Food webs, trophic cascades and community structure

Polis, Gary A.

doi:10.1111/j.1442-9993.1994.tb00475.x

Cited by 229 publications

(96 citation statements)

References 122 publications

(233 reference statements)

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“…O papel que plantas e inimigos naturais desempenham na regulação das populações de herbívoros tem sido tema de diversas pesquisas (Power 1992, Hunter et al 1997, Kindlmann & Dixon 2001, Nachman & Zemek 2003. Algumas pesquisas consideram os inimigos naturais como determinantes da abundância de herbívoros nas plantas (efeito "top-down") (Polis 1994, Pace et al 1999, Persson 1999. Essa abordagem tomou forte impulso com a teoria proposta por Hairston et al (1960) de que "o mundo é verde" porque os inimigos naturais regulam as populações de herbívoros a baixas densidades.…”

Section: Do Capsicum Spp Trichomes Infl Uence the Biological Aspectsunclassified

Os tricomas de Capsicum spp. interferem nos aspectos biológicos do ácaro-branco, Polyphagotarsonemus latus Banks (Acari: Tarsonemidae)?

Matos¹,

Pallini²,

Venzon

et al. 2009

Neotrop. entomol.

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-Plant morphology traits can affect the feeding preference, oviposition choice and the vulnerability of herbivores to natural enemies. At long term, these plant variations may infl uence herbivore population dynamics due to the interference on their development, survival and reproduction. In this paper, the development of the broad mite Polyphagotarsonemus latus (Banks) was evaluated on fi ve species of Capsicum with different density of trichomes. We tested the hypothesis that P. latus population growth has a negative relationship with the increase trichome density on leaves. It was assessed a decrease in the intrinsic growth rate (r m ) of P. latus with the increase of trichome density on the leaves tested. The lower r m was measured in leaves of C. praetermissum (r m = 0.46), which has the highest trichome density among the assessed Capsicum species. The highest values of r m were observed on Capsicum species with intermediate densities of trichomes on leaves such as Capsicum frutescens (r m = 0.77) and Capsicum chinense (r m = 0.76). Capsicum spp. trichomes acted as a limiting plant trait for the development of P. latus when they were in higher densities and better distributed on the leaf surface. We also discuss the role of morphologic and chemical plant defenses on P. latus development.KEY WORDS: Pepper, leaf trichome, phytophagous mite, constitutive defense, intrinsic growth rate RESUMO -Variações nas características morfológicas das plantas podem ter efeito imediato sobre a preferência alimentar, escolha de sítios de oviposição e vulnerabilidade de herbívoros a inimigos naturais. A longo prazo, podem ter consequências sobre a dinâmica populacional desses organismos, já que atuam sobre seu desenvolvimento, sobrevivência e reprodução. Neste trabalho, avaliou-se o desenvolvimento de Polyphagotarsonemus latus (Banks) em cinco espécies de Capsicum com diferentes densidades de tricomas. Testou-se a hipótese de que o crescimento populacional de P. latus nessas plantas apresenta relação negativa com o aumento da densidade de tricomas nas folhas. Observou-se um padrão decrescente na taxa intrínseca de crescimento (r m ) de P. latus com o aumento da densidade de tricomas nas folhas. O menor r m foi obtido em folhas de C. praetermissum (r m = 0,46), que apresenta a maior densidade de tricomas entre as espécies de Capsicum avaliadas. Os maiores valores de r m foram observados em espécies de Capsicum com densidade intermediária de tricomas nas folhas, Capsicum frutescens (r m = 0,77) e Capsicum chinense (r m = 0,76). Os tricomas de Capsicum spp. atuaram como fator limitante ao desenvolvimento de P. latus à medida que se apresentaram em maiores densidades e mais bem distribuídos na superfície foliar. Foi discutido ainda o papel da defesa morfológica e química de plantas de Capsicum sobre o desenvolvimento de P. latus.

