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Plant invasions and the niche 总被引：1，自引：0，他引：1
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Theo L. Gibbs;Gabriel Gellner;Simon A. Levin;Kevin S. McCann;Alan Hastings;Jonathan M. Levine; 《Ecology letters》2024,27(6):e14458
Most ecological models are based on the assumption that species interact in pairs. Diverse communities, however, can have higher-order interactions, in which two or more species jointly impact the growth of a third species. A pitfall of the common pairwise approach is that it misses the higher-order interactions potentially responsible for maintaining natural diversity. Here, we explore the stability properties of systems where higher-order interactions guarantee that a specified set of abundances is a feasible equilibrium of the dynamics. Even these higher-order interactions which lead to equilibria do not necessarily produce stable coexistence. Instead, these systems are more likely to be stable when the pairwise interactions are weak or facilitative. Correlations between the pairwise and higher-order interactions, however, do permit robust coexistence even in diverse systems. Our work not only reveals the challenges in generating stable coexistence through higher-order interactions but also uncovers interaction patterns that can enable diversity. 相似文献
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Historical contingency broadly refers to the proposition that even random historical events can constrain the ecological and evolutionary pathways of organisms and that of entire communities. Focusing on communities, these pathways can be reflected into specific structural changes within and across trophic levels – how species interact with and affect each other – which has important consequences for species coexistence. Using the registry of the last 2000 years of plant introductions and their novel herbivores encountered in Central Europe, we find that the order of arrival of closely related (but not of distantly related) plant species constrained the structural changes within the trophic level formed by herbivore species across the observation period. Because it is difficult for field and lab experiments to be conducted over hundreds of years to record and replay the assembly history of a community, our study provides an alternative to understand how structural changes have occurred across extensive periods of time. 相似文献
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Many attempts have been made to confirm or reject the unimodal relationship between disturbance and diversity stated by the intermediate disturbance hypothesis (IDH). However, the reasons why the predictions of the IDH apply or fail in particular systems are not always obvious. Here, we use a spatially explicit, individual-based community model that simulates species coexistence in a landscape subjected to disturbances to compare diversity-disturbance curves of communities with different coexistence mechanisms: neutrality, trade-off mechanism and intraspecific density dependence. We show that the shape of diversity-disturbance curves differs considerably depending on the type of coexistence mechanism assumed: (1) Neutral communities generally show decreasing diversity-disturbance curves with maximum diversity at zero disturbance rates contradicting the IDH, whereas trade-off communities generally show unimodal relationships confirming the IDH and (2) density-dependent mechanisms do increase the diversity of both neutral and trade-off communities. Finally, we discuss how these mechanisms determine diversity in disturbed landscapes. 相似文献
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Modern coexistence theory (MCT) is one of the leading methods to understand species coexistence. It uses invasion growth rates—the average, per-capita growth rate of a rare species—to identify when and why species coexist. Despite significant advances in dissecting coexistence mechanisms when coexistence occurs, MCT relies on a ‘mutual invasibility’ condition designed for two-species communities but poorly defined for species-rich communities. Here, we review well-known issues with this component of MCT and propose a solution based on recent mathematical advances. We propose a clear framework for expanding MCT to species-rich communities and for understanding invasion resistance as well as coexistence, especially for communities that could not be analysed with MCT so far. Using two data-driven community models from the literature, we illustrate the utility of our framework and highlight the opportunities for bridging the fields of community assembly and species coexistence. 相似文献
