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31.
Background and AimsHybridization is the main driver of plant diversification, and gene flow via hybridization has multifaceted effects on plant evolution. Carex angustisquama is an extremophyte that grows on soils heavily acidified by volcanism. Despite its habitat distinct from that of other species, this species is known to form interspecific hybrids, implying interspecific gene flow. It is crucial to verify the extent and direction of interspecific gene flow between C. angustisquama and closely related species to understand the evolutionary process of an extremophyte in solfatara fields.MethodsIn this study, expressed sequence tag–simple sequence repeat markers were utilized to infer the extent and direction of interspecific gene flow between C. angustisquama and closely related species.Key ResultsBayesian clustering and simulation analyses revealed that all individuals of the three hybrid species were classified into the first hybrid generation or first backcross to C. angustisquama; therefore, current interspecific gene flow is limited. Moreover, in the Bayesian inference of historical gene flow based on multispecies samples, the model that assumed no interspecific gene flow was the most strongly supported across all species pairs, including phylogenetically close but ecologically distinctive species pairs.ConclusionsOur results revealed that interspecific gene flow between C. angustisquama and its related species has been limited both currently and historically. Moreover, our results of Bayesian inference of historical gene flow indicated that extrinsic, rather than intrinsic, factors probably act as isolating barriers between Carex species, with hybrid breakdown via microhabitat segregation being the probable potential barrier. Overall, our findings provide insights into the evolutionary process of an extremophyte in solfatara fields and offer an important example of the mechanisms of diversification of the speciose genus Carex.  相似文献   
32.
高敏敏  万凌凡  马燕天  邹锋  何亮  刘以珍  葛刚 《生态学报》2018,38(21):7679-7687
为了揭示鄱阳湖湿地活体植物和自然枯落物在水淹条件下分解过程的差异,以鄱阳湖湿地优势植被物种灰化薹草(Carex cinerascens)和虉草(Phalaris arundinacea)为研究对象,采用分解袋法开展室内模拟实验。植物样品设置新鲜和风干两种处理,分别模拟活体植物和自然枯落物在水下的分解过程。研究结果表明:(1)在180 d的淹水实验过程中,两种处理下的灰化薹草和虉草的分解过程都具有阶段性,前期分解速率较快,后期较慢。(2)两种植物枯落物的分解速率与植物C/N比有显著相关性,而活体植物的分解速率与植物C/N比相关性不强。(3)活体植物和自然枯落物的水下分解速率与物种有关,虉草活体比虉草枯落物分解速率快,而薹草活体比薹草枯落物分解速率慢。(4)模拟实验结束时活体植物仍有34%—43%未分解,推测鄱阳湖丰水期退水后大量洲滩植被消失的原因并非是植被在水淹下完全分解,而是一部分植被被水生动物啃噬或被水流冲走。  相似文献   
33.
以白桦、日阴菅及其它主要草本植物的个体数量为指标,分析了各植物种群在土壤有机质,速效P和pH值3个资源维上的生态位宽度和生态位重叠及其在不同海拔条件下的变化规律。日阴菅生态位宽度随海拔升高而增大,其余植物种类在有机质资源维上的生态位宽度,大都是以中等海拔(800m)的样带最宽,而在速效P资源维上,又以中等海拔的样带为最窄,由于高海拔及相应低气温在某种程度上限制了植物种群在土壤有机质和速效P的利用,主要植物种对之间在这两个资源维上的生态位重叠以高海拔(950m)样带为最小,在土壤pH值资源维上,溪荪与其它主要植物种间的生态位重叠皆以低海拔(650m)样带为最小,可能是其特殊的环境组合迫使溪荪发生了生态位移动,大多数种对在土壤有机质,速效P和pH值3个资源维上都以海拔800m的样带生态位重叠最大。  相似文献   
34.
Carr vegetation was once extensive in New Zealand. It can be divided into Cordyline australis I Carex secta carr, comprising an open wood with scattered large herbs and an abundance of Carex species, and podocarp carr, dominated by tall conifers. Both have been almost eliminated by agricultural development. We studied a remnant of Cordyline australis I Carex secta carr in South Island, which graded at one end into salt marsh. Eight communities were recognized, including one pure salt marsh and two more with saline influence. Near the stream that provided moisture and alluvium for the area were herbaceous communities. In the poorly-drained area away from the stream were communities dominated by shrubs and small trees. The soil environment is similar to that of many European carrs, though generally less organic. A number of the exotic species are also found in European carrs.  相似文献   
35.
