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71.
Species pools,community completeness and invasion: disentangling diversity effects on the establishment of native and alien species 下载免费PDF全文
Jonathan A. Bennett Kersti Riibak Ene Kook Ülle Reier Riin Tamme C. Guillermo Bueno Meelis Pärtel 《Ecology letters》2016,19(12):1496-1505
Invasion should decline with species richness, yet the relationship is inconsistent. Species richness, however, is a product of species pool size and biotic filtering. Invasion may increase with richness if large species pools represent weaker environmental filters. Measuring species pool size and the proportion realised locally (completeness) may clarify diversity‐invasion relationships by separating environmental and biotic effects, especially if species’ life‐history stage and origin are accounted for. To test these relationships, we added seeds and transplants of 15 native and alien species into 29 grasslands. Species pool size and completeness explained more variation in invasion than richness alone. Although results varied between native and alien species, seed establishment and biotic resistance to transplants increased with species pool size, whereas transplant growth and biotic resistance to seeds increased with completeness. Consequently, species pools and completeness represent multiple independent processes affecting invasion; accounting for these processes improves our understanding of invasion. 相似文献
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Invasion-resistance in experimental grassland communities: species richness or species identity? 总被引:10,自引:0,他引:10
The question as to why some communities are more invasible than others has pro-found implications for conservation biology and land management. The theoretical issues involved go right to the heart of our understanding of species coexistence and community assembly. The experiment reported here indicates that for productive, small-scale grassland plots, species identity matters more than species richness in determining both the number of invading species and the total biomass of invasives. 相似文献
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Parasites reproduce and are subject to natural selection at several different, but intertwined, levels. In the recent paper,
Gilchrist and Coombs (Theor. Popul. Biol. 69:145–153, 2006) relate the between-host transmission in the context of an SI model
to the dynamics within a host. They demonstrate that within-host selection may lead to an outcome that differs from the outcome
of selection at the host population level. In this paper we combine the two levels of reproduction by considering the possibility
of superinfection and study the evolution of the pathogen’s within-host reproduction rate p. We introduce a superinfection function φ = φ(p,q), giving the probability with which pathogens with trait q, upon transmission to a host that is already infected by pathogens with trait p, “take over” the host. We consider three cases according to whether the function q → φ(p,q) (i) has a discontinuity, (ii) is continuous, but not differentiable, or (iii) is differentiable in q = p. We find that in case (i) the within-host selection dominates in the sense that the outcome of evolution at the host population
level coincides with the outcome of evolution in a single infected host. In case (iii), it is the transmission to susceptible
hosts that dominates the evolution to the extent that the singular strategies are the same as when the possibility of superinfections
is ignored. In the biologically most relevant case (ii), both forms of reproduction contribute to the value of a singular
trait. We show that when φ is derived from a branching process variant of the submodel for the within-host interaction of
pathogens and target cells, the superinfection functions fall under case (ii). We furthermore demonstrate that the superinfection
model allows for steady coexistence of pathogen traits at the host population level, both on the ecological, as well as on
the evolutionary time scale.
