Aims: It has been assumed that montane species will undergo upslope shifts in response to climate warming and their range sizes are therefore predicted to decrease. However, this view has been ...challenged because a recent study (Elsen & Tingley, 2015) indicated that land surface area increases with increasing altitude in some mountains. To test this prediction, we used one of the world's biodiversity hotspots as a study system to examine overall patterns of plant distribution shift in response to climate warming. Location: The Hengduan Mountains and adjacent regions. Methods: Based on distribution data for 151 species at a resolution of 2.5 arc minutes, we employed ecological niche modelling to model their distributions under the climatic conditions of the Last Glacial Maximum, Current (2017), and 2050 separately. We examined the distributional shifts of these species, especially with respect to altitude and range size, in response to two periods of stepwise climate warming. Results: All the montane plants sampled shifted upward during the two warming stages, but not only northward, some shifted westward or in other directions. In contrast with the expected consistent loss of range when shifting upward, 63.6% of the plants expanded their range size continuously since the LGM. Only 11.9% of the plants contracted their range size continuously from the LGM to 2050. Estimates of species richness in the regions studied changed greatly, but in an unbalanced manner, from the LGM to the Current and from the Current to 2050. Main conclusions: Numerous montane plants in the Hengduan Mountains are predicted to expand their range sizes as they shift upslope in response to climate warming. Our results highlight the possibility that more available land surface area due to the heterogeneous topography along altitudinal gradients and the adjacent large Qinghai-Tibet Plateau sensu stricto can mediate the range loss of the montane plants under climate warming. These findings are crucial for estimating the future range sizes of plants and planning biodiversity protection for mountain ecosystems under the anticipated warming of the world's climate.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Trees are vital to the survival of numerous species and to forest ecosystem functioning. However, the current distribution, vulnerability to extinction, and conservation priorities of globally ...endangered trees are not well known. We mapped the global distribution of 1686 tree species listed as endangered on the International Union for the Conservation of Nature Red List and identified conservation priority for them based on species richness, life‐history traits, evolutionary distinctiveness, future climate change, and intensity of human activities. We also evaluated the impacts of various threats to these endangered tree species and evaluated the effectiveness of their protection based on the percentage of the species' range inside protected areas. The worldwide distribution of endangered trees, from the tropics through temperate zones, was uneven. Most endangered tree species were not protected in their native ranges, and only 153 species were fully protected. Hotspots of tree diversity occurred primarily in the tropics, and 79.06% of these were highly vulnerable to threats. We identified 253 areas of high priority for the conservation of endangered trees that are highly threatened and insufficiently protected. In particular, 43.42% of unprotected tree species in priority areas lacked recommended conservation measures or had no associated conservation plan. The priority conservation areas and unprotected trees we identified serve as a guideline for future management underpinning the post‐2020 global biodiversity framework.
Prioridades de conservación para los árboles amenazados que enfrentan múltiples amenazas en todo el mundo
Resumen
Los árboles son vitales para la supervivencia de numerosas especies y para el funcionamiento de los ecosistemas forestales. Sin embargo, no se conoce muy bien la distribución actual, vulnerabilidad a la extinción y prioridades de conservación de los árboles amenazados a nivel mundial. Mapeamos la distribución global de 1686 especies de árboles catalogadas como en peligro por la Lista Roja de la Unión Internacional para la Conservación de la Naturaleza e identificamos su prioridad de conservación con base en la riqueza de especies, características de historia de vida, singularidad evolutiva, cambio climático futuro e intensidad de las actividades humanas. También evaluamos el impacto de varias amenazas sobre estas especies y analizamos la efectividad de su protección con base en el porcentaje de la distribución de la especie ubicado dentro de un área protegida. La distribución mundial de árboles en peligro, desde los trópicos y hasta las zonas templadas, fue desigual. La mayoría de las especies no estaban protegidas dentro de su distribución nativa y sólo 153 especies contaban con protección completa. Los puntos calientes de diversidad de árboles se ubicaron principalmente en los trópicos, y el 79.06% de estos tenían una vulnerabilidad alta ante las amenazas. Identificamos 253 áreas de gran prioridad para la conservación de los árboles en peligro que están amenazados y con poca protección. En particular, el 43.42% de las áreas sin protección dentro de las áreas prioritarias no contaban con las medidas recomendadas de conservación o no tenían asociado un plan de conservación. Las áreas prioritarias de conservación y los árboles sin protección que identificamos son una pauta para futuros manejos que apuntalan el marco de trabajo post‐2020 para la biodiversidad.