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物种共存机制是群落生态学研究的核心问题之一,但以成对物种间直接相互作用为主的传统共存理论,并未在实际群落中得到普遍证实。近年来,有研究表明,高阶相互作用,即一个物种对另一个物种的直接作用强度受到其他物种的间接影响,在群落竞争过程中的重要性不断得到发展。目前,对高阶相互作用的理论研究还主要集中在非空间理论模型。事实上,群落中个体的空间分布和扩散模式等对种群动态的影响均至关重要。故考虑空间因素,以三物种为例构建空间显式的群落动态模拟,通过引入不同的物种扩散模式,研究高阶相互作用对群落物种共存结果的影响。研究表明：(1)高阶相互作用可以促进也可能抑制物种共存,具体共存结果取决于高阶相互作用的方向、强度和分类;(2)当全部高阶相互作用都存在,且取值为正时,物种共存位置会发生偏移,原本生态位分化下共存的区域不再共存,而在生态位重叠度较高的区域,物种可以在更大范围的适合度差异下共存;(3)扩散模式对高阶相互作用的上述调节机制有一定的影响,且无论正高阶还是负高阶,当种群趋于局部扩散时,高阶相互作用的正向及负向调节效果均有所减弱。以上结论强调了在理论模型和实际保护工作中考虑相互作用网络的重要性,有助于进一步理解物种共存机制,能够为保护生物多样性提供理论依据。 相似文献
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Thomas Banitz 《Oikos》2019,128(10):1478-1491
Trait variation within populations is an important area of research for empirical and theoretical ecologists. While differences between individuals are doubtlessly ubiquitous, their role for species coexistence is much less clear and highly debated. Both unstructured (random) and structured (linked to space, time or inheritance) intraspecific trait variation (ITV) may modify species interactions with nontrivial consequences for emerging community compositions. In many ecosystems, these compositions are further driven by prevalent disturbance regimes. I therefore explored the effects of unstructured as well as spatially structured ITV under disturbances in a generic ecological model of competing sessile species. Using spatially explicit, individual‐based simulations, I studied how intraspecific variation in life history traits together with interspecific tradeoffs and disturbance regimes shape long‐term community composition. I found that 1) unstructured ITV does not affect species coexistence in the given context, 2) spatially structured ITV may considerably increase coexistence, but 3) spatially clumped disturbances reduce this effect of spatially structured ITV, especially if interspecific tradeoffs involve dispersal distance. The findings suggest that spatially structured ITV with individual trait responses to local habitat conditions differing among species may create or expand humps in disturbance–diversity relationships. Hence, if present, these forms of spatially structured ITV should be included in ecological models and will be important for reliably assessing community responses to environmental heterogeneity and change. 相似文献
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Evan C. Johnson;Alan Hastings; 《Oikos》2022,2022(12):e09266
How do species coexist? A framework known as modern coexistence theory can ‘measure coexistence' by partitioning invasion growth rates into coexistence mechanisms, terms which correspond to classes of explanations for coexistence. There are several reasonable ways to define coexistence mechanisms, each depending on exactly how a species perturbed to low density (the invader) is compared to other species that remain at their typical densities (the residents). Using conceptual arguments and two case studies, we compare five methods for calculating coexistence mechanisms: 1) scaling factors, the traditional approach which attempts to eliminate the linear effects of regulating factors; 2) the simple comparison, which gives equal weight to all resident species; 3) generation time scaling, a novel method which corrects for intrinsic differences in population-dynamical speed; 4) β scaling, where resident growth rates are scaled by a measure of relative sensitivity to competition; and 5) the invader–invader comparison, a previously obscure method in which a focal species is compared to itself at high versus low density. We find that the conventional scaling factors can lead to nonsensical results when species have strong and asymmetric niche differences; though scaling factors can be useful in certain theoretical studies, they are not recommended for explaining coexistence in real communities. Invader–invader comparisons are also problematic, as they do not effectively measure specialization or niche differentiation. The universally-applicable simple comparison often works well, but can give counterintuitive results when species have disparate generation times. The β scaling method often works well in simple models, but faces implementation problems in complex models. We tentatively recommend generation time scaling as the all-purpose method for calculating coexistence mechanisms. 相似文献
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Malyon D. Bimler;Daniel B. Stouffer;Trace E. Martyn;Margaret M. Mayfield; 《Ecology letters》2024,27(2):e14376
Species interactions are key drivers of biodiversity and ecosystem stability. Current theoretical frameworks for understanding the role of interactions make many assumptions which unfortunately, do not always hold in natural, diverse communities. This mismatch extends to annual plants, a common model system for studying coexistence, where interactions are typically averaged across environmental conditions and transitive competitive hierarchies are assumed to dominate. We quantify interaction networks for a community of annual wildflowers in Western Australia across a natural shade gradient at local scales. Whilst competition dominated, intraspecific and interspecific facilitation were widespread in all shade categories. Interaction strengths and directions varied substantially despite close spatial proximity and similar levels of local species richness, with most species interacting in different ways under different environmental conditions. Contrary to expectations, all networks were predominantly intransitive. These findings encourage us to rethink how we conceive of and categorize the mechanisms driving biodiversity in plant systems. 相似文献
