被子植物成花诱导和性别决定机制的研究进展

开花植物具有多样性的生殖系统,其中单性花的形成是促进异交、避免自交衰退、保持遗传多样性的重要途径。单性花物种分布于被子植物不同进化分支上的事实表明,物种的雌雄异花性可能是通过不同的机制进化形成的。本文从花发育、性染色体、植物激素和环境因素四个方面,阐述了被子植物性别分化调控机制的研究进展。     

被子植物性系统及其可塑性

繁殖是生物适合度的最终表现,有性繁殖相关性状的多态性极大地促进了物种分化和生物多样性的维持,并影响着植物对环境变化的响应。在种群水平上,被子植物的花有雌花、雄花和两性花三种性表型,三种性表型在种群中的分布和频率即定义了种群的性系统。被子植物的性系统包含植物影响性分配和交配的相关特性,决定着雌配子、雄配子在种群中的频率、交配机会及交配方式,是有性繁殖的关键性状,在被子植物中表现出丰富的多态性,在种群水平上分为性单态和性多态两大类。性单态为被子植物的古老性状,而性多态在100多个被子植物科中独立进化产生。被子植物性系统多态性及其变化机理一直是进化生物学与生态学的热点问题之一。该文以种群水平的性多态为对象,总结了被子植物性系统的类型、表达的遗传基础、分布频率,以及遗传因子、非生物环境和交配环境对性系统表达和性分配的影响。     

果实起源与多样化的进化发育机制

果实的起源与多样化是植物对陆地生态系统长期适应的结果,与植物的种群繁衍和通过种子传播以适应更广阔的生存空间密切相关.这一进化现象与过程造就了被子植物的起源与极大繁盛.揭示果实的起源与多样化以及其适应性进化机制是进化生物学研究的核心科学问题之一.本文综述了近年来在植物果实形态(大小和形状)、果实附属结构的形态创新、果实类型等进化发育研究方面的主要进展,并对该领域的未来研究方向和重点等进行了展望.     

云南被子植物菊类分支的系统发育多样性及其分布格局

全球气候变化与人为活动等因素导致的生物多样性丧失,引起了全球各界对生物多样性保护的高度关注。传统生物多样性保护主要对物种、特有种、受威胁物种的种类组成及其分布模式开展研究,忽视了进化历史在生物多样性保护中的作用。云南是全球生物多样性热点地区的交汇区,生物多样性的保护历来受到广泛关注,为了更好地探讨云南生物多样性的保护措施,该研究以云南被子植物菊类分支物种为研究对象,基于物种间的演化关系,结合其地理分布,从进化历史的角度探讨物种、特有种、受威胁物种的种类组成及系统发育组成的分布格局,并整合自然保护地的空间分布,识别生物多样性的重点保护区域。结果表明：云南被子植物菊类分支的物种、特有种及受威胁物种的物种密度与系统发育多样性均显著正相关;通过零模型分析发现,由南向北标准化系统发育多样性逐渐降低;云南南部、东南部、西北部是云南被子植物菊类分支的重点保护区域,加强这些区域的保护,将最大化地保护生物多样性的进化历史和进化潜能。由此可见,融合进化历史信息的植物多样性格局分析不仅有助于更加深入地理解植物多样性的形成与演变,也为生物多样性保护策略的制定提供更多的思路。     

MADS-box基因家族基因重复及其功能的多样性

基因的重复(duplication)及其功能的多样性(diversification)为生物体新的形态进化提供了原材料。MADS-box基因在植物(特别是被子植物)的进化过程中发生了大规模的基因重复事件而形成一个多基因家族。MADS-box基因家族的不同成员在植物生长发育过程中起着非常重要的作用,在调控开花时间、决定花分生组织和花器官特征以及调控根、叶、胚珠及果实的发育中起着广泛的作用。探讨MADS-box基因家族的进化历史有助于深入了解基因重复及随后其功能分化的过程和机制。本文综述了MADS-box基因家族基因重复及其功能分化式样的研究进展。     

