小檗科鬼臼亚科多样性格局的演化历史和成因

探究生物多样性在类群和空间不均一性的形成机制对于认识多样性的形成和演化规律具有重要意义,也是生物学研究的热点之一。鬼臼亚科属于小檗科,包含10属约89种,属间物种数量差异巨大。本研究利用比较系统发育学的研究方法,重建了鬼臼亚科的系统发育关系、分化时间和多样化历史,并探讨了生物和非生物因素对净多样化速率的影响。研究结果表明鬼臼亚科起源于92.75Myr,净多样化速率在约23Myr开始明显提升,最显著的净多样化速率转变发生在21Myr附近的淫羊藿属(Epimedium)分支上。基于性状的演化速率分析显示,具有蜜距和分布在东亚亚热带的类群具有较高的净多样化速率,但淫羊藿属特定的距长对其物种的净多样化速率没有影响;果实类型、假种皮和气生茎的有无对类群间净多样化速率无影响。本研究表明功能性状的演化和中新世以来东亚地区季风气候的加强导致了鬼臼亚科内部多样性的分布不均。     

染色体数据的挖掘及其在植物多样性进化研究中的利用

多倍化（或全基因组加倍）是植物物种形成的重要途径,现存的被子植物可能都发生过一次甚至多次多倍化事件。多倍化传统的定义是染色体数目相对于祖先类群呈整倍性增加。其中最常用的研究方法是核型分析,核型能够提供物种的基本细胞学参数,包括染色体数目、倍性水平、核型不对称性、核型变异系数等。目前核型研究的趋势表现出从物种基本核型参数分析逐渐演化到多类群、多学科交叉融合的特点：一方面植物核型分析从种群、物种、科属的类群到生命之树,探讨染色体核型在各支系的进化特征、趋势以及驱动植物系统进化的细胞学机制;另一方面探讨和分析区域或生态系统植物区系的染色体谱或倍性等细胞学特征,可以探究区域地质环境变化或生态环境对染色体倍性等的影响,或通过区域染色体谱的构建,分析区域植物区系的形成和进化历史。因而,植物核型研究为系统发育、分子系统进化、生命之树以及植物区系地理的起源和演化研究提供了新思路。越来越多的新方法、新手段在植物核型分析与多倍化研究中得到运用,从而揭示了植物类群或植物区系的染色体进化以及细胞地理特征。今后植物细胞学研究趋势会向多学科交叉融合,整合各研究领域证据,从不同水平角度综合分析植物核型多样性形成的原因及意义,从而更加全面地认识和理解植物物种多样化与物种形成原因。     

染色体数据的挖掘及其在植物多样性进化研究中的利用

多倍化(或全基因组加倍)是植物物种形成的重要途径,现存的被子植物可能都发生过一次甚至多次多倍化事件。多倍化传统的定义是染色体数目相对于祖先类群呈整倍性增加。其中最常用的研究方法是核型分析,核型能够提供物种的基本细胞学参数,包括染色体数目、倍性水平、核型不对称性、核型变异系数等。目前核型研究的趋势表现出从物种基本核型参数分析逐渐演化到多类群、多学科交叉融合的特点:一方面植物核型分析从种群、物种、科属的类群到生命之树,探讨染色体核型在各支系的进化特征、趋势以及驱动植物系统进化的细胞学机制;另一方面探讨和分析区域或生态系统植物区系的染色体谱或倍性等细胞学特征,可以探究区域地质环境变化或生态环境对染色体倍性等的影响,或通过区域染色体谱的构建,分析区域植物区系的形成和进化历史。因而,植物核型研究为系统发育、分子系统进化、生命之树以及植物区系地理的起源和演化研究提供了新思路。越来越多的新方法、新手段在植物核型分析与多倍化研究中得到运用,从而揭示了植物类群或植物区系的染色体进化以及细胞地理特征。今后植物细胞学研究趋势会向多学科交叉融合,整合各研究领域证据,从不同水平角度综合分析植物核型多样性形成的原因及意义,从而更加全面地认识和理解植物物种多样化与物种形成原因。     