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Eva Delmas Mathilde Besson Marie‐Hlne Brice Laura A. Burkle Giulio V. Dalla Riva Marie‐Jose Fortin Dominique Gravel Paulo R. Guimares David H. Hembry Erica A. Newman Jens M. Olesen Mathias M. Pires Justin D. Yeakel Timothe Poisot 《Biological reviews of the Cambridge Philosophical Society》2019,94(1):16-36
Network approaches to ecological questions have been increasingly used, particularly in recent decades. The abstraction of ecological systems – such as communities – through networks of interactions between their components indeed provides a way to summarize this information with single objects. The methodological framework derived from graph theory also provides numerous approaches and measures to analyze these objects and can offer new perspectives on established ecological theories as well as tools to address new challenges. However, prior to using these methods to test ecological hypotheses, it is necessary that we understand, adapt, and use them in ways that both allow us to deliver their full potential and account for their limitations. Here, we attempt to increase the accessibility of network approaches by providing a review of the tools that have been developed so far, with – what we believe to be – their appropriate uses and potential limitations. This is not an exhaustive review of all methods and metrics, but rather, an overview of tools that are robust, informative, and ecologically sound. After providing a brief presentation of species interaction networks and how to build them in order to summarize ecological information of different types, we then classify methods and metrics by the types of ecological questions that they can be used to answer from global to local scales, including methods for hypothesis testing and future perspectives. Specifically, we show how the organization of species interactions in a community yields different network structures (e.g., more or less dense, modular or nested), how different measures can be used to describe and quantify these emerging structures, and how to compare communities based on these differences in structures. Within networks, we illustrate metrics that can be used to describe and compare the functional and dynamic roles of species based on their position in the network and the organization of their interactions as well as associated new methods to test the significance of these results. Lastly, we describe potential fruitful avenues for new methodological developments to address novel ecological questions. 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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Sebastian J. Schreiber 《Biology letters》2022,18(7)
For species primarily regulated by a common predator, the P* rule of Holt & Lawton (Holt & Lawton, 1993. Am. Nat. 142, 623–645. (doi:10.1086/285561)) predicts that the prey species that supports the highest mean predator density (P*) excludes the other prey species. This prediction is re-examined in the presence of temporal fluctuations in the vital rates of the interacting species including predator attack rates. When the fluctuations in predator attack rates are temporally uncorrelated, the P* rule still holds even when the other vital rates are temporally auto-correlated. However, when temporal auto-correlations in attack rates are positive but not too strong, the prey species can coexist due to the emergence of a positive covariance between predator density and prey vulnerability. This coexistence mechanism is similar to the storage effect for species regulated by a common resource. Negative or strongly positive auto-correlations in attack rates generate a negative covariance between predator density and prey vulnerability and a stochastic priority effect can emerge: with non-zero probability either prey species is excluded. These results highlight how temporally auto-correlated species’ interaction rates impact the structure and dynamics of ecological communities. 相似文献
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Heather A. Berkley Bruce E. Kendall Satoshi Mitarai David A. Siegel 《Ecology letters》2010,13(3):360-371
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Thomas C. Ings José M. Montoya Jordi Bascompte Nico Blüthgen Lee Brown Carsten F. Dormann François Edwards David Figueroa Ute Jacob J. Iwan Jones Rasmus B. Lauridsen Mark E. Ledger Hannah M. Lewis Jens M. Olesen F.J. Frank van Veen Phil H. Warren Guy Woodward 《The Journal of animal ecology》2009,78(1):253-269