MADS-box 基因家族基因重复及其功能的多样性

基因的重复(duplication)及其功能的多样性(diversification)为生物体新的形态进化提供了原材料。MADS-box基因在植物(特别是被子植物)的进化过程中发生了大规模的基因重复事件而形成一个多基因家族。MADS-box基因家族的不同成员在植物生长发育过程中起着非常重要的作用, 在调控开花时间、决定花分生组织和花器官特征以及调控根、叶、胚珠及果实的发育中起着广泛的作用。探讨MADS-box基因家族的进化历史有助于深入了解基因重复及随后其功能分化的过程和机制。本文综述了MADS-box基因家族基因重复及其功能分化式样的研究进展。     

果实分类系统的修订和教学——植物学教材质疑(十)

果实是被子植物特有的结构,它通过保护种子、帮助种子传播促进了被子植物的兴旺发达。果实的形态结构具高度多样性,使得构建一个令人满意的果实分类系统成为十分困难的事情。本文重新定义了一些果实类型,并修订了植物学教材采用的果实分类系统:1)将浆果状核果和梨果分别归入核果类和浆果类; 2)将分果与裂果、闭果并列,并提出分果新类型:节荚、节裂角果和分角果; 3)将闭果分为坚果和瘦果。瘦果包括真瘦果、小瘦果、下位瘦果、颖果、胞果和具翅瘦果; 4)长、短角果被归入蒴果,花生的果实归入坚果。关于果实分类教学,建议引导学生探讨果实的民间分类和植物学分类之间的差异,果皮特征与种皮、种子数量的关系以及果实的分类学价值、果实类型的演化。     

被子植物翅果的多样性及演化

翅果能够依靠风力进行传播, 可能是被子植物快速散布和物种分化的一个重要因素。狭义的翅果是指果皮延伸成翅且不开裂的干果; 广义的翅果则包括果皮、花被片或苞片形成果翅的所有果实。根据果翅形态及其生长方式的不同, 广义的翅果可分为单侧翅果、周位翅果(圆翅果与蝶翅果)、棱翅果、披针翅果、翼状萼翅果、叶状苞翅果6种类型, 其空中运动方式有自旋式(单侧翅果、翼状萼翅果)、波浪式(周位翅果、叶状苞翅果)、翻滚自旋式(周位翅果)、直升机式(披针翅果、翼状萼翅果)和滚筒式(棱翅果)。棱翅果与圆翅果在被子植物基部类群樟目就有发生, 并同时出现在单子叶植物和双子叶植物中, 可能是最早出现的翅果类型。翅果的演化过程呈现出果翅数量增加、果翅偏向单侧和果翅负荷(果实质量与果翅面积之比)降低的趋势, 以利于适应较小的风并增加传播距离。果翅除了促进果实与种子的风力传播外, 还具有物理防御、调节种子萌发和促进二次传播等作用。泛热带分布的金虎尾科有着极其丰富的翅果类型, 与其多次跨洋长距离扩散密切相关, 可以作为研究翅果适应与演化的一个模式类群。结合生态和演化-发育生物学方法, 研究不同类型翅果在适应风力传播方面的差异、萼片或苞片发育成翅的分子与遗传机制、翅果不同类型的演化历史及其对被子植物物种多样性的影响等是今后值得探讨的重要问题。     

自花传粉与异花传粉:何者更进化?——植物学教材质疑(二)

传粉生物学的学习对理解被子植物多样性至关重要.中文植物学教材均教导学生,自花传粉是原始的传粉方式,异花传粉更为进化,因为前者会导致近交衰退,而后者具杂交优势.这种说法其实是对进化内涵的误解.被子植物的基部类群以异花传粉为主,而自花传粉少见且是次生的;从异花传粉转变为自花传粉在被子植物中反复、独立地发生.自花传粉之所以被...     

