相互作用的集合种群研究动态

在集合种群水平上,两个或更多物种可以生活在同一个斑块网络中而没有相互作用.但在很多情况下,种间的相互作用会影响种群的迁移率、灭绝率和侵占率,从而调节相应物种的集合种群动态.这方面的研究主要有集合种群水平上物种之间的竞争、捕食以及在没有任何环境异质性的条件下物种在空间上聚集分布的产生和维持等.综述了近年来关于集合种群水平上的竞争,捕食者和猎物系统以及捕食与复杂空间动态的最新研究成果.     

生境破坏的模式对集合种群动态和续存的影响

构建了空间关联的集合种群模型,该模型不但包含了种群的空间结构信息,而且引入了破坏生境的全局密度和局部密度两个指标,它们描述了破坏生境的模式.模型揭示了破坏生境的空间分布格局复杂地影响了集合种群的动态和续存,破坏和未破坏生境斑块的均匀混合不利于集合种群的增长和续存,而生境类型聚集分布可以促进集合种群的快速增长和长期续存;对于两种斑块类型相对均匀混合的生境来说,均匀场假设可能会高估集合种群的续存,对于相对斑块类型高度聚集的生境,均匀场假设可能会低估集合种群的续存;物种的迁移范围也会影响集合种群的续存,迁移范围越大的物种越容易抵御生境的破坏而免遭灭绝.这意味着在生物保护中不能仅仅考虑生境的恢复和斑块质量的改善,生境结构的构建也是很重要的,加强生境斑块之间的连通性也有利于物种的长期续存.     

流苏石斛(Dendrobium fimbriatum)迁地保护种群的数量动态

运用静态生命表、生殖力表和Leslie矩阵模型,研究了保存于中国科学院西双版纳热带植物园兰科植物迁地保护区中的濒危物种流苏石斛种群数量动态过程,评价了流苏石斛的迁地保护效果.结果表明:迁地保护种群的年龄锥体为壶型锥体,种群的净增长率、内禀增长率和周限增长率较低,种群正处于下降态势;Leslie矩阵模型分析表明,在未来50年内,该种群各龄级的个体数及种群总数均表现出持续下降趋势.模型分析发现:1)迁地保护区模拟生境尽管适宜流苏石斛的生长,但由于附着在树上,中龄级个体先端产生的无性繁殖芽不能及时附着在附主上掉落死亡.因此,需要改善迁地保护区的生境条件,如增加岩石生境(流苏石斛野生种群几乎都是岩生的)使幼龄级个体脱落后能够顺利进入种群;2)种群下降的另一主要原因就是中龄级个体繁殖力太低.因此,建议加强对中龄级个体的管理提高繁殖能力以及深入研究实现种子的就地共生萌发,从根本上实现流苏石斛资源的保护.     

坡向对四川冶勒红豆杉种群分布格局的影响——基于斑块信息的分析

在斑块信息的基础上,利用GIS技术分析了坡向对四川冶勒红豆杉种群分布格局的影响.结果表明,冶勒红豆杉种群主要分布在西北向、东北向、东向和北向斑块上,这些斑块在分布面积、平均斑块大小、平均斑块周长以及红豆杉个体的分布数量方面均占绝对优势.红豆杉种群的分布同坡向之间存在极显著的关联性,种群优先分布于北坡、东北坡、西北坡和东坡斑块,其次为西坡和西南坡斑块,最后为平地和东南坡斑块.冶勒红豆杉种群的分布格局绝大多数为聚集分布(除南向斑块外).其中,种群聚集强度最大的是北向斑块,其CE值高达0.906,其次为东北向、西北向斑块,其CE值分别为0.797和0.563,而其余坡向斑块上的CE值均低于0.5.聚集强度CE值与斑块数量、斑块总周长以及斑块上分布的红豆杉个体数呈显著正相关(相关系数分别为0.936、0.735和0.802),而与斑块面积、平均斑块大小、平均斑块周长、平均形状指数无显著相关.     