气候生态位进化与物种多样化的关系——以泛热带植物番荔枝科为例

热带地区较高的物种多样性与其气候条件有关,但气候如何影响热带地区物种的多样化却未有定论。为了解气候对热带植物多样性的影响,本研究以泛热带植物番荔枝科为研究对象,利用系统发育比较分析方法,计算了该科植物气候生态位的进化速率,并与该科的净多样化速率进行了相关性分析。结果显示:(1)番荔枝科气候生态位的进化速率较低,但新近分化类群的进化速率相对较高;(2)气候生态位下界(低温与低降水)的进化速率较上界(高温与高降水)快;(3)净多样化速率与气候生态位的进化速率,尤其是温度生态位的进化速率紧密相关。本研究揭示了番荔枝科植物气候生态位的进化对其物种多样性形成的重要作用,对该科在当前气候变化下的保护具有参考意义。     

北京昌平区景观复杂度和局地管理对苹果园传粉蜂多样性的影响

传粉蜂为作物生产和粮食安全提供重要的生态系统服务。随着农业经济的不断发展,土地利用强度加剧,大量自然或半自然生境已经转变为农业用地。景观均质化和集约化管理导致野生蜂多样性下降,从而威胁到农业可持续生产。本研究以北京市昌平区苹果园为对象,探究景观复杂度(半自然生境比例)、局地管理强度(地表开花植物多样性和土壤全氮)及其交互作用对传粉蜂多样性的影响。结果表明: 共捕获传粉蜂8642头,其中人工蜂5125头,野生蜂分属5科14属49种3517头。传粉蜂多样性对景观复杂度和局地管理强度响应的最优尺度在500 m。样点半径500 m范围内,总传粉蜂和野生蜂多度随周围半自然生境增加均呈显著上升趋势。景观复杂度与开花植物多样性的交互作用对总传粉蜂和野生蜂物种丰富度有显著影响。当景观复杂度较低时(≤29.9%),总传粉蜂和野生蜂物种丰富度与开花植物多样性呈显著正相关;而当景观复杂度较高时(>29.9%),总传粉蜂和野生蜂物种丰富度与开花植物多样性呈显著负相关。此外,人工蜂多度随果园内局地开花植物多样性和土壤全氮增加呈显著升高趋势。土壤全氮与开花植物多样性的交互作用对人工蜂多度有显著影响。当土壤全氮含量较低时(≤1.9 g·kg^-1),人工蜂多度与开花植物多样性呈显著正相关;而当土壤全氮含量较高时(>1.9 g·kg^-1),人工蜂多度与开花植物多样性呈显著负相关。农业景观中半自然生境比例的增加有利于提高野生蜂多度,而地表开花植物多样性可以促进传粉蜂多样性,但是受到景观尺度(半自然生境比例)和局地尺度(氮肥施用)的影响。因此,农业景观中野生蜂多样性的维持需要综合考虑多尺度因素来制定保护策略。尽可能保留更高比例的耕地仍然是生产的长期需求,而保持中等景观复杂度,增加地表开花植物多样性,减少氮肥施用量将是促进苹果园传粉蜂多样性的有效方式。     

净多样化速率和进化时间对虎耳草目科间物种多样性差异的影响

不同生物类群包含的物种数目常存在巨大差异,这是生态学和生物学研究中普遍观察到的现象。然而,这一现象产生的原因仍然是未解之谜。从宏观进化的角度,进化时间假说和多样化速率假说是两个比较流行的假说。进化时间假说认为类群的演化时间越长,积累的物种丰富度越高;而多样化速率假说认为类群的净多样化速率越快,则其物种丰富度越高。为验证这两个假说,该文以一棵包含1 539个物种化石定年的虎耳草目系统发育树为基础,通过宏观进化分析获取了虎耳草目内15个科的物种形成和灭绝速率,并计算了每个科的平均多样化速率。结果表明：(1)虎耳草目的物种多样化速率有着增加的趋势,并且多样化速率的增加主要出现在温带和高山类群,如茶藨子科、景天科和芍药科等。(2)采用系统发育广义最小二乘模型(PGLS)和线性回归模型(LM)结果表明,虎耳草目15个科的物种丰富度与科的分化时间和科内物种的最近共同祖先年龄都没有显著相关关系,而与净多样化速率显著正相关(R² =0.380,P<0.05)。该研究支持了多样化速率假说,认为不同科的净多样化速率的差异是导致虎耳草目科间物种数目差异的主要原因之一。全球气候变冷...     

