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1.
James Rosindell Stephen J. Cornell Stephen P. Hubbell Rampal S. Etienne 《Ecology letters》2010,13(6):716-727
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Gavrilets S Li H Vose MD 《Evolution; international journal of organic evolution》2000,54(4):1126-1134
Abstract. Geographic variation may ultimately lead to the splitting of a subdivided population into reproductively isolated units in spite of migration. Here, we consider how the waiting time until the first split and its location depend on different evolutionary factors including mutation, migration, random genetic drift, genetic architecture, and the geometric structure of the habitat. We perform large-scale, individual-based simulations using a simple model of reproductive isolation based on a classical view that reproductive isolation evolves as a by-product of genetic divergence. We show that rapid parapatric speciation on the time scale of a few hundred to a few thousand generations is plausible even when neighboring subpopulations exchange several individuals each generation. Divergent selection for local adaptation is not required for rapid speciation. Our results substantiates the claims that species with smaller range sizes (which are characterized by smaller local densities and reduced dispersal ability) should have higher speciation rates. If mutation rate is small, local abundances are low, or substantial genetic changes are required for reproductive isolation, then central populations should be the place where most splits take place. With high mutation rates, high local densities, or with moderate genetic changes sufficient for reproductive isolation, speciation events are expected to involve mainly peripheral populations. 相似文献
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Kwaku Aduse‐Poku Freerk Molleman William Oduro Samuel K. Oppong David J. Lohman Rampal S. Etienne 《Ecology and evolution》2018,8(1):296-308
The unified neutral theory of biodiversity and biogeography has gained the status of a quantitative null model for explaining patterns in ecological (meta)communities. The theory assumes that individuals of trophically similar species are functionally equivalent. We empirically evaluate the relative contribution of neutral and deterministic processes in shaping fruit‐feeding butterfly assemblages in three tropical forests in Africa, using both direct (confronting the neutral model with species abundance data) and indirect approaches (testing the predictions of neutral theory using data other than species abundance distributions). Abundance data were obtained by sampling butterflies using banana baited traps set at the forest canopy and understorey strata. Our results indicate a clear consistency in the kind of species or species groups observed at either the canopy or understorey in the three studied communities. Furthermore, we found significant correlation between some flight‐related morphological traits and species abundance at the forest canopy, but not at the understorey. Neutral theory's contribution to explaining our data lies largely in identifying dispersal limitation as a key process regulating fruit‐feeding butterfly community structure. Our study illustrates that using species abundance data alone in evaluating neutral theory can be informative, but is insufficient. Species‐level information such as habitat preference, host plants, geographical distribution, and phylogeny is essential in elucidating the processes that regulate biodiversity community structures and patterns. 相似文献
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Gian Marco Palamara;Alejandro Rozenfeld;Charles N. de Santana;Jan Klecka;Rodrigo Riera;Victor M. Eguíluz;Carlos J. Melián; 《Ecography》2023,2023(7):e06385
Biodiversity can increase in both high- and low-connected landscapes. However, we lack predictions related to biodiversity dynamics when accounting for the temporal heterogeneity in the connections among the habitats of a landscape. Here, we study the relationship between fluctuations in landscape connectivity and biodiversity dynamics at local and regional scales. We contrast predictions about species richness between landscapes with and without fluctuations in connectivity. Our results show that local (α) and regional (γ) richness can increase together in dynamic landscapes characterized by periodic connectivity, clarifying empirical findings of high biodiversity in both low and high-connected landscapes. Our results also suggest that fluctuations in connectivity increase the overall number of species coexisting in dynamic landscapes when compared with static landscapes with no fluctuations in connectivity. Extending metacommunity theory, by including fluctuations in landscape connectivity, can thus provide new testable predictions about species diversity across broad spatiotemporal scales in rapidly changing landscapes. 相似文献
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该文以物种组成较为复杂的青藏高原东部亚高寒草甸为背景,结合最新的群落中性理论,以解释亚高寒草甸草本植物群落的物种分布格局和生物多样性的维持机制。通过对阴坡、阳坡和滩地3个生境进行随机取样调查,用中性模型对所得多样性数据进行拟合,并分别应用置信区间检验、拟合优度检验和多样性指数检验3种方法对拟合效果进行检验。研究结果表明,在拟合优度检验中,3个生境中中性理论预测和实际物种多度分布之间没有显著差异(p>0.05);实际观测值基本全部落入模型预测分布的95%的置信区间之内（仅滩地草本植物群落的63个物种中的1个以及阴坡草本植物群落75个物种中的2个偏离95%的置信区间）;对群落多样性的预测也和实际观测没有显著差异,其中丰富度预测拟合得最好(0.49相似文献
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Aims One major goal of modern community ecology is to understand how deterministic and stochastic processes combine to drive community assembly. However, little empirical knowledge is known about how their relative importance varies between common and rare species.Methods We exploited two 30-year data sets of plant communities in a temperate steppe using two different methods. One is a null model method, and the other is a recently developed direct-calculation method.Important findings We found that stochastic processes tended to be more important in influencing rare than common species. This finding suggests that stochastic forces may play a more important role in structuring communities with more rare species, providing a possible solution to the debate on the varied importance of deterministic and stochastic processes among different communities. 相似文献
