Plant Diversity最新文献

Understanding plant diversity within geographical ranges and identifying key species that drive community variation can provide crucial insights for the management of grasslands. However, the contribution of both local sites and plant species to beta diversity in grassland ecosystems has yet to be accurately assessed. This study applied the ecological uniqueness approach to examine both local contributions to beta diversity (LCBD) and species contributions to beta diversity (SCBD) across six major geographical ranges in alpine grasslands. We found that LCBD was driven by species turnover, with climate, plant communities, and their interactions influencing LCBD across spatial scales. LCBD values were high in areas with low evapotranspiration, high rainfall variability, and low species and functional richness. Precipitation seasonality predicted large-scale LCBD dynamics, while plant community abundance explained local LCBD variation. In addition, we found that SCBD were confined to species with moderate occupancy, although these species contributed less to plant biological traits. Our findings are crucial for understanding how ecological characteristics influence plant beta diversity in grasslands and how it responds to environmental and community factors. In addition, these findings have successfully identified key sites and priority plants for conservation, indicating that using standardized quadrats can support the assessment of the ecological uniqueness in grassland ecosystems. We hope these insights will inform the development of conservation strategies, thereby supporting regional plant diversity and resisting vegetation homogenization.

Subgenus Melanocrommyum is the second largest subgenus of Allium, with a wide distribution ranging from the Canary Islands to northwestern India. This study investigates the phylogeny, biogeographic patterns, and morphological character evolution of the subgenus using 117 accessions representing 107 taxa across the 19 currently recognized sections within Allium subgenus Melanocrommyum. Although the subgenus is monophyletic, significant incongruence exists between morphological and molecular data. Our plastome-based phylogenetic analysis identified five distinct lineages (A-E), corresponding to the geographic distributions of the species. However, plastome lineages (A-E) and ITS clusters (A-G) were incongruent. Biogeographic and molecular dating analyses suggest that Melanocrommyum evolved in association with tectonic uplift events in Central Asia during the Late Miocene or Oligocene. Our finding that Melanocrommyum plastomes have lost infA and one copy rps19 gene indicate that the subgenus has undergone a relatively recent diversification. We also found that narrow leaves and fasciculate to semi-globose inflorescences may represent ancestral traits within the subgenus. This study provides new insights into the biogeographic history and trait evolution of Melanocrommyum, suggesting recent diversification influenced by tectonic events and climate change, while highlighting the complexity of molecular and morphological data integration.

Invasive alien plant species (IAPS) pose severe threats to global biodiversity conservation. Effective management of IAPS requires mapping their distribution and identifying the environmental factors that drive their spread. The Gaoligong Mountains, a renowned biodiversity hotspot in southwestern China, currently face the dual challenges of IAPS invasion and climate change. However, we know little about the distribution patterns, key environmental drivers, and sensitivity of IAPS to future climate change in this region. In this study, we mapped IAPS richness distribution and identified invasion hotspots throughout the Gaoligong Mountains. In addition, we assessed the relative importance of environmental variables in shaping the spatial distribution of IAPS richness and projected potential shifts in IAPS richness under various climate change scenarios. We identified 161 IAPS, primarily concentrated in the low-elevation tropical and subtropical regions along river valleys, forming belt-like invasion hotspots. The key factors shaping IAPS richness included disturbance complexity, elevation, seasonal precipitation, and vegetation types. Notably, IAPS richness significantly declined with increasing elevation and latitude but increased with higher disturbance complexity. Moreover, IAPS were more prevalent in grasslands and shrublands than in forested areas. Ensemble modeling of future climate scenarios predicted that the distribution of IAPS richness would shift to progressively higher elevations. These findings provide valuable insights for managing IAPS in mountainous regions that play a crucial role in global biodiversity conservation.

As climate change triggers unprecedented ecological shifts, it becomes imperative to understand the genetic underpinnings of species' adaptability. Adaptive introgression significantly contributes to organismal adaptation to new environments by introducing genetic variation across species boundaries. However, despite growing recognition of its importance, the extent to which adaptive introgression has shaped the evolutionary history of closely related species remains poorly understood. Here we employed population genetic analyses of high-throughput sequencing data to investigate the interplay between genetic introgression and local adaptation in three species of spruce trees in the genus Picea (P. asperata, P. crassifolia, and P. meyeri). We find distinct genetic differentiation among these species, despite a substantial gene flow. Crucially, we find bidirectional adaptive introgression between allopatrically distributed species pairs and unearthed dozens of genes linked to stress resilience and flowering time. These candidate genes most likely have promoted adaptability of these spruces to historical environmental changes and may enhance their survival and resilience to future climate changes. Our findings highlight that adaptive introgression could be prevalent and bidirectional in a topographically complex area, and this could have contributed to rich genetic variation and diverse habitat usage by tree species.