华南海岸英罗港红树植物木榄种群结构的空间异质性

采用位置指数(CE)、分异指数(TC和TH)、Shannon-Wiener多样性指数(D)以及Ripley的K-方程,探讨了华南海岸英罗港树植物木榄种群的分布格局、胸转和树高分异以及冠层结构方面的空间异质性.多数种群呈现随机分布,其个体胸转和树高的分异程度较低;页少数种群呈现集群分布,其个体胸围和树高的分异程度明显.采用地理信息(GIS)对冠层和空隙斑块进行了多种水平垂直尺度的分析,冠层与空隙斑块之间的镶嵌格局因种群而异,这种可基于树冠抽影用Shannon-wiener多样性指数时行定量描述.冠层结构的窨异质性阻碍空间尺度而变化,但这种变化在一定尺度范围内保持相对的稳定.迷一尺度范围可作为木榄红树森更新或生态管理单位的参考尺度.     

中国湿地物种多样性与生境面积关系及其生态学机理的模拟研究

生物群落中的物种多样性是群落生态学研究的一个基本问题。大量的实验研究表明物种多样性和生境面积的常数次幂成比例,这说明它们的对数数量级呈线性正相关。我们研究了中国境内15块湿地的高等植物和32块湿地鸟类多样性,发现它们分别和湿地面积在对数尺度上呈线性正相关．进一步支持了种数与面积的幂指数关系。我们还借助计算机模拟系统地讨论了产生这种简单规律的生态学机理,包括中性理论、集合种群动态和物种分布的自相似性。中性理论假设了群落中物种的个体之间只有竞争关系,忽略了其它的种间关系。集合种群动态理论考虑的是由多个亚群落构成的集合群落,在研究种数和面积关系时也忽略了种间关系,所以也是中性的。尽管物种分布的自相似性可导致这种面积幂指数关系,但在自然界中自相似性也可能不成立。     

普通野生稻种群恢复的生态学研究 II.种群动态

以3年的野外调查为基础,通过斑块数量、斑块面积、斑块优势度、斑块的大小分布以及斑块转化等各项指标,研究了茶陵普通野生稻(Oryza rufipogon)种群恢复初期的种群动态。作为人工管理下的自然种群,普通野生稻种群在1997～1999年间持续增加,个体数由447丛增加到803丛,4 m2以上的斑块数由19个增加到31个,斑块总面积由268 m2增加到780 m2,斑块在群落中的优势度值由0.0627增加到0.1148。目前,种群以小斑块（面积小于20 m2）为主,种群的斑块大小分布为增长型分布。在斑块转     

茂兰喀斯特山地广东松种群结构和动态初步研究

 广东松(Pinus kwangtungensis)是国家三类重点保护植物,为贵州茂兰国家自然保护区喀斯特山顶森林群落演替先锋树种和建群种之一。基于大小结构分析法、矩阵模型和分布格局距离方法,对茂兰喀斯特山地广东松种群结构和动态进行了初步研究。结果表明：(1)广东松种群大小结构近倒金字塔形,为中衰至衰退型种群;(2)广东松年龄(E)和胸径(D)的回归方程为E=59.968／(4.041-lnD);(3)广东松种群分布格局为斑块内种群个体集聚分布,斑块个体均匀分布;(4)广东松各径级度的种群密度(DS)随径级度(DG)呈S形变化,DS=1／(0.0584+0.018e-DG);(5)广东松种群为先锋种群,也能在山顶特殊生境中一定时期内与其它种群一起形成稳定群落;(6)分布格局距离方法能有效地用于亚热带森林树种的种群分布格局研究,矩阵模型能在—定程度上反映森林树种种群的数量和结构动态。     

完达山东部地区东北虎主要猎物种群的时空动态模拟

基于能体现直接与间接人为干扰的不同意外死亡率和环境容纳量情景,使用景观尺度的动物种群模型（LAPS）模拟了1990—2009年完达山东部地区东北虎主要猎物种群的时空动态,研究了意外死亡率和环境容纳量对种群动态的影响,并直观展现了研究区内动物集群的时空分布状况,比较了不同生境斑块类型中个体密度的差异.结果表明：意外死亡率对研究区动物种群动态的影响较环境容纳量大;灌丛中动物种群的密度高于阔叶林中的密度.研究结果为有效进行东北虎主要猎物的保护与管理提供了科学依据,但相关的定量验证还需深入研究.     

