@article {939,
	title = {Trait-initiated indirect effects due to changes in consumption rates in simple food webs},
	journal = {Ecology},
	volume = {85},
	year = {2004},
	note = {J
APR},
	month = {2004///},
	pages = {1029 - 1038},
	abstract = {This article explores the potential indirect effects due to changes in consumption-related traits of a focal prey species in each of two simple food webs. The systems considered are: one predator exploiting two independent prey, and one predator exploiting two prey that use a common limiting resource. In each system, the indirect effect of a change in a consumption-related parameter of one prey species on the population density of the other prey is determined. When prey only share a predator, the change in one prey{\textquoteright}s density produced by a change in the other prey{\textquoteright}s vulnerability to the predator is determined by whether or not that second prey is initially overexploited; i.e., whether its exploiter{\textquoteright}s intake decreases with an increase in the attack rate. Increases in the vulnerability of an overexploited prey decrease the predator population and thereby indirectly increase the population size of the second prey. Increases in the vulnerability of a prey that is not overexploited have the opposite effects on both the predator and second prey populations. Both of these outcomes can be reversed by strong direct density dependence in the predator, provided the predator exhibits satiation. In the food web with a shared food and a shared resource, increases in predator vulnerability of the more vulnerable prey species always increase the population size of the more resistant prey species. However, increases in the vulnerability of the more resistant prey can either increase or decrease the population size of the more vulnerable prey species. When the more resistant prey becomes better at capturing the resource, the less resistant may either increase or decrease. Overexploitation also explains these outcomes. General principles for understanding the consequences of changes in vulnerabilities or attack rates are discussed},
	keywords = {CONSEQUENCES, DENSITY, DENSITY DEPENDENCE, DENSITY-DEPENDENCE, DEPENDENCE, food web, food webs, FOOD-WEB, indirect effects, POPULATIONS, PREDATOR, PREY, SIZE},
	isbn = {0012-9658},
	url = {ISI:000220766600014},
	author = {Abrams,P.A.}
}
@article {940,
	title = {Defining and measuring the impact of dynamic traits on interspecific interactions},
	journal = {Ecology},
	volume = {88},
	year = {2007},
	note = {J
OCT},
	month = {2007///},
	pages = {2555 - 2562},
	abstract = {Trait- and density-mediated indirect effects describe different pathways by which indirect interactions in food webs are propagated from one species to another, through changes in intermediate species. A series of articles in Ecology has progressively altered the original definitions of "trait-mediated{\textquoteright}{\textquoteright} to the point where understanding is being impeded. The most recent of these articles are two meta-analyses that use "trait-mediated{\textquoteright}{\textquoteright} to describe the demographic costs to a prey species of employing anti-predator defenses. These same articles introduce a companion term, "density-mediated interaction,{\textquoteright}{\textquoteright} apparently to describe direct and indirect interactions that only involve changes in population density due to consumption by predators. This new terminology has many disadvantages, including ( 1) using a general term for a relatively narrow group of processes; ( 2) using "mediated{\textquoteright}{\textquoteright} in a manner inconsistent with existing terminology; ( 3) confusing the accepted definitions of different types of indirect effects; and ( 4) providing a highly incomplete measure of the impact of behavior on the predator - prey interaction. Solutions to these problems and the meaning of the meta-analyses are discussed},
	keywords = {defense, ecology, food webs, indirect effects, indirect interactions, interactions, INTERSPECIFIC INTERACTIONS, PREDATOR, predators, PREY},
	isbn = {0012-9658},
	url = {ISI:000250714200016},
	author = {Abrams,P.A.}
}
@article {942,
	title = {Measuring the impact of dynamic antipredator traits on predator-prey-resource interactions},
	journal = {Ecology},
	volume = {89},
	year = {2008},
	note = {J
JUN},
	month = {2008///},
	pages = {1640 - 1649},
	abstract = {This article analyzes the limitations of the most widely used method for quantifying the impact of dynamic antipredator traits on food chain dynamics and discusses alternative approaches. The standard method for a predator-prey-resource chain estimates the effects of the prey{\textquoteright}s defensive behavior by comparing population densities or fitness measures in a {\textquoteright}{\textquoteright}predator cue{\textquoteright}{\textquoteright} treatment to those in a no-predator treatment. This design has been interpreted as providing a measure of the {\textquoteright}{\textquoteright}nonconsumptive effect{\textquoteright}{\textquoteright} of the predator on the prey and the {\textquoteright}{\textquoteright}trait-mediated indirect effect{\textquoteright}{\textquoteright} of the predator on the resource. Other approaches involve measurements of the impact of the behavior in the presence of functional predators. The questions addressed here are: (1) How consistent are the results of different approaches? (2) How time-dependent are their results? (3) How well do they correspond to theoretical measures of effect size? (4) How useful are the measurements in understanding system dynamics? A model of a tritrophic system in which the prey species adjusts a defensive trait adaptively is used to evaluate the experimental designs. Measures of changes in prey fitness or population density in a cue treatment generally include offsetting effects of the cost of the behavior and the benefit of more resources. This means that the sign of the effect, as well as its magnitude, may change depending on when the experiment is terminated. Because predation is not present in the cue treatment, few conclusions can be drawn about the impact of the behavior on population densities or fitness of the prey in a natural setting with predators. Cue experiments often do not accurately separate trait-mediated from density-mediated effects on the resource. Most scalar measures of effects are sensitive to experimental duration and initial densities. Use of a wider range of experimental designs to measure trait-related effects is called for},
	keywords = {DYNAMICS, interactions, predation, PREDATOR, predators, PREY, SIZE},
	isbn = {0012-9658},
	url = {ISI:000256540300017},
	author = {Abrams,P.A.}
}