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Published in 2001, The Unified Neutral Theory of Biodiversity and Biogeography (UNTB) emphasizes the importance of stochastic processes in ecological community structure, and has challenged the traditional niche‐based view of ecology. While neutral models have since been applied to a broad range of ecological and macroecological phenomena, the majority of research relating to neutral theory has focused exclusively on the species abundance distribution (SAD). Here, we synthesize the large body of work on neutral theory in the context of the species abundance distribution, with a particular focus on integrating ideas from neutral theory with traditional niche theory. First, we summarize the basic tenets of neutral theory; both in general and in the context of SADs. Second, we explore the issues associated with neutral theory and the SAD, such as complications with fitting and model comparison, the underlying assumptions of neutral models, and the difficultly of linking pattern to process. Third, we highlight the advances in understanding of SADs that have resulted from neutral theory and models. Finally, we focus consideration on recent developments aimed at unifying neutral‐ and niche‐based approaches to ecology, with a particular emphasis on what this means for SAD theory, embracing, for instance, ideas of emergent neutrality and stochastic niche theory. We put forward the argument that the prospect of the unification of niche and neutral perspectives represents one of the most promising future avenues of neutral theory research. 相似文献
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Da-Yong Zhang Bo-Yu Zhang Kui Lin Xinhua Jiang Yi Tao Stephen Hubbell Fangliang He Annette Ostling 《Journal of Plant Ecology》2012,5(1):82
Aims Much recent theory has focused on the role of neutral processes in assembling communities, but the basic assumption that all species are demographically identical has found little empirical support. Here, we show that the framework of the current neutral theory can easily be generalized to incorporate species differences so long as fitness equivalence among individuals is maintained through trade-offs between birth and death.Methods Our theory development is based on a careful reformulation of the Moran model of metacommunity dynamics in terms of a non-linear one-step stochastic process, which is described by a master equation.Important findings We demonstrate how fitness equalization through demographic trade-offs can generate significant macroecological diversity patterns, leading to a very different interpretation of the relation between Fisher's α and Hubbell's fundamental biodiversity number. Our model shows that equal fitness (not equal demographics) significantly promotes species diversity through strong selective sieving of community membership against high-mortality species, resulting in a positive association between species abundance and per capita death rate. An important implication of demographic trade-off is that it can partly explain the excessively high speciation rates predicted by the neutral theory of the stronger symmetry. Fitness equalization through demographic trade-offs generalizes neutral theory by considering heterospecific demographic difference, thus representing a significant step toward integrating the neutral and niche paradigms of biodiversity. 相似文献
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群落构建的中性理论和生态位理论 总被引：20，自引：1，他引：20
物种共存和生物多样性维持一直是生态学研究的中心论题。基于物种生态位分化的群落构建理论已经发展了近一个世纪, 但我们对群落构建和生物多样性维持的机理仍然不清楚。近年来, 群落中性理论以其简约性和预测能力成为群落生态学研究的焦点, 但由于其“物种在生态功能上等价”的假设与大量研究结果相悖, 同时对自然群落结构的准确预测也只限于少数的生态系统, 因而饱受质疑。如今, 越来越多的生态学家认为群落构建的生态位理论与中性理论之争的最终归宿应该是二者的整合。 在本文中, 我们在简要回顾生态位理论和群落中性理论发展的基础上, 分析二者之间的主要分歧和互补性, 试图梳理二者整合的途径。我们认为, 尽管中性理论的发展极大地丰富了群落构建理论, 但二者的整合尚处于初级阶段; 群落构建零模型假说、中性—生态位连续体假说、随机生态位假说等都不失为有价值的尝试, 今后需要在其他类型的生态系统中进行实验验证, 以更好地理解确定性过程和随机过程在决定群落构建和生物多样性维持中的作用。 相似文献
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Jobst Pfaender Renny K. Hadiaty Ulrich K. Schliewen Fabian Herder 《Proceedings. Biological sciences / The Royal Society》2016,283(1822)
Strong disruptive ecological selection can initiate speciation, even in the absence of physical isolation of diverging populations. Species evolving under disruptive ecological selection are expected to be ecologically distinct but, at least initially, genetically weakly differentiated. Strong selection and the associated fitness advantages of narrowly adapted individuals, coupled with assortative mating, are predicted to overcome the homogenizing effects of gene flow. Theoretical plausibility is, however, contrasted by limited evidence for the existence of rugged adaptive landscapes in nature. We found evidence for multiple, disruptive ecological selection regimes that have promoted divergence in the sympatric, incipient radiation of ‘sharpfin’ sailfin silverside fishes in ancient Lake Matano (Sulawesi, Indonesia). Various modes of ecological specialization have led to adaptive morphological differences between the species, and differently adapted morphs display significant but incomplete reproductive isolation. Individual fitness and variation in morphological key characters show that disruptive selection shapes a rugged adaptive landscape in this small but complex incipient lake fish radiation. 相似文献
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- Stump extraction for bio energy is a new forestry activity and before large‐scale implementation occurs, it is important to analyse its consequences. Saproxylic beetles depend on dead trees and stump extraction will reduce the amount of habitat available for this group.