The formation of pantropical intercontinental disjunction (PID) in plants has generally been attributed to vicariance, boreotropical migration, and long-distance dispersal. However, this pattern has primarily been examined in herbs, shrubs, and trees, and less commonly studied in interlayer plant taxa. Here we examined evolutionary processes that resulted in the PID of a pantropical woody liana, Uncaria (Rubiaceae). We first constructed a comprehensive phylogeny by employing 73 plastid protein-coding sequences from 29 accessions of Uncaria (including 16 newly sequenced) from different continents. We then inferred divergence time, history and ecological niche evolution of this genus. Our results showed that Uncaria consisted of four well-supported clades that belonged to two geographically distinct lineages: the Asia-Oceania lineage and the Afro-Neotropical lineage. Biogeographic reconstruction showed this genus likely originated in Asia during the early Miocene (ca. 19.03 Ma) and the Middle Miocene Climatic Optimum may have triggered the early diversification of Uncaria. Due to its recent origin and small seeds with long wings, wind or water-mediated long-distance dispersal may have contributed to the distribution of Uncaria in tropical Oceania (via stepping-stone dispersal) and tropical Africa and America (by transoceanic dispersal). Our findings also indicate that diversification of Uncaria was primarily driven by ecological niche divergence, particularly climatic factors. Our study emphasizes the dual role of climatic niche divergence and long-distance dispersal in shaping the PID of Uncaria, providing references for many other extant lineages with similar distributions.

In forests, a few large trees (L-trees) versus small-medium trees (S-trees) are often considered the major reservoir of aboveground carbon stock (AGCS). Here, we hypothesize that tree species' functional strategies regulate AGCS by tree sizes in temperate deciduous forests across local scale environmental gradients. Using data from 99 plots, we modelled the multivariate effects of the tree-based (tree diversity, stand density and multidimensional tree size inequality) versus the trait-based (multi-trait diversity and single-trait dominance) attributes of L-trees versus S-trees, along topographic and soil conditions, to predict AGCS through four L-trees threshold size (i.e., ≥ 50 cm fixed-diameter, top 95th percentile, ≥ top 50% cumulative AGCS descending-ranked ordered, and mean threshold size) approaches. The tree-based and trait-based attributes of L-trees and S-trees shaped species co-occurrence processes but L-trees regulated AGCS more effectively (31.29-93.20%) than S-trees and abiotic factors across four thereshold size approaches and two concepts. Although L-trees threshold size and tree-based attributes mattered for AGCS, the dominant resource-acquisitive strategy of structurally complex L-trees having higher specific leaf area but lower leaf dry matter content and lesser multi-trait dispersion could promote AGCS better than the resource-conservative strategy (low specific leaf area) of S-trees. Capturing tree species' functional strategies, synergies and trade-offs across tree sizes can enhance our understanding of how to achieve nature-based carbon neutrality and lessen climate change. Thus, forest management and restoration initiatives should prioritize high-functioning tree species with dominant productive traits while conserving multi-trait diversified species in temperate deciduous forests.

Deep genome skimming (DGS) has emerged as a promising approach to recover orthologous nuclear genes for large-scale phylogenomic analyses. However, its reliability with low DNA quality and quantity typical of archival specimens, such as herbarium material, remains largely unexplored. We used Rhododendron as a case study to evaluate best practices for DGS in phylogenetic analyses at both deep and shallow scales. We first investigated locus recovery variation with sequencing depth, before evaluating the phylogenetic utility of different sets of loci, including Angiosperms353, target nuclear exons, and extended exon-flanking regions. We found DGS effectively recovered nuclear genes from herbarium specimens, with ∼15× coverage performing similarly to deeper sequencing. The recovery of target exon and flanking regions was improved by using supercontigs as a reference, offering a potential solution to limited sequencing depth. The high-integrity nuclear sequences recovered robust phylogenetic relationships within Rhododendron. Notably, exon-flanking regions showed significant potential for resolving relationships at shallow scales. Genes recovered with taxon-specific references had less missing data than those recovered by Angiosperms353 and generated higher-resolution phylogenetic trees. This study demonstrates the utility of DGS data for obtaining numerous nuclear genes from herbarium specimens for phylogenetic studies, and makes recommendations for best practices regarding sequencing coverage, locus selection, and bioinformatic approaches.

