Pathogen-induced reversal of native dominance in a grassland community

Borer, Elizabeth T.; Hosseini, Parviez R.; Seabloom, Eric W.; Dobson, Andrew

doi:10.1073/pnas.0608573104

Cited by 183 publications

(217 citation statements)

References 35 publications

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“…In our system, these trade-offs are expected to explain why exotic annuals have invaded and now dominate California grasslands that were historically dominated by native perennials (Borer et al 2007). Results presented here, in combination with previous work showing that native perennials are both slow returns and more resistant to both BYDV-PAV and its chief aphid vector (Cronin et al 2010b), suggest that slow returns are better defended than quick returns.…”

Section: Discussionsupporting

confidence: 64%

“…This metric is directly relevant to dynamic ecological epidemiology models: it is the multiplier used to adjust the infected host's fitness relative to the uninfected host's fitness (e.g., Roy and Kirchner 2000;Borer et al 2007), where A1). In our approach, resistance and tolerance are measured by the indirect effects of HDT on Dfitness, which can be calculated using standard path multiplication rules (Grace 2006).…”

Section: Integrating Theory and Data: Development Of The Causal Modelmentioning

confidence: 99%

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Why Is Living Fast Dangerous? Disentangling the Roles of Resistance and Tolerance of Disease

Cronin

Rúa

Mitchell

2014

The American Naturalist

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Online enhancement: appendixes. Dryad data: http://dx.doi.org/10.5061/dryad.8mq2q.abstract: Primary axes of host developmental tempo (HDT; e.g., slow-quick return continuum) represent latent biological processes and are increasingly used to a priori identify hosts that contribute disproportionately more to pathogen transmission. The influence of HDT on host contributions to transmission depends on how HDT influences both resistance and tolerance of disease. Here, we use structural equation modeling to address known limitations of conventional measures of resistance and tolerance. We first provide a general resistance-tolerance metamodel from which system-specific models can be derived. We then develop a model specific to a group of vector-transmitted viruses that infect hundreds of grass species worldwide. We tested the model using experimental inoculations of six phylogenetically paired grass species. We found that (1) host traits covaried according to a prominent HDT axis, the slow-quick continuum; (2) infection caused a greater reduction in the performance of quick returns, with 180% of that greater impact explained by lesser resistance; (3) resistance-tolerance trade-off did not occur; and (4) phylogenetic control was necessary to measure the slow-quick continuum, resistance, and tolerance. These results support the conclusion that HDT's main influence on host contributions to transmission is via resistance. More broadly, this study provides a framework for quantifying HDT's influence on host contributions to transmission.

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Section: Discussionsupporting

confidence: 64%

Section: Integrating Theory and Data: Development Of The Causal Modelmentioning

confidence: 99%

Why Is Living Fast Dangerous? Disentangling the Roles of Resistance and Tolerance of Disease

Cronin

Rúa

Mitchell

2014

The American Naturalist

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“…Empirical work over the last several decades has shown that multiple factors regulate the outcome of plant species interactions, causing different plant species to compete for different resources (16,17) and limit one another via shared pathogens and consumers (18). With such a diversity of mechanisms controlling the interaction between competitors, a simple transitive hierarchy is highly unlikely.…”

Section: Modelmentioning

confidence: 99%

A competitive network theory of species diversity

Allesina

Levine²

2011

Proc. Natl. Acad. Sci. U.S.A.