普通野生稻种群恢复的生态学研究 II.种群动态

 以3年的野外调查为基础,通过斑块数量、斑块面积、斑块优势度、斑块的大小分布以及斑块转化等各项指标,研究了茶陵普通野生稻(Oryza rufipogon)种群恢复初期的种群动态。作为人工管理下的自然种群,普通野生稻种群在1997～1999年间持续增加,个体数由447丛增加到803丛,4 m2以上的斑块数由19个增加到31个,斑块总面积由268 m2增加到780 m2,斑块在群落中的优势度值由0.0627增加到0.1148。目前,种群以小斑块（面积小于20 m2）为主,种群的斑块大小分布为增长型分布。在斑块转     

Variation at a chloroplast minisatellite locus reveals the signature of habitat fragmentation and genetic bottlenecks in the rare orchid Anacamptis palustris (Orchidaceae)

Geoclimatic changes during the Oligocene and more recent anthropogenic influences have shaped the current distribution and population structure of Mediterranean plant species. Anacamptis palustris (Orchidaceae) is a typical member of coastal wetlands, which have become increasingly fragmented and isolated. As a consequence, this orchid has become rare in the recent past. Length variation at a chloroplast minisatellite locus was used to estimate genetic variation within and between the largest extant populations of A. palustris. Genetic diversity was positively correlated with population size. Estimation of observed and expected gene diversity and analyses of haplotype number and haplotype frequency distributions provided evidence for population bottlenecks in the history of small populations. Comparison with an earlier study suggests that nuclear allozyme diversity was most likely lost during the Oligocene and could not recover subsequently due to low mutation rates, whereas genetic variation was restored at the highly variable chloroplast minisatellite locus. Population bottlenecks indicated by cpDNA variation occurred most likely as a consequence of more recent anthropogenic changes. The comparison of molecular markers with different levels of polymorphism provided valuable insights into the processes shaping genetic diversity and population structure in this rare orchid.     

Abundance�Coccupancy relationships in metapopulations: examples of rock pool Daphnia

Intraspecific positive relationships between abundance and occupancy are observed for many species, suggesting that the same processes drive local and regional species dynamics. Two main groups of mechanisms explain this relationship: spatiotemporal variation in local population growth rates due to variation in habitat quality, or dispersal effects that increase occupancy of a species when locally abundant. Several studies show that spatiotemporal variation in population growth rates causes positive abundance?Coccupancy relationships, but few have shown dispersal effects. It is believed that such effects should be more evident for species whose dispersal is limited, e.g. metapopulations, but those studies are limited. This study investigates abundance?Coccupancy relationships in three Daphnia metapopulations in rock pools and the degree to which dispersal or habitat quality affect their local abundances and occurrence. Daphnia longispina and Daphnia magna showed positive abundance?Coccupancy relationships, but not Daphnia pulex. No single ecological factor could explain the abundance?Coccupancy relationships of any given species. Instead, dispersal processes and rock pool quality (mainly salinity and depth) seem to act together to shape the abundance?Coccupancy relationships. Such a conclusion is also supported by an immigration experiment in natural rock pools. This study suggests that although positive abundance?Coccupancy relationships may be commonly found for metapopulations, both dispersal processes and variation in habitat quality can be factors determining the abundance?Coccupancy relationship of metapopulations experiencing habitat heterogeneity.     

Ramet demography of a nurse bromeliad in Brazilian restingas

Restingas are sandy coastal plains that stand between the sea and the Brazilian Atlantic forest mountains. The predominant restinga vegetation type in northern Rio de Janeiro, Brazil, is characterized by the formation of islands that begins with colonization by some pioneer herbs and/or woody plants. Pioneer plants are stress-resistant and nurse many other less-resistant plant species. Determining the spatiotemporal variation in the dynamics of nurse plants is essential to understand the ecological functioning of restingas as a whole. The goal of this study was to analyze the spatiotemporal variation in population dynamics of the nurse bromeliad Aechmea nudicaulis. We monitored A. nudicaulis ramets in different habitats, microhabitats, and years. We analyzed the spatiotemporal variation in demographic traits and in population growth rate. Results showed young ramet traits were more variable at the microhabitat level, and when variable, vegetative ramet traits varied at all spatiotemporal scales. Overall, λ values indicated that A. nudicaulis basically remained spatiotemporally stable as most of the λ values did not significantly differ from unity. Hence, the stability of A. nudicaulis in different microhabitats and habitats in the restinga may create several settlement opportunities for many other less-resistant species.     