Carex sect. Confertiflorae s.l. is a medium-sized species group (ca. 40 species) with its center of diversity in E Asia (China and Japan). According to morphological traits, the section has been proposed to split into two sections (sects. Confertiflorae sensu Ohwi and Molliculae Ohwi) up to five different ones (sects. Confertiflorae s.s., Molliculae, Dispalatae Ohwi, Ischnostachyae Ohwi, and Alliiformes Akiyama). Recent phylogenetic reconstructions showed Confertiflorae s.l. not to be monophyletic, as species traditionally considered part of it were found to belong to other clades, whereas species traditionally ascribed to other sections were nested within it. In this study, we investigated the phylogenetic structure, morphological affinities, and biogeographic history of sect. Confertiflorae s.l. We employed a taxon-based approach to explore the morphological affinities of the species considered in sect. Confertiflorae and compared the micromorphology of the nutlets of almost all the taxa using SEM. We included 40 samples representing 31 species/subspecies of sect. Confertiflorae s.l. and used two nuclear (ETS and ITS) and three plastid (trnL-F, matK, and rpl32-trnL UAG) molecular markers to reconstruct the phylogeny of the group. The phylogenetic analyses confirmed the polyphyly of sect. Confertiflorae s.l., whose representatives were found within five distinct clades. From these, two clades, sect. Confertiflorae and sect. Molliculae, were found to be closely related and contained the majority of the species. The composition of the two clades agreed with the morphological structure of the group, and we confirmed an exclusive combination of features (namely color of basal sheaths, presence of bract sheath, peduncle of lowest spike, inflorescence sex distribution, shape of pistillate glume apex, and color and veins of utricle, among others) characterizing each of the two clades. The origin of the two clades was found to be in the early Pliocene; however, the majority of the diversification events within each clade took place during the Pleistocene. This illustrates that although Asia has been regarded as having little potential ecological space for Carex to diversify due to its climate stability, groups of sedges sub-endemic from that area may have a fairly recent origin related to glaciations. We proposed the rearrangement of sect. Confertiflorae as previously conceived as three independent sections: the monotypic Alliiformes, sect. Molliculae, and sect. Paludosae.  相似文献   
36.
Studies on the rhizomatous clonal sedge Carex bigelowii , at a fellfield site in subarctic Swedish Lapland examined the ecological potential of rhizomes as nitrogen uptake systems. Direct application of a solution of 15NH415NO3 to the rhizomes of C. bigelowii significantly enriched the 15N content of the plant tissue. The pattern of enrichment indicated movement of labelled nitrogen into rhizomes and adjoining tissue (including roots and shoots), showing both uptake and translocation via the rhizome system. There was a gradient of decreasing 15N enrichment with increasing distance from the point of labelling, and estimation of the total mass of nitrogen taken up via labelled rhizomes showed low levels and rates of uptake. Quantification of the size of rhizome and root systems of C. bigelowii at the study site indicates that 80% of the living biomass may be below ground, and that the surface area of the rhizome system of C. bigelowii is approx. two-thirds that of the roots. The rhizome system of C. bigelowii can therefore act as a route for nitrogen uptake, with the potential to exploit almost as great a volume of soil as the root system. This mechanism of nitrogen uptake may play an important role in the Arctic, where many species have a clonal, rhizomatous growth form. In addition, plant growth in many arctic ecosystems is limited by low soil nutrient availability, a result of low temperatures (leading to slow soil decomposition rates) and patchy resource distribution. Nitrogen uptake via rhizomes may provide plants with the capacity to take advantage of transient nutrient supplies, and may partly compensate for the cost of developing and maintaining persistent rhizome networks in ecosystems where nutrient resources are in short supply.  相似文献   
37.
38.
中国薹草属黑穗薹草组的数量分类研究   总被引:1,自引:0,他引:1  
对中国薹草属黑穗薹草组Sect.Racemosae及外类群冻原薹草组Sect.Frigidae共20种3变种采用38个形态特征进行了数量分类研究。聚类分析结果表明,黑穗薹草组应是一个自然分类群;支持了《中国植物志》将两对相似种:乌拉草(Carer meyeriana)与红原薹草(Carer hongyuanensis)、膨囊薹草(Carex lehmanii)与五台山薹草(Carex montis-wutaii)分别处理为种的观点。主成分分析结果表明,本组的分类特征较为稳定与集中,本组主成分分析散点图与聚类分析的分类结果大致吻合,并表明有关小坚果、果囊、鳞片、主茎叶和苞片的性状在本组的分类中起到了主要作用。  相似文献   
39.
Integrating research and practice is a fundamental challenge for restoration and conservation. Scientists recognize restoration as an opportunity to test basic ecological principles, and that core scientific practices such as establishing control plots, replication, monitoring, and data management are fundamental to learning from restoration and management. However, practical constraints inherent to many projects often work against fully integrating research and management. In 2005, we had the opportunity to evaluate a lowland savanna that had been undergoing restoration by The Nature Conservancy since 1997. We used the data generated as a case study to evaluate how the restoration process might have changed had scientists been involved from the outset. Prescribed fire is the primary tool used to restore upland savanna and was chosen by The Nature Conservancy to manage the lowland savanna. In open areas dominated by Reed canary grass (Phalaris arundinacea), fire was associated with reduced cover of this highly invasive species and an increase in native species richness. However, other results suggested that management options beyond the use of fire are needed to restore this lowland savanna. In retrospect, an approach that integrated the skills of researchers and managers at the outset of the study would have altered many of the restoration goals and processes. Pretreatment data, greater replication, and systematically varying treatments could have provided a more robust assessment of treatment effects. We recognize, however, that impediments in staffing, funding, and time were barriers to following this course of action.  相似文献   
40.
Spatial patterns are a subfield of spatial ecology, and these patterns modify the temporal dynamics and stability properties of population densities at a range of spatial scales. Localized ecological interactions can generate striking large-scale spatial patterns in ecosystems through spatial self-organization. Possible mechanisms include oscillating consumer–resource interactions, localized disturbance–recovery processes, and scale-dependent feedback. However, in this paper, our main aim is to study the effect of tide on the pattern formation of a spatial plant-wrack model. We discuss the changes of the wavelength, wave speed, and the conditions of the spatial pattern formation, according to the dispersion relation formula. Both the mathematical analysis and numerical simulations reveal that the tide has great influence on the spatial pattern. More specifically, typical traveling spatial patterns can be obtained. Our obtained results are consistent with the previous observation that wracks exhibit traveling patterns, which is useful to help us better understand the dynamics of the real ecosystems.  相似文献   
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