植物功能性状与湿地生态系统土壤碳汇功能

湿地生态系统碳平衡对气候变化极为敏感,是陆地生态系统碳循环响应全球变化的重要环节。然而,湿地生态系统碳汇调节机制仍不十分清楚,并且对影响因子的研究多集中在非生物因子上。综述了植物功能性状和功能性状多样性对湿地生态系统土壤碳汇功能的影响,阐明了生物因子对生态系统碳循环响应全球变化的重要性,介绍了植物功能性状对生态系统碳输入和输出过程的影响,简述了植物功能性状多样性的研究现状及其在指示生态系统碳汇功能现状和预测未来趋势等方面的应用。从优势植物、植物种间关系和植物-微生物种间关系3方面总结了植物功能性状多样性直接和间接影响生态系统碳循环的途径。展望了植物功能性状和功能性状多样性与湿地生态系统土壤碳汇功能的研究前景。     

基于标本和分布信息评估中国虾脊兰属 植物的濒危状况

兰科植物是生物多样性保护的旗舰类群之一, 但如何客观准确地评估兰科植物的濒危状况, 一直是生物多样性保护中急需解决的问题。本文以中国虾脊兰属(Calanthe)植物为例, 探讨了基于馆藏标本和野外分布信息进行兰科植物红色名录濒危等级评估的利弊。我们的研究表明, 馆藏标本能够比较客观地反映物种地理分布信息和相应的野外居群状况, 但对于物种分布的历史变化和受威胁因素反映不足; 而野外工作对于物种的实际分布状况和受威胁因素等的反映比较客观, 但能发现的物种和居群数量有限, 部分极小种群物种在短时间野外工作中很难发现。我们的研究认为, 有2种虾脊兰属植物应被评估为野外灭绝(EW), 16种应被评估为极度濒危(CR)。可见, 中国虾脊兰属植物濒危的状况远比前人的评估结果要严重得多。     

野花带对京郊农田地表蜘蛛多样性的影响

蜘蛛作为农田生态系统中重要的天敌类群,其分布易受田块尺度因素的影响。在农田边种植野花带可以增加景观美感,而对于蜘蛛多样性的影响在国内研究不足。在北京市选取8对农业管理和周边景观组成相似的农田,每对中一块田地毗邻野花带,另一块周围无开花植物生境。通过对农田中的蜘蛛进行监测,探讨野花带对蜘蛛多样性的影响。结果表明:毗邻野花带的农田中蜘蛛多样性高于无野花带的农田,且这种差异在农田内部更为明显;蜘蛛优势种群落分布与野花带性状无统计学显著性相关关系,却与野花带物种多样性和野花带宽度呈一定的正相关。研究表明,构建农田边界野花带有助于增加蜘蛛多样性,进而有助于虫害的生物控制。     

浙江古田山亚热带常绿阔叶林开花物候:气候因素、系统发育关系和功能性状的影响

植物的开花物候受气候因素、植物系统发育关系和功能性状的影响。然而当前植物开花物候研究中未见同时考虑这3个因素的报道。为了解它们相互之间的影响, 本研究利用中国东部地区浙江省古田山国家级自然保护区亚热带常绿阔叶林24 ha大样地(GTS; 118°03′50′′-118°11′12.2′′ E, 29°10′19′′-29°17′41′′ N)设置的130个种子雨收集器5年的开花数据检验这3个因素对开花的影响。结果表明, 古田山植物的开花高峰期集中在5月, 群落开花格局明显受温度和降雨的影响。利用植物DNA条形码数据研究发现, 植物间系统发育关系对古田山植物开花时间有显著影响, 亲缘关系近的物种开花时间更相近。植物的平均开花时间受最大树高的影响, 但不受传粉方式、花色、种子质量和扩散方式的影响。该研究结果说明气候因素、植物系统发育关系和功能性状都可能影响植物开花物候格局, 同时考虑这3个因素能够帮助我们更好地理解开花物候格局。     

