How different would a world without herbivory be?: A search for generality in ecology

Bigger, David; Marvier, Michelle

doi:10.1002/(sici)1520-6602(1998)1:2<60::aid-inbi4>3.0.co;2-z

Cited by 83 publications

(87 citation statements)

References 8 publications

(16 reference statements)

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“…Meta-analysis (Gurevitch and Hedges 2001) provides a useful tool for extracting general results from a suite of individual studies. Previous meta-analyses have gauged the negative effects of competitors (Gurevitch et al 1992, Goldberg et al 1999, Maestre et al 2005, herbivores (Bigger and Marvier 1998, Hawkes and Sullivan 2001, Yeo 2005, pathogens (Rosenberg et al 2004), and nectar robbers (Irwin et al 2001). In contrast, meta-analyses evaluating interactions that positively affect individual plant performance have focused only on mycorrhizal mutualisms (Borowicz 2001) and plant-plant facilitation (Goldberg et al 1999, Gomez-Aparicio et al 2004, Maestre et al 2005 [also see Lortie andCallaway 2006 andMaestre et al 2006]).…”

Section: Introductionmentioning

confidence: 99%

Direct and Interactive Effects of Enemies and Mutualists on Plant Performance: A Meta-Analysis

Morris

Hufbauer

Agrawal

et al. 2007

Ecology

222

221

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Abstract. Plants engage in multiple, simultaneous interactions with other species; some (enemies) reduce and others (mutualists) enhance plant performance. Moreover, effects of different species may not be independent of one another; for example, enemies may compete, reducing their negative impact on a plant. The magnitudes of positive and negative effects, as well as the frequency of interactive effects and whether they tend to enhance or depress plant performance, have never been comprehensively assessed across the many published studies on plant-enemy and plant-mutualist interactions. We performed a meta-analysis of experiments in which two enemies, two mutualists, or an enemy and a mutualist were manipulated factorially. Specifically, we performed a factorial meta-analysis using the log response ratio. We found that the magnitude of (negative) enemy effects was greater than that of (positive) mutualist effects in isolation, but in the presence of other species, the two effects were of comparable magnitude. Hence studies evaluating single-species effects of mutualists may underestimate the true effects found in natural settings, where multiple interactions are the norm and indirect effects are possible. Enemies did not on average influence the effects on plant performance of other enemies, nor did mutualists influence the effects of mutualists. However, these averages mask significant and large, but positive or negative, interactions in individual studies. In contrast, mutualists ameliorated the negative effects of enemies in a manner that benefited plants; this overall effect was driven by interactions between pathogens and belowground mutualists (bacteria and mycorrhizal fungi). The high frequency of significant interactive effects suggests a widespread potential for diffuse rather than pairwise coevolutionary interactions between plants and their enemies and mutualists. Pollinators and mycorrhizal fungi enhanced plant performance more than did bacterial mutualists. In the greenhouse (but not the field), pathogens reduced plant performance more than did herbivores, pathogens were more damaging to herbaceous than to woody plants, and herbivores were more damaging to crop than to non-crop plants (suggesting evolutionary change in plants or herbivores following crop domestication). We discuss how observed differences in effect size might be confounded with methodological differences among studies.

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Section: Introductionmentioning

confidence: 99%

Direct and Interactive Effects of Enemies and Mutualists on Plant Performance: A Meta-Analysis

Morris

Hufbauer

Agrawal

et al. 2007

Ecology

222

221

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“…Given the ubiquity of plantconsumer interactions, predicting their outcomes and identifying conditions that mediate these outcomes are important conceptual challenges, as well as practical issues in the contexts of plant conservation (e.g., Bevill et al 1999, Stiling et al 2004) and biological control of weeds (e.g., McEvoy et al 1993, Shea andKelly 1998). The extent to which consumers influence the abundance, dynamics, and distribution of their host plant populations has been a topic of persistent debate (Hairston et al 1960, Ehrlich and Birch 1967, Harper 1977, Strong et al 1984, Louda 1989a, Crawley 1990, Louda et al 1990, Bigger and Marvier 1998, Strauss and Zangerl 2002, Halpern and Underwood 2006, Maron and Crone 2006. On the one hand, there is a vast literature, from both natural and managed systems, documenting the injurious effects of herbivory on the vegetative performance and reproductive success of individual plants (reviewed in Crawley 1989Crawley , 1997.…”

Section: Introductionmentioning

confidence: 99%

Impacts of insect herbivory on cactus population dynamics: experimental demography across an environmental gradient

