Hidden treatments in ecological experiments: re-evaluating the ecosystem function of biodiversity

Oecologia, Journal Year: 1997, Volume and Issue: 110(4), P. 449 - 460

Published: May 21, 1997

Language: Английский

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Constraints and Tradeoffs: Toward a Predictive Theory of Competition and Succession

Oikos, Journal Year: 1990, Volume and Issue: 58(1), P. 3 - 3

Published: May 1, 1990

The development of mechanistic, predictive ecological theory will entail the explicit inclusion organismal tradeoffs, environmental constraints, and basic mechanisms interspecific interaction. This approach was used to address causes species dominance successional dynamics in sandplain vegetation Minnesota. A series field experiments performed over last eight years have shown that major constraints on plants were soil nitrogen disturbance, with competition being a force. Nutrients other than (P, K, Ca, Mg, S trace metals), herbivory, light minor importance. As predicted by theory, superior competitors that, when growing long-term monocultures field, lowered extractable N most. These had high root biomass low tissue levels. Seven alternative hypotheses succession, each named after its underlying tradeoff, proposed tested. colonization - nutrient hypothesis provided best explanation for initial (years 0 40) herbs, whereas versus explained woody plants. Hypotheses involving transient caused differences maximal growth rates rejected. In total, results demonstrate simple interactions, allocationbased can allow models predict composition vegetation.

Language: Английский

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Behavioural ecology: Ecological consequences of adaptive behaviour

Trends in Ecology & Evolution, Journal Year: 1986, Volume and Issue: 1(2), P. 52 - 53

Published: Aug. 1, 1986

Language: Английский

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Simple Rules for Interspecific Dominance in Systems with Exploitative and Apparent Competition

The American Naturalist, Journal Year: 1994, Volume and Issue: 144(5), P. 741 - 771

Published: Nov. 1, 1994

Because mechanistic models of interspecific interactions are often complex, one should deliberately seek simple unifying principles that transcend system-specific details. Earlier work on resource competition has led to the "R* rule," which states a dominant competitor suppresses resources lower level than any other competing species. This rule describes outcome even ornate competition. Here we show analogous rules can characterize systems with predation. We first demonstrate, for two-prey, one-predator model without but predator numerical response leading apparent competition, winning prey supports (and withstands) higher density; is, is described by "P* rule." then develop general in predation inflicted evenhandedly two species single and R* P* hold: both depresses lowest sustains density. next examine more complex differential Assuming closed system (i.e., fixed nutrient pool), portray four-dimensional dynamics two-dimensional graphical model, assess domain applicability dominance systems. address generality our conclusions end examining implications different, reasonable biological constraints community structure.

Language: Английский

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Tigers and their prey: Predicting carnivore densities from prey abundance

Proceedings of the National Academy of Sciences, Journal Year: 2004, Volume and Issue: 101(14), P. 4854 - 4858

Published: March 23, 2004

The goal of ecology is to understand interactions that determine the distribution and abundance organisms. In principle, ecologists should be able identify a small number limiting resources for species interest, estimate densities these at different locations across landscape, then use estimates predict density focal locations. practice, however, development functional relationships between abundances their has proven extremely difficult, examples such predictive ability are very rare. Ecological studies prey requirements tigers Panthera tigris led us develop simple mechanistic model predicting tiger as function density. We tested our using data from landscape-scale long-term (1995–2003) field study estimated in 11 ecologically diverse sites India. used techniques analytical methods specifically addressed sampling detectability, two issues frequently present problems macroecological animal populations. Estimated ungulate ranged 5.3 63.8 animals per km 2 . (3.2–16.8 100 ) were reasonably consistent with predictions. results provide evidence relationship large carnivores under wide range ecological conditions. addition generating important insights into carnivore conservation, provides potentially useful rigorous conduct science.

Language: Английский

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The Role of Abiotic Factors in Community Organization

The American Naturalist, Journal Year: 1991, Volume and Issue: 138(5), P. 1067 - 1091

Published: Nov. 1, 1991

Very few ecological studies have attempted to fully test the integrative role of abiotic and biotic factors in interspecific interactions. There is little if any dispute about value such an approach community ecology. However, there great disagreement over present direction field; we advocate a reemphasis factors. By using literature examples data on salinity reversing competitive relations between fish genus Lucania, suggested these This represents blend traditional fields ecology, physiology, toxicology could facilitate progress As it also be significant part new sought for field physiological Finally, are not arguing that parameters necessarily more important than group multiple may involved regulating structure, only they must included as possible controlling variables complete study.