Plant polyploidy and non-uniform effects on insect herbivores

Genomic duplication through polyploidy has played a central role in generating the biodiversity of flowering plants. Nonetheless, how polyploidy shapes species interactions or the ecological dynamics of communities remains largely unknown. Here we provide evidence from a 4 year study demonstrating that the evolution of polyploidy has reshaped the interactions between a widespread plant and three species of phytophagous moths. Our results show that polyploidy has produced non-uniform effects, with polyploids less attacked by one insect species, but significantly more attacked by two other species. These results suggest that the evolution of plant polyploidy may not generally confer uniform resistance to multiple species of insect herbivores. In the absence of such a uniform release, the extreme evolutionary success of polyploid plants is probably due to factors other than escape from herbivory. Together, these results suggest that a primary consequence of plant polyploidy may be to shape the ecological structure of plant-insect interactions, thereby providing opportunities for diversification in both plant and insect taxa.     

Environmental causes for plant biodiversity gradients

One of the most pervasive patterns observed in biodiversity studies is the tendency for species richness to decline towards the poles. One possible explanation is that high levels of environmental energy promote higher species richness nearer the equator. Energy input may set a limit to the number of species that can coexist in an area or alternatively may influence evolutionary rates. Within flowering plants (angiosperms), families exposed to a high energy load tend to be both more species rich and possess faster evolutionary rates, although there is no evidence that one drives the other. Specific environmental effects are likely to vary among lineages, reflecting the interaction between biological traits and environmental conditions in which they are found. One example of this is demonstrated by the high species richness of the iris family (Iridaceae) in the Cape of South Africa, a likely product of biological traits associated with reproductive isolation and the steep ecological and climatic gradients of the region. Within any set of conditions some lineages will tend to be favoured over others; however, the identity of these lineages will fluctuate with a changing environment, explaining the highly labile nature of diversification rates observed among major lineages of flowering plants.     

Selection for phenotypic divergence between diploid and autotetraploid Heuchera grossulariifolia

Much of the diversity of flowering plants is associated with genomic duplication through polyploidy. Little is known, however, about the evolutionary mechanisms responsible for the diversification of novel polyploid lineages. We evaluated the possibility that divergence is driven by natural selection by estimating the strength of phenotypic selection acting on three floral traits in sympatric populations of diploid and autotetraploid Heuchera grossulariifolia over three years. Our results demonstrate consistent directional selection for increasing scape length and floral display in both diploid and tetraploid populations. In contrast, selection acting on flowering phenology varied across year and ploidy. Specifically, selection was found to favor late-flowering diploids in 2001 and 2002 but early-flowering tetraploids in 2003. We investigated the mechanistic basis of divergent selection for flowering phenology in 2003 by estimating the relationship between plant flowering phenology and the probability of intercytotype pollinator movement. The results demonstrated that less divergent tetraploids were significantly more likely to experience intercytotype flights than were more divergent tetraploids. This result is consistent with the pattern of phenotypic selection observed. Taken together, our results suggest that divergence of polyploids and their diploid progenitors may be driven by a process analogous to reinforcement whereby selection favors phenotypes that reduce the probability of intercytotype matings with reduced fertility.     