中国裸子植物的物种多样性格局及其影响因子

物种多样性的大尺度空间格局是宏观生态学和生物地理学研究的核心问题之一。本文利用中国裸子植物分布数据, 结合气候、地形等环境信息, 分析了中国裸子植物物种多样性的大尺度格局及其影响因素, 比较了不同类群之间物种多样性格局和主导因子的差异, 并探讨了裸子植物在植物区系中所占比重的地理格局。结果表明, 中国裸子植物的物种多样性总体上呈现南高北低的趋势, 物种多样性在横断山区最高。在裸子植物的三个主要类群中, 松柏亚纲的物种多样性格局与整体相似, 买麻藤亚纲的多样性高值区则出现在中国西北部的干旱地区, 苏铁亚纲的分布区较为狭窄, 主要集中在南方地区。线性回归分析结果表明, 空间异质性和降水因子对中国裸子植物多样性格局的解释率最高, 末次冰期以来的气温变化、海拔高差和能量因子次之。这表明中国裸子植物物种多样性的格局受到了多种因素的影响, 其中空间异质性和降水因子影响最大。进一步分析发现, 物种多样性格局的主导因子在不同类群之间具有显著差异, 这可能反映了这些类群的进化历史以及生理适应的差异。裸子植物与被子植物的比例具有明显的空间格局: 在东部、南部气候环境优越的地区, 裸子植物与被子植物的比例低于0.06; 而在西部、北部等气候环境比较恶劣的地区, 裸子植物的比例则显著上升。回归分析表明, 能量和水分因子显著影响了裸子植物与被子植物的比例。随着能量的降低和降水的减少, 裸子植物与被子植物的比例会显著升高, 这可能是由于被子植物在温暖湿润地区具有较强竞争优势, 但裸子植物对极端环境具有更好的适应。     

How different types of pattern formation mechanisms affect the evolution of form and development

Here we investigate how development and evolution can affect each other by exploring what kind of phenotypic variation is produced by different types of developmental mechanisms. A limited number of developmental mechanisms are capable of pattern formation in development. Two main types have been identified. In morphodynamic mechanisms, induction events and morphogenetic processes, such as simple growth, act at the same time. In morphostatic mechanisms, induction events happen before morphogenetic mechanisms, and thus growth cannot influence the induction of a pattern. We present a study of the variational properties of these developmental mechanisms that can help to understand how and why a developmental mechanism may become involved in the evolution and development of a particular morphological structure. Using existing models of pattern formation in teeth, an extensive simulation analysis of the phenotypic variation produced by different types of developmental mechanisms is performed. The studied properties include the amount and diversity of the phenotypic variation produced, the complexity of the phenotypic variation produced, and the relationship between phenotype and genotype. These variational properties are so different between different types of mechanisms that the relative involvement of these types of mechanisms in evolutionary innovation and in different stages of development can be estimated. In addition, type of mechanism affects the tempo and mode of morphological evolution. These results suggest that the basic principles by which development is organized can influence the likelihood of morphological evolution.     

FRUIT EVOLUTION AND DIVERSIFICATION IN CAMPANULID ANGIOSPERMS

With increases in both the size and scope of phylogenetic trees, we are afforded a renewed opportunity to address long‐standing comparative questions, such as whether particular fruit characters account for much of the variation in diversity among flowering plant clades. Studies to date have reported conflicting results, largely as a consequence of taxonomic scale and a reliance on potentially conservative statistical measures. Here we examine a larger and older angiosperm clade, the Campanulidae, and infer the rates of character transitions among the major fruit types, emphasizing the evolution of the achene fruits that are most frequently observed within the group. Our analyses imply that campanulids likely originated bearing capsules, and that all subsequent fruit diversity was derived from various modifications of this dry fruit type. We also found that the preponderance of lineages bearing achenes is a consequence of not only being a fruit type that is somewhat irreversible once it evolves, but one that also seems to have a positive association with diversification rates. Although these results imply the achene fruit type is a significant correlate of diversity patterns observed across campanulids, we conclude that it remains difficult to confidently and directly view this character state as the actual cause of increased diversification rates.     

4种形态类型诸葛菜的等位酶变异及遗传多样性分析

以采自江苏省南京市4个样点的4种不同形态类型(紫花毛果、紫花光果、白花光果和白花毛果)诸葛菜〔Orychophragmus violaceus(L.)O.E.Schulz〕63个单株为研究对象,采用不连续聚丙烯酰胺凝胶电泳技术(SDS-PAGE)对过氧化物酶同工酶(POD)、乙醇脱氢酶(ADH)、谷氨酸脱氢酶(GDH)、超氧化物歧化酶(SOD)和多酚氧化酶(PPO)酶谱进行了分析,并基于5个等位酶的酶谱分析结果对4种形态类型诸葛菜的遗传多样性进行了研究。结果表明:5个等位酶系统共包含12个位点32个等位基因,其中POD-1、POD-4、POD-5、POD-6、ADH-1、PPO-1、SOD-1和SOD-2为多态性位点;除具有共有谱带外,不同类型诸葛菜还具有各自特有的酶谱特征,其中,GDH-2的b带和c带分别是紫花类型和白花类型的特有谱带。紫花毛果、紫花光果和白花毛果类型的多态位点百分率(PPL)均为58.33%,而白花光果的PPL为66.67%;紫花毛果、紫花光果、白花光果和白花毛果每个位点的平均等位基因数分别为2.42、2.25、2.42和1.83,平均期望杂合度分别为0.35、0.30、0.38和0.29。4种形态类型诸葛菜的总基因多样度平均值为0.61,类型内基因多样度平均值为0.49,明显大于类型间基因多样度平均值(0.12);类型间的基因分化系数平均值为0.195,表明总基因多样性的80.5%来源于类型内。紫花光果和白花毛果类型间的遗传一致度最低(0.724 4)且遗传距离最大(0.322 5),而2个白花类型间的遗传一致度最高(0.954 1)且遗传距离最小(0.047 1)。研究结果显示:诸葛菜的种内变异程度很大、遗传分化程度较高,但在各类型内具有较高的遗传相似性。     