331

386

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Nonhierarchical competition between species has been proposed as a potential mechanism for biodiversity maintenance, but theoretical and empirical research has thus far concentrated on systems composed of relatively few species. Here we develop a theory of biodiversity based on a network representation of competition for systems with large numbers of competitors. All species pairs are connected by an arrow from the inferior to the superior. Using game theory, we show how the equilibrium density of all species can be derived from the structure of the network. We show that when species are limited by multiple factors, the coexistence of a large number of species is the most probable outcome and that habitat heterogeneity interacts with network structure to favor diversity.competitive exclusion | rock-paper-scissor | neutral theory | niche theory E cologists have long sought to explain how a wide diversity of species coexists in nature (1). Coexistence is a conundrum because if two species share the same niche, the competitive exclusion principle predicts the extinction of the inferior competitor (2). This foundational principle continues to motivate advances in niche and neutral theories (3-5) of coexistence, which use niche differences and species equivalence, respectively, to avoid competitive exclusion. However, each theory suffers shortcomings. Field evidence that classic resource-based niche differences are essential for coexistence is rare (6-8), whereas the species equivalence assumption of neutral theory is hard to reconcile with nature. These shortcomings justify the quantitative exploration of less conventional niche mechanisms of coexistence.Here, we ask how embedding pairs of superior and inferior species in a network of competitors alters the outcome of competition and influences patterns of relative abundance. We find that although the competitive exclusion principle certainly holds for any pair of competitors, when multiple factors determine the outcome of competition and species are embedded in competitive networks, a large number of species can coexist. The coexistence relies on the stabilizing effect of intransitivities (9-12) that emerge in these networks rather than more traditional pairwise niche differences. By combining a game theoretical framework with graph theory and dynamical systems (13, 14), we show how the equilibrium abundance of all species can be determined from the competitive network, how species diversity relates to the number of limiting factors, and how spatial heterogeneity combines with intransitivity to interactively favor diversity maintenance. ModelThe pairwise competitive relationships between species in a community can be expressed as a network, or more formally, a tournament, in which species are the nodes and arrows connect the competitive inferior to the superior competitor (Fig. 1A). In the simplest case, where all species in a system compete for a single limiting resource, their competitive abilities should be transitive: Species A beats all others, B beats all but...

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“…where κ is the carrying capacity, b i is the rate of recruitment of species i, and all trees are assumed to exhibit equivalent competitive effects irrespective of species or disease status (Holt and Pickering, 1985;Preedy et al, 2007;Borer et al, 2007). However, the results of the optimization problem remain unchanged for the use of more complex growth functions such a logistic function.…”

Section: The Modelmentioning

confidence: 99%

Optimization of control strategies for epidemics in heterogeneous populations with symmetric and asymmetric transmission

Ndeffo-Mbah¹,

Gilligan²

2010

Journal of Theoretical Biology

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There is growing interest in incorporating economic factors into epidemiological models in order to identify optimal strategies for disease control when resources are limited. In this paper we consider how to optimize the control of a pathogen that is capable of infecting multiple hosts with different rates of transmission within and between species. Our objective is to find control strategies that maximize the discounted number of healthy individuals. We consider two classes of host-pathogen system, comprising two host species and a common pathogen, one with asymmetrical and the other with symmetrical transmission rates, applicable to a wide range of SI (susceptible-infected) epidemics of plant and animal pathogens. We motivate the analyses with an example of sudden oak death in California coastal forests, caused by Phytophthora ramorum, in communities dominated by bay laurel (Umbellularia californica) and tanoak (Lithocarpus densiflorus). We show for the asymmetric case that it is optimal to give priority in treating disease to the more infectious species, and to treat the other species only when there are resources left over. For the symmetric case, we show that although a switching strategy is an optimum, in which preference is first given to the species with the lower level of susceptibles and then to the species with the higher level of susceptibles, a simpler strategy that favours treatment of infected hosts for the more susceptible species is a robust alternative for practical application when the optimal switching time is unknown. Finally, since transmission rates are notoriously difficult to estimate, we analyze the robustness of the strategies when the true state with respect to symmetry or otherwise is unknown but one or other is assumed.

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Pathogen-induced reversal of native dominance in a grassland community

Cited by 183 publications

References 35 publications

Why Is Living Fast Dangerous? Disentangling the Roles of Resistance and Tolerance of Disease

Why Is Living Fast Dangerous? Disentangling the Roles of Resistance and Tolerance of Disease

A competitive network theory of species diversity

Optimization of control strategies for epidemics in heterogeneous populations with symmetric and asymmetric transmission

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