Geographic patterns and climatic drivers of the mean genus age of liverworts in North America

Phylogenetic niche conservatism posits that species tend to retain ancestral ecological traits and distributions,which has been broadly tested for lineages originating in tropical climates but has been rarely tested for lineages that originated and diversified in temperate climates.Liverworts are thought to originate in temperate climates.Mean lineage age reflects evolutionary history of biological communities.Here,using regional liverwort floras across a long latitudinal gradient from tropical to arctic climates in North America,we test the age-component of the temperate niche conservatism hypothesis.Mean genus age(MGA)was estimated for each of 76 regional floras of liverworts.We related MGA to climatic variables for North America as a whole and for its eastern and western parts separately,and used variation partitioning analysis to assess the relative importance of temperature-versus precipitationrelated variables and of climate extremes versus seasonality on MGA.We found that older genera of liverworts tend to concentrate in humid regions of intermediate temperatures in the range of 10℃-20℃,from which liverworts have adapted to and diversified into more arid,colder,and hotter regions,supporting the temperate niche conservatism hypothesis.We also found that across North America the MGA of liverwort assemblages is more strongly affected by precipitation-related variables than by temperature-related variables,and is more strongly affected by climate extremes than by climate seasonality.Geographic patterns of the MGA of liverworts are consistent with the temperate niche conservatism hypothesis,rather than the tropical niche conservatism hypothesis,the latter of which is broadly supported by angiosperms.

Global patterns and ecological drivers of taxonomic and phylogenetic endemism in angiosperm genera

Endemism of lineages lies at the core of understanding variation in community composition among geographic regions because it reflects how speciation,extinction,and dispersal have influenced current distributions.Here,we investigated geographic patterns and ecological drivers of taxonomic and phylogenetic endemism of angiosperm genera across the world.We identify centers of paleo-endemism and neo-endemism of angiosperm genera,and show that they are mostly located in the Southern Hemisphere in tropical and subtropical regions,particularly in Asia and Australia.Different categories of phylogenetic endemism centers can be differentiated using current climate conditions.Current climate,historical climate change,and geographic variables together explained~80%of global variation in taxonomic and phylogenetic endemism,while 42-46%,1%,and 15%were independently explained by these three types of variables,respectively.Thus our findings show that past climate change,current climate,and geography act together in shaping endemism,which are consistent with the findings of previous studies that higher temperature and topographic heterogeneity promote endemism.Our study showed that many centers of phylogenetic endemism of angiosperms,including regions in Amazonia,Venezuela,and west-central tropical Africa that have not previously been identified as biodiversity hotspots,are missed by taxon-based measures of endemism,indicating the importance of including evolutionary history in biodiversity assessment.

Forest characteristics and population structure of Glyptostrobus pensilis, a globally endangered relict species of southeastern China

The Chinese water pine Glyptostrobus pensilis is the sole surviving species of the genus Glyptostrobus. It is endemic to southern China, central Vietnam, and eastern Laos, and today it is nearly extinct in the wild. Forest community characteristics and population structure of G. pensilis in China have remained un-known up to now. We investigated six swamp forest stands and analyzed their forest community characteristics (i.e. vertical stratification, species composition, and diversity) and population structure, including the frequency distribution of DBH (diameter at breast height) and age-classes as found in Fujian Province, southeastern China. The vertical stratifications of all the forest stands were rather simple. The remaining wild specimens ranged from roughly 15 to some 357 years for an average of ca. 85 years, with only a few individuals less than 20 years old. Compared with the stands and populations of G. pensilis in Vietnam, the taxonomic compositions of the stands in the two regions were different, except for the dominant species-G. pensilis. The Shannon-Wiener index showed the overstory of each stand had much lower diversity (0.26 on average) in Fujian Province than that (1.97 on average) in Vietnam, whereas the diversity indices were about the same (around 2.41) for the understories in the two regions. Furthermore, we discovered 18 G. pensilis seedlings at the study sites in Fujian Province. This discovery demonstrates that G. pensilis regeneration is extremely poor and its populations are declining, although these populations are rela-tively healthier than those in Vietnam.

Geographic patterns of taxonomic and phylogenetic β-diversity of angiosperm genera in regional floras across the world

Beta diversity(β-diversity)is the scalar between local(α)and regional(γ)diversity.Understanding geographic patterns ofβ-diversity is central to ecology,biogeography,and conservation biology.A full understanding of the origin and maintenance of geographic patterns ofβ-diversity requires exploring both taxonomic and phylogeneticβ-diversity,as well as their respective turnover and nestedness components,and exploring phylogenetic p-diversity at different evolutionary depths.In this study,we explore and map geographic patterns ofβ-diversity for angiosperm genera in regional floras across the world.We examine both taxonomic and phylogeneticβ-diversity and their constituent components,and both tip-weighted and basal-weighted phylogeneticβ-diversity,and relate them to latitude.On the one hand,our study found that the global distribution ofβ-diversity is highly heterogeneous.This is the case for both taxonomic and phylogeneticβ-diversity,and for both tip-weighted and basal-weighted phylogeneticβ-diversity.On the other hand,our study found that there are highly consistent geographic patterns among different metrics ofβ-diversity.In most cases,metrics ofβ-diversity are negatively associated with latitude,particularly in the Northern Hemisphere.Different metrics of taxonomicβ-diversity are strongly and positively correlated with their counterparts of phylogeneticβ-diversity.

中国佛教寺庙植物多样性和佛教树种替代

佛教是我国的主要宗教之一,佛教寺庙作为佛教文化的物质载体,对区域生物多样性的保护具有重要意义。本研究收集了中国191座寺庙的树种名录,分析了不同地区寺庙的树种组成、分布格局及影响因素,以明确寺庙在生物多样性保护中的作用。结果表明:(1)全国191座寺庙共收集到树种1,059种,隶属116科410属,大多数树种(773种)仅出现在1–2座寺庙中;(2)寺庙树种中含有大量乡土植物,并且保存了丰富的受威胁树种(94种),具有较高的生物多样性保护价值;(3)不同气候带的佛教树种组成差异较大,主要受气候因子限制;(4)佛教树种具有清晰的树种替代现象,由南向北原始佛教树种逐渐由形态相似的本土物种(替代佛教树种)替代。以上结果表明中国寺庙中保存了非常丰富的植物资源,有效地保护和利用寺庙植物资源对维持区域生物多样性和提升城市绿化水平具有积极作用。