The evolution of cell types in animals: emerging principles from molecular studies

Cell types are fundamental units of multicellular life but their evolution is obscure. How did the first cell types emerge and become distinct in animal evolution? What were the sets of cell types that existed at important evolutionary nodes that represent eumetazoan or bilaterian ancestors? How did these ancient cell types diversify further during the evolution of organ systems in the descending evolutionary lines? The recent advent of cell type molecular fingerprinting has yielded initial insights into the evolutionary interrelationships of cell types between remote animal phyla and has allowed us to define some first principles of cell type diversification in animal evolution.     

Relationships within tribe Lycieae (Solanaceae): paraphyly of Lycium and multiple origins of gender dimorphism

We infer phylogenetic relationships among Lycium, Grabowskia, and the monotypic Phrodus microphyllus, using DNA sequence data from the nuclear granule-bound starch synthase gene (GBSSI, waxy) and the chloroplast region trnT-trnF. This is the first comprehensive molecular phylogenetic study of tribe Lycieae (Solanaceae). In addition to providing an understanding of evolutionary relationships, we use the phylogenetic hypotheses to frame our studies of breeding system transitions, floral and fruit evolution, and biogeographical patterns within Lycieae. Whereas Lycium is distributed worldwide, Phrodus and the majority of Grabowskia species are restricted to South America. Tribe Lycieae is strongly supported as monophyletic, but Lycium likely includes both Grabowskia and Phrodus. Results also suggest a single dispersal event from the Americas to the Old World, and frequent dispersal between North and South America. The diversity of fruit types in Lycieae is discussed in light of dispersal patterns and recent work on fruit evolution across Solanaceae. Dimorphic gender expression has been studied previously within Lycium, and results indicate that transitions in sexual expression are convergent, occurring multiple times in North America (a revised estimate from previous studies) and southern Africa.     

Evolution of fruit types and seed dispersal:A phylogenetic and ecological snapshot

Success of flowering plants is greatly dependent on effective seed dispersal. Specific fruit types aid different mechanisms of seed dispersal. However, little is known about what evolutionary forces have driven the diversification of fruit types and whether there were phylogenetic constraints on fruit evolution among angio-sperm lineages. To address these questions, we first surveyed the orders and families of angiosperms for fruit types and found no clear association between fruit types and major angiosperm lineages, suggesting there was little phylogenetic constraint on fruit evolution at this level. We then surveyed fruit types found in two contrasting habitats: an open habitat including the Indian desert and North American plains and prairies, and a closed forest habitat of Australian tropical forest. The majority of genera in the survey of tropical forests in Australia were fleshy fruit trees, whereas the majority of genera in the survey of prairies and plains in central North America were herbs with capsules and achenes. Both capsules and achenes are frequently dispersed by wind in the open, arid habitat, whereas fleshy fruits are generally dispersed by animals. Since desert and plains tend to provide continuous wind to aid dispersal and there are more abundant mammal and bird dispersers in the closed forest, this survey suggests that fruit evolution was driven at least in part by dispersal agents abundant in particular habitats.     