【摘要】
树木对众多物种的生存和森林生态系统功能的维持至关重要。然而, 全球濒危树木的现有分布、灭绝脆弱性和保护优先性尚不清楚。我们绘制了 1686 种世界自然保护联盟濒危树木的全球分布格局, 并基于物种丰富度、生活史特征、进化特异性、未来气候变化和人类活动强度对其优先保护区进行识别。我们评估了多种威胁对濒危树木的影响, 并根据保护区覆盖物种分布范围的百分比来评估现有保护区的保护效力。从热带到温带, 濒危树木在世界范围内呈现非均匀分布。大多数濒危树木在其原生分布范围内缺乏保护, 只有 153 种树木得到充分保护。树木多样性热点主要集中在热带区域, 其中 79.06% 热点区域的物种面临高度威胁。我们识别了 253 个亟待优先保护濒危树木的区域, 这些濒危树木面临严重威胁且现有保护不足。其中, 43.42% 的未受保护树木缺少有效的保护措施或没有相关的保护计划。在 2020 年后全球生物多样性框架下, 识别的优先保护区和未受保护树木可作为未来濒危树木管理的指导方针。
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Camptothecin and its derivatives are widely used for treating malignant tumors. Previous studies revealed only a limited number of candidate genes for camptothecin biosynthesis in Camptotheca ...acuminata, and it is still poorly understood how its biosynthesis of camptothecin has evolved. Here, we report a high-quality, chromosome-level C. acuminata genome assembly. We find that C. acuminata experiences an independent whole-genome duplication and numerous genes derive from it are related to camptothecin biosynthesis. Comparing with Catharanthus roseus, the loganic acid O-methyltransferase (LAMT) in C. acuminata fails to convert loganic acid into loganin. Instead, two secologanic acid synthases (SLASs) convert loganic acid to secologanic acid. The functional divergence of the LAMT gene and positive evolution of two SLAS genes, therefore, both contribute greatly to the camptothecin biosynthesis in C. acuminata. Our results emphasize the importance of high-quality genome assembly in identifying genetic changes in the evolutionary origin of a secondary metabolite.
Sichuan pepper is a commonly used spice in Asian cuisine. Sanshools and wgx‐50/gx‐50 isolated from it have been shown to possess a wide spectrum of medicinal properties. Here we generated a ...chromosome‐level genome assembly of one Sichuan pepper species Zanthoxylum armatum characterized by drought tolerance and apomixis. Analyses of functionally related genes suggested that increased gene copy number and expression level of drought‐tolerant genes might play an important role in improving drought tolerance of Z. armatum. Moreover, a gene encoding an RWP‐RK domain‐containing protein was shown to contribute to apomixis in Z. armatum, which was further characterized by overexpression in Arabidopsis thaliana. Furthermore, based on gene homology searching and co‐expression patterns of metabolite concentration and gene expressions, we identified a number of candidate genes involved in the biosynthesis of sanshools and wgx‐50/gx‐50. Taken together, our results yield valuable insights for understanding the evolution of apomixis, drought tolerance, and alkaloid biosynthesis in Z. armatum.
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The molecular era has fundamentally reshaped our knowledge of the evolution and diversification of angiosperms. One outstanding question is the phylogenetic placement of Amborella trichopoda Baill., ...commonly thought represent the first lineage of extant angiosperms. Here, we leverage publicly available data and provide a broad coalescentbased species tree estimation of 45 seed plants. By incorporating 310 nuclear genes, our coalescent analyses strongly support a clade containing Amborella plus water lilies (i.e., Nymphaeales) that is sister to all other angiosperms across different nucleotide rate partitions. Our results also show that commonly applied concatenation methods produce strongly supported, but incongruent placements of Amborella: slow-evolving nucleotide sites corroborate results from coalescent analyses, whereas fast-evolving sites place Amborella alone as the first lineage of extant angiosperms. We further explored the performance of coalescent versus concatenation methods using nucleotide sequences simulated on (i) the two alternate placements of Amborella with branch lengths and substitution model parameters estimated from each of the 310 nuclear genes and (ii) three hypothetical species trees that are topologically identical except with respect to the degree of deep coalescence and branch lengths. Our results collectively suggest that the Amborella alone placement inferred using concatenation methods is likely misled by fast-evolving sites. This appears to be exacerbated by the combination of long branches in stem group angiosperms, Amborella, and Nymphaeales with the short internal branch separating Amborella and Nymphaeales. In contrast, coalescent methods appear to be more robust to elevated substitution rates.
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BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Under global warming, advances in spring phenology due to rising temperatures have been widely reported. However, the physiological mechanisms underlying the advancement in spring phenology ...still remain poorly understood. Here, we investigated the effect of temperature during the previous growing season on spring phenology of current year based on the start of season extracted from multiple long-term and large-scale phenological datasets between 1951 and 2018. Our findings indicate that warmer temperatures during previous growing season are linked to earlier spring phenology of current year in temperate and boreal forests. Correspondingly, we observed an earlier spring phenology with the increase in photosynthesis of the previous growing season. These findings suggest that the observed warming-induced earlier spring phenology is driven by increased photosynthetic carbon assimilation in the previous growing season. Therefore, the vital role of warming-induced changes in carbon assimilation should be considered to accurately project spring phenology and carbon cycling in forest ecosystems under future climate warming.