兰花花发育的分子生物学研究进展

兰科植物是开花植物中最大的家族之一,其花高度进化,具有花瓣状的萼片,特化的唇瓣和雌雄蕊合生的蕊柱,是单子叶植物花发育生物学研究的理想材料。近年来有关兰花花发育基因调控的研究已取得了一些进展,本文从兰花开花转换和兰花花器官的形成两方面综述了近年来国内外关于兰花花发育分子机理方面的研究进展,主要介绍了文心兰、蝴蝶兰和石斛兰的花发育相关基因,并推测了兰花花被的进化发育过程,认为兰花的DEFICIENS(DEF)类基因在早期经过两轮复制,形成了四类DEF基因,从而促进了花萼与花瓣的分离、侧瓣与唇瓣的分离。该文最后对今后兰花花发育研究的发展方向进行了展望。     

Classification of Orchidaceae in the Age of DNA data

Summary.  The relationships of orchid tribes and subtribes are discussed in the light of recent DNA studies. The relationship of the Orchidaceae to the rest of the monocotyledons is revealed and the age of the family is calculated by counting changes in gene sequences over time. A summary cladogram of orchid relationships based on published DNA studies is given.     

Orchid biology: from Linnaeus via Darwin to the 21st century

Orchidaceae are the largest family of flowering plants, with at least 24 000 species, and perhaps better than any other family of flowering plants, orchids represent the extreme specializations that are possible. As a result, they have long fascinated luminaries of the botanical world including Linnaeus and Darwin, but the size of the family has historically been an impediment to their study. Specifically, the lack of detailed information about relationships within the family made it difficult to formulate explicit evolutionary hypotheses for such a large group, but the advent of molecular systematics has revolutionized our understanding of the orchids. Their complex life histories make orchids particularly vulnerable to environmental change, and as result many are now threatened with extinction. In this Special Issue we present a series of 20 papers on orchid biology ranging from phylogenetics, floral evolutionary development, taxonomy, mycorrhizal associations, pollination biology, population genetics and conservation.     

Genome size variation in Orchidaceae subfamily Apostasioideae: filling the phylogenetic gap

With more than 160‐fold variation, Orchidaceae are currently the most diverse angiosperm family with respect to the amount of nuclear DNA. This study provides first genome size estimates for approximately 50% of species currently recognized in subfamily Apostasioideae, which is sister to the other four orchid subfamilies. The estimated 1C‐values range from 0.38 pg in Apostasia nuda to 5.96 pg in Neuwiedia zollingeri var. javanica, a nearly 16‐fold range. The two genera show non‐overlapping genome sizes, with those in Apostasia being distinctly smaller than those in Neuwiedia. In fact, most Apostasia spp. are at the lower end of the range of orchid C‐values. Observed discontinuities in DNA amounts in genera most probably reflect interspecific variation in ploidy. In addition to ploidy heterogeneity in N. zollingeri var. javanica, intraspecific variation in genome size (up to 17.7%) was also detected in some species; this can be plausibly related to the incidence of different geographical variants or unrecognized taxonomic heterogeneity. The AT content varied from 62.6 to 66.0%, which is in the upper range recorded for angiosperms. The genome size data obtained in this study fill a major phylogenetic gap in Orchidaceae and show that (very) small genomes prevail in subfamily Apostasioideae. © 2013 The Linnean Society of London     

Mycorrhizal diversity in Apostasia (Orchidaceae) indicates the origin and evolution of orchid mycorrhiza

We demonstrated that "orchid mycorrhiza," a specialized mycorrhizal type, appeared in the common ancestor of the largest plant family Orchidaceae and that the fungal partner shifted from Glomeromycota to a particular clade of Basidiomycota in association with this character evolution. Several unique mycorrhizal characteristics may have contributed to the diversification of the family. However, the origin of orchid mycorrhiza and the diversity of mycobionts across orchid lineages still remain obscure. In this study, we investigated the mycorrhizae of five Apostasia taxa, members of the earliest-diverging clade of Orchidaceae. The results of molecular identification using nrDNA ITS and LSU regions showed that Apostasia mycorrhizal fungi belong to families Botryobasidiaceae and Ceratobasidiaceae, which fall within the order Cantharellales of Basidiomycota. Most major clades in Orchidaceae also form mycorrhizae with members of Cantharellales, while the sister group and other closely related groups to Orchidaceae (i.e., Asparagales except for orchids and the "commelinid" families) ubiquitously form symbioses with Glomeromycota to form arbuscular mycorrhizae. This pattern of symbiosis indicates that a major shift in fungal partner occurred in the common ancestor of the Orchidaceae.