PLANT POLYPLOIDY AND POLLINATION: FLORAL TRAITS AND INSECT VISITS TO DIPLOID AND TETRAPLOID HEUCHERA GROSSULARIIFOLIA

In many polyploid species, polyploids often have different suites of floral traits and different flowering times than their diploid progenitor species. We hypothesized that such differences in floral traits in polyploids may subsequently affect their interactions with pollinating and other insect visitors. We measured floral morphology and flowering phenology in 14 populations of diploid and autotetraploid Heuchera grossulariifolia Rydb. (Saxifragaceae), determined if repeated evolution of independent polyploid lineages resulted in differentiation in floral morphology among those lineages, and ascertained if there was a consistent pattern of differentiation among genetically similar diploid and autotetraploid populations. In addition, we evaluated the differences in suites of floral visitors within a natural community where diploids and autotetraploids occur sympatrically. Overall, flowers of autotetraploid plants were larger and shaped differently than those of diploids, had a different flowering phenology than that of diploids, and attracted different suites of floral visitors. In comparison with flowers of diploids, tetraploid floral morphology varied widely from pronounced differences between cytotypes in some populations to similar flower shapes and sizes between ploidal levels in other populations. Observations of floral visitors to diploids and autotetraploids in a natural sympatric population demonstrated that the cytotypes had different suites of floral visitors and six of the 15 common visitors preferentially visited one ploidy more frequently. Moreover, we also found that floral morphology differed among independent autotetraploid origins, but there was no consistent pattern of differentiation between genetically similar diploid and autotetraploid populations. Hence, the results suggest that the process of polyploidization creates the potential for attraction of different suites of floral visitors. Multiple origins of polyploidy also presents the opportunity for new or different plant-insect interactions among independent polyploid lineages. These differences in turn may affect patterns of gene flow between diploids and polyploids and also among plants of independent polyploid origin. Polyploidy, therefore, may result in a geographic mosaic of interspecific interactions across a species' range, contributing to diversification in both plant and insect groups.     

Polyploidy-associated genome modifications during land plant evolution

The occurrence of polyploidy in land plant evolution has led to an acceleration of genome modifications relative to other crown eukaryotes and is correlated with key innovations in plant evolution. Extensive genome resources provide for relating genomic changes to the origins of novel morphological and physiological features of plants. Ancestral gene contents for key nodes of the plant family tree are inferred. Pervasive polyploidy in angiosperms appears likely to be the major factor generating novel angiosperm genes and expanding some gene families. However, most gene families lose most duplicated copies in a quasi-neutral process, and a few families are actively selected for single-copy status. One of the great challenges of evolutionary genomics is to link genome modifications to speciation, diversification and the morphological and/or physiological innovations that collectively compose biodiversity. Rapid accumulation of genomic data and its ongoing investigation may greatly improve the resolution at which evolutionary approaches can contribute to the identification of specific genes responsible for particular innovations. The resulting, more ‘particulate’ understanding of plant evolution, may elevate to a new level fundamental knowledge of botanical diversity, including economically important traits in the crop plants that sustain humanity.     

中国植物系统和进化生物学研究进展

植物系统和进化生物学旨在探讨植物物种多样性的起源、多样化及其进化的机制, 是综合性越来越强的研究领域。2017年在深圳召开的第19届国际植物学大会(IBC 2017)为中国学者提供了一次难得的展示自身实力的机会和舞台, 同时也极大地推动了中国植物系统与进化生物学领域的研究。值此大会召开5周年之际, 本文拟就中国系统和进化生物学领域近年来取得的主要进展和突破做一简要回顾, 以帮助读者了解中国植物系统和进化研究的发展态势, 并在此基础上展望未来该领域的发展趋势以及面临的机遇和挑战。在过去5年中, 中国学者在植物系统与进化生物学领域的各个方面均取得了令人鼓舞的成绩和突破, 涉及植物起源和物种多样性格局的演变、植物分类和系统发生重建、物种形成和适应性进化、种间互作和协同进化、新性状的起源及其进化发育机制、植物多倍化的机制和多倍体进化、物种濒危机制和物种保护以及栽培植物的起源和驯化等等。这些研究成果不仅在数量上而且在质量上有显著提升, 受到国际学界的广泛关注, 意味着中国学者已经成为国际该领域研究的重要力量, 并将在国际植物系统和进化研究领域发挥更大的作用。     