果实类型和种子传播的进化:系统发育和生态学简论

Success of flowering plants is greatly dependent on effective seed dispersal. Specific fruit types aid different mechanisms of seed dispersal. However, little is known about what evolutionary forces have driven the diversification of fruit types and whether there were phylogenetic constraints on fruit evolution among angiosperm lineages. To address these questions, we first surveyed the orders and families of angiosperms for fruit types and found no clear association between fruit types and major angiosperm lineages, suggesting there was little phylogenetic constraint on fruit evolution at this level. We then surveyed fruit types found in two contrasting habitats an open habitat including the Indian desert and North American plains and prairies, and a closed forest habitat of Australian tropical forest. The majority of genera in the survey of tropical forests in Australia were fleshy fruit trees, whereas the majority of genera in the survey of prairies and plains in central North America were herbs with capsules and achenes. Both capsules and achenes are frequently dispersed by wind in the open, arid habitat, whereas fleshy fruits are generally dispersed by animals. Since desert and plains tend to provide continuous wind to aid dispersal and there are more abundant mammal and bird dispersers in the closed forest, this survey suggests that fruit evolution was driven at least in part by dispersal agents abundant in particular habitats.     

Evolution of Wolbachia cytoplasmic incompatibility types

The success of obligate endosymbiotic Wolbachia infections in insects is due in part to cytoplasmic incompatibility (CI), whereby Wolbachia bacteria manipulate host reproduction to promote their invasion and persistence within insect populations. The observed diversity of CI types raises the question of what the evolutionary pathways are by which a new CI type can evolve from an ancestral type. Prior evolutionary models assume that Wolbachia exists within a host individual as a clonal infection. While endosymbiotic theory predicts a general trend toward clonality, Wolbachia provides an exception in which there is selection to maintain diversity. Here, evolutionary trajectories are discussed that assume that a novel Wolbachia variant will co-exist with the original infection type within a host individual as a superinfection. Relative to prior models, this assumption relaxes requirements and allows additional pathways for the evolution of novel CI types. In addition to describing changes in the Wolbachia infection frequency associated with the hypothesized evolutionary events, the predicted impact of novel CI variants on the host population is also described. This impact, resulting from discordant evolutionary interests of symbiont and host, is discussed as a possible cause of Wolbachia loss from the host population or host population extinction. The latter is also discussed as the basis for an applied strategy for the suppression of insect pest populations. Model predictions are discussed relative to a recently published Wolbachia genome sequence and prior characterization of CI in naturally and artificially infected insects.     

THE DIVERSITY AND EVOLUTION OF BATESIAN MIMICRY IN PAPILIO SWALLOWTAIL BUTTERFLIES

Papilio swallowtail butterflies exhibit a remarkable diversity of Batesian mimicry, manifested in several sex-limited and polymorphic types. There is little understanding of how this diversity is distributed within Papilio , and how different mimicry types have evolved in relation to each other. To answer these questions, I present a graphical model that connects various mimicry types by hypothetical character state changes within a phylogenetic framework. A maximum likelihood analysis of evolution of mimicry types on the Papilio phylogeny showed that sexually monomorphic mimicry and female-limited mimicry have evolved repeatedly but predominantly independently in different clades. However, transitions between these mimicry types are rarely observed. The frequency distribution of character state changes was skewed in favor of the evolution of mimicry, whereas many theoretically plausible character state changes, especially evolutionary loss of mimicry, were not evident. I discuss these findings in relation to studying the tempo of evolutionary change, loss of traits, and directionality and connectivity among character states. The pathway approach and phylogenetic patterns of mimicry demonstrated in Papilio are useful to test novel hypotheses regarding the diversity and evolutionary directionality of Batesian mimicry in other systems.     

血清反应因子结合位点在小鼠及人基因组中保守性、多样性及进化的研究

目的：CArG元件因其为血清反应因子识别的结合位点近年来备受关注。然而迄今为止尚未见到有关CArG元件的序列特征及进化模式的研究。方法：本研究应用生物信息学方法结合遗传学方法对小鼠及人基因组中CArG元件的位置分布序列类型、多样性及保守性进行深入研究。结果：多样性研究结果显示,CArG元件的序列在小鼠及人类基因组存在大量的不同类型。但是,小鼠和人基因组中CArG元件的主要类型又存在明显差异。同源性分析结果表明人类和小鼠中的CArG元件存在两种进化历程,一部分CArG元件拥有共同的祖先,一部分是在物种分化以后突变产生的。结论：上述研究结果将为更为深入阐述SRF的调控模式奠定理论基础,同时为更清楚的阐释CArG元件序列变化对下游基因的表达影响提供理论支持。