相似文献
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Kathleen S. Knight Jacek Oleksyn rzej M. Jagodzinski Peter B. Reich Marek Kasprowicz 《Diversity & distributions》2008,14(4):666-675
The North American woody species, Prunus serotina Ehrh., is an aggressive invader of forest understories in Europe. To better understand the plant invasion process, we assessed understorey plants and Prunus serotina seedlings that have colonized a 35-year-old replicated common-garden experiment of 14 tree species in south-western Poland. The density and size of established (> 1 year old) P. serotina seedlings varied among overstorey species and were related to variation in light availability and attributes of the understorey layer. In a multiple regression analysis, the density of established P. serotina seedlings was positively correlated with light availability and understorey species richness and negatively correlated with understorey species cover. These results suggest that woody invader success is adversely affected by overstorey shading and understorey competition for resources. Simultaneously, however, invader success may generally be positively associated with understorey species richness because both native and invasive plant colonization respond similarly to environmental conditions, including those influenced by overstorey tree species. Identification of characteristics of forests that increase their susceptibility to invasion may allow managers to target efforts to detect invasives and to restore forests to states that may be less invasible. 相似文献
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Melbourne BA Cornell HV Davies KF Dugaw CJ Elmendorf S Freestone AL Hall RJ Harrison S Hastings A Holland M Holyoak M Lambrinos J Moore K Yokomizo H 《Ecology letters》2007,10(1):77-94
We review and synthesize recent developments in the study of the invasion of communities in heterogeneous environments, considering both the invasibility of the community and impacts to the community. We consider both empirical and theoretical studies. For each of three major kinds of environmental heterogeneity (temporal, spatial and invader-driven), we find evidence that heterogeneity is critical to the invasibility of the community, the rate of spread, and the impacts on the community following invasion. We propose an environmental heterogeneity hypothesis of invasions, whereby heterogeneity both increases invasion success and reduces the impact to native species in the community, because it promotes invasion and coexistence mechanisms that are not possible in homogeneous environments. This hypothesis could help to explain recent findings that diversity is often increased as a result of biological invasions. It could also explain the scale dependence of the diversity–invasibility relationship. Despite the undoubted importance of heterogeneity to the invasion of communities, it has been studied remarkably little and new research is needed that simultaneously considers invasion, environmental heterogeneity and community characteristics. As a young field, there is an unrivalled opportunity for theoreticians and experimenters to work together to build a tractable theory informed by data. 相似文献
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Jane A. Catford Annabel L. Smith Peter D. Wragg Adam T. Clark Margaret Kosmala Jeannine Cavender‐Bares Peter B. Reich David Tilman 《Ecology letters》2019,22(4):593-604
Much uncertainty remains about traits linked with successful invasion – the establishment and spread of non‐resident species into existing communities. Using a 20‐year experiment, where 50 non‐resident (but mostly native) grassland plant species were sown into savannah plots, we ask how traits linked with invasion depend on invasion stage (establishment, spread), indicator of invasion success (occupancy, relative abundance), time, environmental conditions, propagule rain, and traits of invaders and invaded communities. Trait data for 164 taxa showed that invader occupancy was primarily associated with traits of invaders, traits of recipient communities, and invader‐community interactions. Invader abundance was more strongly associated with community traits (e.g. proportion legume) and trait differences between invaders and the most similar resident species. Annuals and invaders with high‐specific leaf area were only successful early in stand development, whereas invaders with conservative carbon capture strategies persisted long‐term. Our results indicate that invasion is context‐dependent and long‐term experiments are required to comprehensively understand invasions. 相似文献
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Aim Predicting and preventing invasions depends on knowledge of the factors that make ecosystems susceptible to invasion. Current studies generally rely on non‐native species richness (NNSR) as the sole measure of ecosystem invasibility; however, species identity is a critical consideration, given that different ecosystems may have environmental characteristics suitable to different species. Our aim was to examine whether non‐native freshwater fish community composition was related to ecosystem characteristics at the landscape scale. Location United States. Methods We described spatial patterns in non‐native freshwater fish communities among watersheds in the Mid‐Atlantic region of the United States based on records of establishment in the U.S. Geological Survey’s Nonindigenous Aquatic Species Database. We described general relationships between non‐native species and ecosystem characteristics using canonical correspondence analysis. We clustered watersheds by non‐native fish community and described differences among clusters using indicator species analysis. We then assessed whether non‐native communities could be predicted from ecosystem characteristics using random forest analysis and predicted non‐native communities for uninvaded watersheds. We estimated which ecosystem characteristics were most important for predicting non‐native communities using conditional inference trees. Results We identified four non‐native fish communities, each with distinct indicator species. Non‐native communities were predicted based on ecosystem characteristics with an accuracy of 80.6%, with temperature as the most important variable. Relatively uninvaded watersheds were predicted to be invasible by the most diverse non‐native community. Main conclusions Non‐native species identity is an important consideration when assessing ecosystem invasibility. NNSR alone is an insufficient measure of invasibility because ecosystems with equal NNSR may not be equally invasible by the same species. Our findings can help improve predictions of future invasions and focus management and policy decisions on particular species in highly invasible ecosystems. 相似文献
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