Polyploidy and self-fertilization in flowering plants

Mating systems directly control the transmission of genes across generations, and understanding the diversity and distribution of mating systems is central to understanding the evolution of any group of organisms. This basic idea has been the motivation for many studies that have explored the relationships between plant mating systems and other biological and/or ecological phenomena, including a variety of floral and environmental characteristics, conspecific and pollinator densities, growth form, parity, and genetic architecture. In addition to these examples, a potentially important but poorly understood association is the relationship between plant mating systems and genome duplication, i.e., polyploidy. It is widely held that polyploid plants self-fertilize more than their diploid relatives, yet a formal analysis of this pattern does not exist. Data from 235 species of flowering plants were used to analyze the association between self-fertilization and ploidy. Phylogenetically independent contrasts and cross-species analyses both lend support to the hypothesis that polyploids self-fertilize more than diploids. Because polyploidy and self-fertilization are so common among angiosperms, these results contribute not only to our understanding of the relationship between mating systems and polyploidy in particular, but more generally, to our understanding of the evolution of flowering plants.     

Using taxonomic and phylogenetic evenness to compare diversification in two Island Floras

This study compares the phylogenetic structure in the Canary Islands and Hawaii by means of the distributions of the species number for plant families (Taxonomic evenness) and lineages (Phylogenetic evenness) across archipelagos and across habitats in both archipelagos using the Gini coefficient. We then investigate phylogenies to identify particular habitats contributing to such differences using Taxonomic distinctness (AvTD) and its variation (VarTD).Our results show that the distribution of species number among Hawaiian lineages is much more uneven than the Canary Islands. In contrast, Hawaii produces a more even distribution of species number by family than the Canary Islands. This may be due to the Hawaiian Flora being derived from considerably fewer colonists than the Canarian Flora as a result of its much greater degree of isolation. At the same time, Hawaii is represented by the same number of families as the Canary Islands. This may stem from Hawaii's flora being derived from a greater range of source areas despite its isolation. Finally, there is much more diversification spread across a larger number of lineages in Hawaii. The higher degree of Hawaiian diversification may be due to a greater range of habitats, more diverse and phylogenetically distinct floristic sources, and low initial species diversity resulting from extreme isolation.Two Canarian habitats (Rock communities and Thermophilous habitats) and one Hawaiian habitat (Wet communities) contribute to the differences in phylogenetic structure between the two archipelagos. These habitats exhibit disproportionate levels of unevenness and may represent centres of diversification. We propose a combination of two habitat properties, high receptivity and low stability, to explain these results.     

Glacial History Affected Phenotypic Differentiation in the Alpine Plant,Campanula thyrsoides

Numerous widespread Alpine plant species show molecular differentiation among populations from distinct regions. This has been explained as the result of genetic drift during glacial survival in isolated refugia along the border of the European Alps. Since genetic drift may affect molecular markers and phenotypic traits alike, we asked whether phenotypic differentiation mirrors molecular patterns among Alpine plant populations from different regions. Phenotypic traits can be under selection, so we additionally investigated whether part of the phenotypic differentiation can be explained by past selection and/or current adaptation. Using the monocarpic Campanula thyrsoides as our study species, a common garden experiment with plants from 21 populations from four phylogeographic groups located in regions across the Alps and the Jura Mountains was performed to test for differentiation in morphological and phenological traits. Past selection was investigated by comparing phenotypic differentiation among and within regions with molecular differentiation among and within regions. The common garden results indicated regional differentiation among populations for all investigated phenotypic traits, particularly in phenology. Delayed flowering in plants from the South-eastern Alps suggested adaptation to long sub-mediterranean summers and contrasted with earlier flowering of plants experiencing shorter growing seasons in regions with higher elevation to the West. Comparisons between molecular and phenotypic differentiation revealed diversifying selection among regions in height and biomass, which is consistent with adaptation to environmental conditions in glacial refugia. Within regions, past selection acted against strong diversification for most phenotypic traits, causing restricted postglacial adaptation. Evidence consistent with post-glacial adaptation was also given by negative correlation coefficients between several phenotypic traits and elevation of the population''s origin. In conclusion, our study suggests that, irrespective of adaptation of plants to their current environment, glacial history can have a strong and long-lasting influence on the phenotypic evolution of Alpine plants.