- Early warning signs of impending regional species extinctions were looked for in areas where stump harvest has only been conducted for about 3 years. In a paired design (N = 8), the beetle fauna was sampled in stumps on ordinary clear‐cuts and on clear‐cuts from which stumps had been extracted. Sampling in extraction clear‐cuts was possible because 25% of the stump volume was retained. Samples were collected by bark sieving ten Norway spruce, Picea abies, stumps per clear‐cut.
- In total, 6959 individuals of 46 species were found. Several early warning signs were seen: stump extraction reduced the number of species per stump and per clear‐cut and reduced the species evenness in individual stumps.
- Species at higher trophic levels (predators and fungivores), in particular, suffered negative effects. Stump extraction reduced the number of species of fungivores and facultative predators/fungivores at the clear‐cut level and reduced the relative abundance of predators at the stump level.
- These results indicate that if stumps are extracted from a high proportion of the clear‐cuts in a region, the present recommendations of leaving 15–25% of the stump volume will be insufficient for preserving the beetle fauna in the stumps. Further studies are needed to identify levels of stump retention that do not lead to species loss.
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Dean Ansell Graham Fifield Nicola Munro David Freudenberger Philip Gibbons 《Restoration Ecology》2016,24(2):159-164
The loss and degradation of woody vegetation in the agricultural matrix represents a key threat to biodiversity. Strategies for habitat restoration in these landscapes should maximize the biodiversity benefit for each dollar spent in order to achieve the greatest conservation outcomes with scarce funding. To be effective at scale, such strategies also need to account for the opportunity cost of restoration to the farmer. Here, we critique the Whole‐of‐Paddock Rehabilitation program, a novel agri‐environment scheme which seeks to provide a cost‐effective strategy for balancing habitat restoration and livestock grazing. The scheme involves the revegetation of large (minimum 10 ha) fields, designed to maximize biodiversity benefits and minimize costs while allowing for continued agricultural production. The objectives and design of the scheme are outlined, biodiversity and production benefits are discussed, and we contrast its cost‐effectiveness with alternative habitat restoration strategies. Our analysis indicates that this scheme achieves greater restoration outcomes at approximately half the cost of windbreak‐style plantings, the prevailing planting configuration in southeastern Australia, largely due to a focus on larger fields, and the avoidance of fencing costs through the use of existing farm configuration and infrastructure. This emphasis on cost‐effectiveness, the offsetting of opportunity costs through incentive payments, and the use of a planting design that seeks to maximize biodiversity benefits while achieving production benefits to the farmer, has the potential to achieve conservation in productive parts of the agricultural landscape that have traditionally been “off limits” to conservation. 相似文献
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Vascular epiphytes form a diverse group of almost 30 000 species, yet theory concerning their community structure is still largely lacking. We therefore employed the simplest models of biodiversity, (near-)neutral models, to generate hypotheses concerning their community structure. With recently developed tools for (near-)neutral models we analyzed species abundance data from many samples in Central and South America which we divided into four metacommunities (Mesoamerica, Central America, Amazonia and Paraná), where for each metacommunity we considered two subsets differing in dispersal syndrome: an animal-dispersed guild and a wind-dispersed guild. We considered three models differing in the underlying speciation mode. Across all metacommunities, we found observed patterns to be indistinguishable from patterns generated by neutral or near-neutral processes. Furthermore, we found that subdivision in different dispersal guilds was often supported, with recruitment limitation being stronger for animal-dispersed species than for wind-dispersed species. This is the first time that (near-)neutral theory has been applied to epiphyte communities. Future efforts with additional data sets and more refined models are expected to further improve our understanding of community structure in epiphytes and will have to test the generality of our findings. 相似文献
