal of biogeographers and ecologists but such investigation is lacking for liverworts at a global scale. Here, we explore global geographic patterns of mean diversification rate (MDR) within genera of liverworts, which are one of the earliest lineages of the extant land plants, and its relationship with latitude, climatic conditions, and regional species richness. We collated species lists of liverworts for each of 390 geographic units (primarily countries, provinces or states) across the world. We related MDR to geographic and current and historical climatic variables, assessed the relative importance of different sets of climatic variables on MDR, and explored the effect of MDR on species richness after accounting for major climatic factors. We analyzed the data with correlation and regression analyses, and structural equation modeling approach. We find that MDR peaks at tropical latitudes and in humid and hot environments, and that at a global scale current climate, temperature-related variables, and climatic seasonality explained more variation in MDR than Quaternary climate change, precipitation-related variables, and climatic extremes, respectively. In addition, we find a positive relationship between MDR and liverwort species richness, with the latter being directly influenced more strongly by climate than by MDR. Most importantly, we find that tropical regions of high liverwort diversity also have high current diversification rates, suggesting ongoing niche occupation. The above-described patterns are similar between the New World and Old World and between the eastern and western parts of the Old World. Our study highlights that tip diversification rates provide a complementary aspect to understand the evolution of liverwort diversity to that recovered by studying phylogenetic diversity and species richness.

There are two major groups of methods estimating diversification rates: One group depends on well resolved phylogenies and the other is phylogeny‐free. Previous studies on angiosperms (flowering plants) have used phylogeny‐based methods to estimate diversification rates and concluded that diversification rates increase with increasing latitudes, a trend opposite to that of liverworts, mosses and ferns, for which diversification rates were estimated with the method‐of‐moments estimator, a nonphylogeny method. In this study, we use the method‐of‐moments estimator to estimate diversification rates of angiosperm species within genera worldwide. We find that diversification rates decrease with increasing latitudes. The result of our study is thus contrary to those of previous studies on angiosperms. We discuss the degree to which these differences are due to methodological limitations of using phylogeny‐based approaches to estimate diversification rates of angiosperms. More data from poorly studied angiosperm groups are needed so that we can move toward developing well‐resolved species‐level phylogenies for angiosperms, which will allow a better assessment of the robustness of various diversification estimation methods.