Ecologists are increasingly making use of molecular phylogenies, especially in the fields of community ecology and conservation. However, these phylogenies are often used without full appreciation of ...their underlying assumptions and uncertainties. A frequent practice in ecological studies is inferring a phylogeny with molecular data from taxa only within the community of interest. These “inferred community phylogenies” are inherently biased in their taxon sampling. Despite the importance of comprehensive sampling in constructing phylogenies, the implications of using inferred community phylogenies in ecological studies have not been examined. Here, we evaluate how taxon sampling affects the quantification and comparison of community phylogenetic diversity using both simulated and empirical data sets. We demonstrate that inferred community trees greatly underestimate phylogenetic diversity and that the probability of incorrectly ranking community diversity can reach up to 25%, depending on the dating methods employed. We argue that to reach reliable conclusions, ecological studies must improve their taxon sampling and generate the best phylogeny possible.
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Earlier spring phenological events have been widely reported in plants under global warming. Recent studies reported a slowdown in the warming‐induced advanced spring phenology in temperate regions. ...However, previous research mainly focused on daily mean temperature, thus neglecting the asymmetric phenological responses to daytime and nighttime temperature. Using long‐term records of leaf unfolding in eight deciduous species at 1300 sites across central Europe, we assessed and compared the effects of daytime temperature, nighttime temperature, and photoperiod on leaf unfolding during 1951–1980 and 1981–2013. Although leaf unfolding was advanced by daytime warming during 1951–2013, the advancing responses of leaf unfolding significantly decreased from 1951–1980 to 1981–2013 due to a lower accumulation of chilling units by daytime warming. Nighttime warming delayed leaf unfolding during 1951–1980 but advanced it during 1981–2013 due to a higher accumulation of chilling units by nighttime warming. In contrast, critical daylength and plasticity of leaf unfolding dates remained unchanged between 1951 and 2013. Our study provided evidence that daytime warming instead of nighttime warming accounts for the slowdown in the advancing spring phenology and implied that nighttime warming‐induced earlier spring phenology may be buffering the slowdown of the advanced spring phenology by daytime warming. The response of spring phenology to nighttime temperature may override that to daytime temperature under the actual trends in global warming.
Advancing responses of leaf unfolding to daytime temperature significantly decreased from the period 1951–1980 to 1981–2013, whereas nighttime warming responses converted from delaying during 1951–1980 to advancing during 1981–2013.
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Although more frequently discussed recently than previously, the role of ecology in homoploid hybrid and allopolyploid speciation has not been subjected to comparative analysis. We examined abiotic ...niche divergence of 22 assumed homoploid hybrid species and 60 allopolyploid species from that of their progenitors. Ecological niche modeling was employed in an analysis of each species’ fundamental niche, and ordination methods were used in an analysis of realized niches. Both analyses utilized 100,000 georeferenced records. From estimates of niche overlap and niche breadth, we identified for both types of hybrid species four niche divergence patterns: niche novelty, niche contraction, niche intermediacy, and niche expansion. Niche shifts involving niche novelty were common and considered likely to play an important role in the establishment of both types of hybrid species, although more so for homoploid hybrid species than for allopolyploid species. Approximately 70% of homoploid hybrid species versus 37% of allopolyploid species showed shifts in the fundamental niche from their parents, and ∼86% versus ∼52%, respectively, exhibited shifts in the realized niche. Climate was shown to contribute more than soil and landform to niche shifts in both types of hybrid species. Overall, our results highlight the significance of abiotic niche divergence for hybrid speciation, especially without genome duplication.
• Phylogenetic analysis is complicated by interspecific gene flow and the presence of shared ancestral polymorphisms, particularly those maintained by balancing selection. In this study, we aimed to ...examine the prevalence of these factors during the diversification of Populus, a model tree genus in the Northern Hemisphere.
• We constructed phylogenetic trees of 29 Populus taxa using 80 individuals based on re-sequenced genomes. Our species tree analyses recovered four main clades in the genus based on consensus nuclear phylogenies, but in conflict with the plastome phylogeny. A few interspecific relationships remained unresolved within the multiple-species clade because of inconsistent gene trees. Our results indicated that gene flow has been widespread within each clade and also occurred among the four clades during their early divergence.
• We identified 45 candidate genes with ancient polymorphisms maintained by balancing selection. These genes were mainly associated with mating compatibility, growth and stress resistance.
• Both gene flow and selection-mediated ancient polymorphisms are prevalent in the genus Populus. These are potentially important contributors to adaptive variation. Our results provide a framework for the diversification of model tree genus that will facilitate future comparative studies.
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