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John M. Halley Vasiliki Sgardeli Kostas A. Triantis 《Global Ecology and Biogeography》2014,23(1):113-123
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Four cruises of survey were carried out in the Beibu Gulf between Feb 1998 and May 1999. A total of 18 species of planktonic Ostracoda were identified, including Cypridina nana, Cypridina dentata, Cypridina acuminata, Cypridina nami, Euconchoecia aculeata, Euconchoecia elongata, Euconchoecia maima, and other taxa. Planktonic Ostracoda in the gulf were divided into three ecological types: (1) a hyposaline and warm-water group, (2) a eurythermal and eurysaline group, and (3) a hyperthermal and hysaline group. The warm water species such as Euconchoecia aculeate and Cypridina acuminate were the dominant Ostracoda species in the gulf, where the overall Ostracoda density ranged from 0.02 ind./m3 to 51.58 ind./m3 and averaged 1.22 ind./m3. The highest average value (2.73 ind./m3) was found in spring. Fuzzy evaluation measures indicated that the diversity in the gulf remained low (level of class I) during all seasons. Diversity appeared to be relatively higher in some regions in which the water mass was strongly influenced by the open sea and had complex structures. This article also discusses how the species composition, abundance and diversity of planktonic Ostracoda are influenced by environmental factors (e.g., aquatic system, water mass, water temperature and salinity) in the Beibu Gulf. 相似文献
18.
The mechanisms responsible for latitudinal biodiversity gradients have fascinated and perplexed biologists since the time of Darwin. Ecological theory has yielded two general classes of mechanisms to account for variation in biodiversity: dispersal–assembly mechanisms that invoke differences in stochastic rates of speciation, extinction and dispersal; and niche–assembly mechanisms that invoke species differences, species interactions and environmental heterogeneity. Distinguishing between these two classes of mechanisms requires explicit consideration of macroevolutionary dynamics. Here, we assess the importance of dispersal–assembly mechanisms in the origin and maintenance of biodiversity using fossil data that encompass 30 million years of macroevolution for three distinct groups of ocean plankton: foraminifera, nannoplankton and radiolaria. Applying new methods of analysis to these fossil data, we show here for the first time that latitudinal biodiversity gradients exhibit strong positive correlations with speciation rates even after explicitly controlling for variation in sampling effort and for increases in habitat area towards the equator. These findings provide compelling evidence that geographical variation in macroevolutionary dynamics is a primary determinant of contemporary biodiversity gradients, as predicted by dispersal–assembly theory. 相似文献
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根据1998年1月～1999年5月北部湾海域4个航次生态环境综合调查资料,对北部湾海域浮游介形类进行分析研究。结果表明,北部湾渔场浮游介形类物种组成较为简单,记录有小型海萤（Cypridina nana）、齿形海萤（Cypridina dentata）、尖尾海萤（Cypridina acuminata）、纳米海萤（Cypridina nami）、针刺真浮萤（Euconchoecia aculeata）、细长真浮萤（Euconchoecia elongata）、后圆真浮萤（Euconchoecia maimai）等18种;隶属于2亚目、2科、4亚科、12属,其中有4种周年出现,9种只在特定的单一季节出现,其余5种季节性出现;夏季和冬季出现的物种数最多,达到11种;春季次之,为9种;秋季最少,只有6种。北部湾浮游介形类可以划分为3个生态类群,即低盐暖水类群、广温广盐类群和高温高盐类群,优势种群主要是近岸低盐暖水类群的针刺真浮萤和尖尾海萤。全海域栖息密度变化范围为0．02～51．58ind．／m^3,年平均1．22ind．／m^3,春季最高,达2．73ind．／m^3,在湾西北部密集有大量的针刺真浮萤;夏季此密集区逐渐向湾中部移动,纳米海萤为其密集种,栖息密度也有所降低;秋、冬季量少,但在湾南、北部各出现一个丰度相对较高的密集区,并由南北向湾中部递减。总生物量具有明显的季节性变化,平面分布趋势与栖息密度相似。生物多样性指数低,以湾口较高、湾顶较低,呈湾口向湾内西北方向递减趋势;全海域年平均多样性阈值为0．329,四季多样性水平皆为Ⅰ级,多样性程度低;多样性程度较高的区域,多出现于受外海水影响较大、水文状况变化较为复杂的海域。对浮游介形类的物种组成、丰度分布及多样性与北部湾的水系、水团、水温及盐度等环境因子的关系进行了探讨。 相似文献