Miller

Louda

Rose

et al. 2009

Ecological Monographs

110

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Miller, Tom E. X.; Louda, Svata M.; Rose, Karen A.; and Eckberg, James O., "Impacts of insect herbivory on cactus population dynamics: experimental demography across an environmental gradient" (2009 Abstract. Understanding the role of consumers in plant population dynamics is important, both conceptually and practically. Yet, while the negative effects of herbivory on plant performance have been well documented, we know much less about how individuallevel damage translates to impacts on population growth or whether spatial variation in herbivory affects patterns of plant distribution. We studied the role of insect herbivory in the dynamics and distribution of the tree cholla cactus (Opuntia imbricata), a long-lived perennial plant, across an elevational gradient in central New Mexico, USA, from low-elevation grassland (1670 m) to a grassland-mountain transition zone (1720 m) to the rocky slopes of the Los Pinos Mountains (1790 m). Tree cholla density increased significantly with elevation, while abundance of and damage by a suite of native, cactus-feeding insects decreased. We combined field experiments and demographic models to test the hypothesis that systematic spatial variation in chronic insect herbivory limits the tree cholla distribution to a subset of suitable habitat across the gradient. Our results support this hypothesis.We found that key demographic functions (survival, growth, fecundity) and the responses of these functions to experimental reductions in insect herbivory varied across the gradient. The effects of insect exclusion on plant growth and seed production were strongest in the lowelevation grassland and decreased in magnitude with increasing elevation. We used the experimental data to parameterize integral projection models (IPM), which predict the asymptotic rate of population increase (k). The modeling results showed that insect herbivory depressed k and that the magnitude of this effect was context-dependent. The effect of insect herbivory on population growth was strongest at low elevation (Dk low ¼ 0.095), intermediate at mid elevation (Dk mid ¼ 0.046), and weakest at high elevation (Dk high ¼ À0.0089). The total effect of insects on k was due to a combination of reductions in growth and in fecundity and their combination; the relative contribution of each of these effects varied spatially. Our results, generated by experimental demography across a heterogeneous landscape, provide new insights into the role of native consumers in the population dynamics and distribution of abundance of long-lived native plants.

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“…Preference for the symmetrical view may reflect belief in a balance of nature, or it may represent a logical starting point for theoretical models of ecological and coevolutionary dynamics of herbivore-plant, predator-prey, and parasite-host population interactions. More substantively, a growing number of ecological studies have demonstrated that removing herbivores or pathogens often increases plant population size or plant fitness (Bigger & Marvier, 1998;Marquis, 1992), alters the pattern of selection on genetic variation in chemical and morphological characters that have been shown to reduce herbivore damage on plants in the field (Mauricio & Rausher, 1997), and changes the speed and direction of ecological succession (Bach, 2001;Brown & Gange, 1992;Carson & Root, 1999;Fagan & Bishop, 2000). These findings bolster the assumption that insect herbivores impose strong negative effects on plants and support the symmetrical view that insects and plants exert major effects on each other.…”

Section: Introductionmentioning

confidence: 99%

Insect‐plant interactions on a planet of weeds

McEvoy

2002

Entomologia Exp Applicata

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Two conflicting views confront ecologists and evolutionary biologists on the degree of symmetry in interactions between plants and phytophagous insects. The symmetrical view holds that insects and plants have strong effects on one another's evolutionary and ecological dynamics. Thus, herbivores are regarded as a major influence on plant distribution and abundance in contemporary ecosystems, and coevolution is commonly invoked to explain adaptive radiation in plants and insects, host specialization in insects, as well as much of the morphological and chemical variety observed in plants. The asymmetrical view acknowledges that plants have major effects on insects, but claims that insects seldom impose significant effects on plants. Proponents of the asymmetric view tend to ignore or discount insect-plant interactions in communities and ecosystems altered by human impacts. If we recognize the scope and scale of human impacts, and ways in which these impacts change insect-plant interactions, then our views about symmetry or asymmetry in insect-plant interactions will change. To understand, predict, and manage insect herbivory we need to study it in all its manifestations. In particular, the study of interactions involving alien species is both an urgent priority for environmental management and potentially a source of ecological insights on the role of herbivores in plant population and community dynamics. A complete theory of insect/host plant interactions must explain and predict interactions both within and beyond the native range. Such a theory might guide efforts to deal with environmental problems stemming from rapid rates of extinction and homogenization of the world's biota.

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How different would a world without herbivory be?: A search for generality in ecology

Cited by 83 publications

References 8 publications

Direct and Interactive Effects of Enemies and Mutualists on Plant Performance: A Meta-Analysis

Direct and Interactive Effects of Enemies and Mutualists on Plant Performance: A Meta-Analysis

Impacts of insect herbivory on cactus population dynamics: experimental demography across an environmental gradient

Insect‐plant interactions on a planet of weeds

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