Language: Английский

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Components of Resource Competition in Plant Communities

Elsevier eBooks, Journal Year: 1990, Volume and Issue: unknown, P. 27 - 49

Published: Jan. 1, 1990

Language: Английский

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COMPETITIVE MECHANISMS UNDERLYING THE DISPLACEMENT OF NATIVE ANTS BY THE INVASIVE ARGENTINE ANT

Ecology, Journal Year: 1999, Volume and Issue: 80(1), P. 238 - 251

Published: Jan. 1, 1999

The Argentine ant (Linepithema humile) is a widespread invasive species that competitively displaces native ants throughout its introduced range. Although this pattern of displacement well known, underlying mechanisms remain little studied. To gain more detailed understanding competitive displacement, I compared the exploitative and interference abilities with those seven it in riparian woodlands northern California. performed four different manipulative field experiments; each measured aspects ability eight study. main goals study were to identify responsible for ant's strong ability, determine if are subject species-specific trade-offs typically present among coexisting ants, so, assess whether trade-off as well. located recruited baits quickly or than did ants—both areas where occurred together (i.e., at edge invasion fronts) they separately away from fronts). Along fronts, also controlled greater proportion ants. In one-on-one interactions, individual workers experienced mixed success overcoming species. When fighting against used both physical aggression chemical defensive compounds, although latter mechanism was often successful deterring opponents. Chemical compounds produced by repellent but appeared no so not able overcome consistently, colonies succeeded displacing most baits. discrepancy between worker-level colony-level suggests numerical advantages key proficiency competition. Like other communities, which negatively correlated. contrast, proficient competition relative displaced thus removed trade-off. These findings imply secure majority available food resources comes into contact may be break constraining because their unique colony structure have escaped natural enemies. observation uncoupled provide general explanation patterns dominance within communities

Language: Английский

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Idealization and the Aims of Science

Published: Jan. 1, 2017

Idealizations are rampant and unchecked in science. That is, they exist throughout our best representations, there is little focus on eliminating them or controlling their influence. This because idealizations, despite falsity, play a positive representational role. account of idealization motivates reconstrual the aims Science has variety epistemic non-epistemic aims, ultimate aim understanding, which can be furthered by sacrificing truth. The deemphasis scientific truth drives wedge between results any metaphysical implications regarding ontology, causation, levels organization.

Language: Английский

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EMPIRICAL APPROACHES TO QUANTIFYING INTERACTION INTENSITY: COMPETITION AND FACILITATION ALONG PRODUCTIVITY GRADIENTS

Ecology, Journal Year: 1999, Volume and Issue: 80(4), P. 1118 - 1131

Published: June 1, 1999

Quantitative synthesis across studies requires consistent measures of effect size among studies. In community ecology, these will often be some measure the strength interactions between taxa. However, indices interaction vary greatly both theoretical and empirical studies, connection hypotheses about metrics that are used to test not explicit. We describe criteria for choosing appropriate methods comparing them at three stages designing a meta-analysis variation in intensity: (1) choice response variable; (2) how is calculated using two treatments; (3) whether there quantitative all taxa systems studied or only qualitatively similar effects within each taxon–system combination. The consequences different choices illustrated with examine relationship competition/facilitation intensity productivity plants. analysis database 296 cases 14 results were unexpected largely inconsistent existing theory: competition significantly declined (rather than increased) productivity, facilitation was sometimes restricted more productive less productive) sites. considerable pattern variables size. For example, on average, competitive final biomass survival decreased standing crop, but growth rate did not. On other hand, facilitative common low crop rate, high survival. Results likely significant log ratio (ln[removal/control]) as relative ([removal − control]/removal), although trends conceptually differ. When grouped single meta-regression similarity showed clearest negative relationship. when same regressions done unique combination taxon site study qualitative slopes averaged over tended from zero These subject number caveats because limitations available data—most notably, extension individual population distribution abundance structure highly problematic. Nevertheless, fact none meta-analyses demonstrated positive we frequently found relationships an important has been apparent surveys it demonstrates potential power ecology. conclude recommendations overcome currently data meta-analytical procedures.

Language: Английский

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