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Section: Do Capsicum Spp Trichomes Infl Uence the Biological Aspectsunclassified

Os tricomas de Capsicum spp. interferem nos aspectos biológicos do ácaro-branco, Polyphagotarsonemus latus Banks (Acari: Tarsonemidae)?

Matos¹,

Pallini²,

Venzon

et al. 2009

Neotrop. entomol.

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“…Thus, the effects of a predator j on its prey i and vice versa (the latter are partial derivatives of predator j's growth equation with respect to the size of species i) are related to each other (Pimm 1982) according to α ji ¼ e i j c i j X Assuming that the equilibrium biomass densities X i * and feeding rates f j (X i )* and the biomass conversion efficiency values e ij can be directly obtained from observation, such observational values give us the off-diagonal elements of community matrix Α: …”

Section: Linear Functional Responsementioning

confidence: 99%

“…(1) becomes a Lotka-Volterra type equation with intraspecific competition terms (see for example Pimm 1982):…”

Section: Linear Functional Responsementioning

confidence: 99%

Linking saturation, stability and sustainability in food webs with observed equilibrium structure

Neutel

Thorne

2015

Theor Ecol

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Stability of a dynamic equilibrium in a predatorprey system depends both on the type of functional response and on the point of equilibrium on the response curve. Saturation effects from Holling type II responses are known to destabilise prey populations, while a type III (sigmoid) response curve has been shown to provide stability at lower levels of saturation. These effects have also been shown in multi-trophic model systems. However, stability analyses of observed equilibria in real complex ecosystems have as yet not assumed non-linear functional responses. Here, we evaluate the implications of saturation in observed balanced material-flow structures, for system stability and sustainability. We first make the effects of the non-linear functional responses on the interaction strengths in a food web transparent by expressing the elements of Jacobian 'community' matrices for type II and III systems as simple functions of their linear (type I) counterparts. We then determine the stability of the systems and distinguish two critical saturation levels: (1) a level where the system is just as stable as a type I system and (2) a level above which the system cannot be stable unless it is subsidised, separating a stable materially sustainable regime from an unsustainable one. We explain the stabilising and destabilising effects in terms of the feedbacks in the systems. The results shed light on the robustness of observed patterns of interaction strengths in complex food webs and suggest the implausibility of saturation playing a significant role in the equilibrium dynamics of sustainable ecosystems.

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“…Early analyses of collections of the reported food webs from various habitats suggested that food webs show consistent structural patterns (Briand and Cohen 1984, Cohen et al 1990, Pimm et al 1991. However, these patterns were widely debated among the later researchers (Polis 1994, Dunne 2005. The main debates were focused on limitations of data employed for these analyses, such as the poor quality of many food web data, the small subsets of trophic species analyzed, differences in the methodologies used, the definition of a linkage by ignoring the linkage strength, the level and standardization of taxonomic resolution, and mathematical artifacts (Lawton 1989, Winemiller 1990, Hall and Raffaelli 1 991, Martinez 1991, Closs et al 1993, Thompson and Townsend 2000.…”

Section: Introductionmentioning

confidence: 99%

Food Web Structure of Benthic Macrolnvertebrates in a Second Order Stream of the Hanjiang River Basin in Middle China

Huang

Yan

2008

Journal of Freshwater Ecology

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Food webs, trophic cascades and community structure

Cited by 229 publications

References 122 publications

Os tricomas de Capsicum spp. interferem nos aspectos biológicos do ácaro-branco, Polyphagotarsonemus latus Banks (Acari: Tarsonemidae)?

Os tricomas de Capsicum spp. interferem nos aspectos biológicos do ácaro-branco, Polyphagotarsonemus latus Banks (Acari: Tarsonemidae)?

Linking saturation, stability and sustainability in food webs with observed equilibrium structure

Food Web Structure of Benthic Macrolnvertebrates in a Second Order Stream of the Hanjiang River Basin in Middle China

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