The study of natural hybridization facilitates our understanding of potential adaptive mechanisms in evolution and the process involved in speciation. In this study, we used multiple data types, including morphological traits, ddRAD-seq and ecological niche data, to investigate the differences among Rhododendron × duclouxii hybrid zones and the mechanisms underlying natural hybridization and possible future evolutionary pathways. Our results show that the origins of each hybrid zone are independent, with variations in hybrid formation, structural characteristics, and patterns of genetic components and morphological trait differentiation. There were no significant differences in morphological traits or genetic variation between the F₁ and F₂ generations; however, the range of variation of the F₂ generation was broader than that of the F₁ generation. The distribution and ecological characteristics of R. × duclouxii did not significantly differ from those of the two parental species, indicating weak ecological niche preferences between the hybrid and parental taxa. These results imply that the hybrid zones of R. × duclouxii are characterized by considerable variability, with the magnitude of hybridization in each case likely influenced by unique combinations of biological and ecological factors specific to each hybrid zone. We predict that R. × duclouxii hybrid zones will persist and give rise to complex hybrid swarms, each potentially leading to different evolutionary outcomes.

Mountains serve as exceptional natural laboratories for studying biodiversity due to their heterogeneous landforms and climatic zones. The Himalaya, a global biodiversity hotspot, hosts rich endemic flora, supports vital ecosystem functions, and offers a unique window into multifaceted plant diversity patterns. This review synthesizes research on Himalayan plant diversity, including species, phylogenetic, functional, and genetic dimensions, highlighting knowledge gaps and solutions. Research on Himalayan plant diversity has developed significantly. However, gaps remain, especially in studies on phylogenetic and functional diversity. The region's vegetation ranges from tropical rainforests to alpine ecosystems, with species richness typically following a hump-shaped distribution along elevation gradients. The eastern Himalaya exhibits higher plant diversity than the central and western regions. Low-elevation communities were found to be more functionally diverse, whereas high-elevation communities displayed greater ecological specialization. Communities at mid-elevations tend to show greater phylogenetic diversity than those at higher and lower elevations. The eastern and western flanks of the Himalaya retain high levels of genetic diversity and serve as glacial refugia, whereas the central region acts as a hybrid zone for closely related species. Himalayan plant diversity is shaped by historical, climatic, ecological and anthropogenic factors across space and time. However, this rich biodiversity is increasingly threatened by environmental change and growing anthropogenic pressures. Unfortunately, research efforts are constrained by spatial biases and the lack of transnational initiatives and collaborative studies, which could significantly benefit from interdisciplinary approaches, and other coordinated actions. These efforts are vital to safeguarding the Himalayan natural heritage.

Intraspecific genetic variance and gene flow can support the adaptive evolution of species challenged by climate shifts or novel environmental conditions. Less well understood is how genome organization and gene flow interact in closely related species during evolutionary divergence and differentiation. Here we conducted genomic footprint analyses to determine how three species of Pterocarya (P . stenoptera, P. hupehensis, and P. macroptera), which are sympatric but occupy different elevational niches, adapted to the heterogeneous environment of the Qinling-Daba Mountains, China. We identified candidate genes for environmental adaptation (i.e., PIEZO1, WRKY39, VDAC3, CBL1, and RAF), and also identified regions of gene introgression between P. hupehensis and P. macroptera that show lower genetic load and higher genetic diversity than the rest of their genomes. The same introgressed regions are notably situated in areas of minimal genetic divergence yet they are characterized by elevated recombination rates. We also identified candidate genes within these introgressed regions related to environmental adaptation (TPLC2, CYCH;1, LUH, bHLH112, GLX1, TLP-3, and ABC1). Our findings have thus clarified the important role of gene flow in ecological adaptation and revealed genomic signatures of past introgression. Together, these findings provide a stronger theoretical basis for understanding the ecological adaptation and conservation of Quaternary relict woody plants in East Asia.