Spacing Patterns in Mobile Animals
01 Nov 1970-Annual Review of Ecology, Evolution, and Systematics (Annual Reviews 4139 El Camino Way, P.O. Box 10139, Palo Alto, CA 94303-0139, USA)-Vol. 1, Iss: 1, pp 239-262
TL;DR: This review will examine concepts of spacing patterns in mobile animals from the perspective of their proximate causes, their ecological consequences, and their adaptive significance.
Abstract: The study of spacing patterns in animals is a field in which ecology and ethology complement each other. Spacing is brought about to a considerable degree by the manner in which different individuals of a species react to each other, and it has important effects on the population dynamics, popula tion genetics, and evolution of species. The dispersion of animals in space and time results, in a proximate sense, from the direct response of individu als to features of the environment and to the presence or absence of other individuals of the species. This review will examine concepts of spacing patterns in mobile animals from the perspective of their proximate causes, their ecological consequences, and their adaptive significance.
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TL;DR: Throughout, emphasis will be placed on strategic aspects of feeding rather than on what Holling (75) has called "tactics," and possible answers to the first problem may be given to the second problem.
Abstract: Natural history is replete with observations on feeding, yet only recently have investigators begun to treat feeding as a device whose performance as measured in net energy yield/feeding time or some other units assumed commensurate with fitness-may be maximized by natural selection (44, 1 13, 135, 156, 181) . The primary task of a theory of feeding strategies is to specify for a given animal that complex of behavior and morphology best suited to gather food energy in a particular environment. The task is one, therefore, of optimization, and like all optimization problems, it may be tri sected: 1. Choosing a currency: What is to be maximized or minimized? 2. Choosing the appropriate cost-benefit functions: What is the mathematical form of the set of expressions with the currency as the dependent variable? 3. Solving for the optimum: What computational technique best finds ex trema of the cost-benefit function? In this review, most of the following section is devoted to possible answers to the first problem. Then four key aspects of feeding strategies will be considered: (a) the optimal diet, (b) the optimal foraging space, (c) the optimal foraging period, and (d) the optimal foraging-group size. For each, possible cost-benefit formulations will be discussed and compared, and predictions derived from these will be matched with data from the literature on feeding. Because the third problem is an aspect of applied mathematics, it will be mostly ignored. Throughout, emphasis will be placed on strategic aspects of feeding rather than on what Holling (75) has called "tactics."
3,356 citations
Cites background from "Spacing Patterns in Mobile Animals"
...This can be reduced by the feeder at a cost, that of territorial defense, and the economics of defendability have been reviewed by Brown (25) and Brown & Orians (26)....
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TL;DR: For several years the study of social behavior has been undergoing a revolution with far-reaching consequences for the social and biological sciences, partly due to growing acceptance of the evidence that the potency of natural selection is overwhelmingly concentrated at levels no higher than that of the individual.
Abstract: For several years the study of social behavior has been undergoing a revolution with far-reaching consequences for the social and biological sciences. Partly responsible are three recent changes in the attitudes of evolutionary biologists. First was growing acceptance of the evidence that the potency of natural selection is overwhelmingly concentrated at levels no higher than that of the individual. Second was revival of the comparative method, especially as applied to behavior and life histories. Third was spread of the realization that not only are all aspects of structure and function of organisms to be understood solely as products of selection, but because of their peculiarly direct relationship to the forces of selection, behavior and life history phenomena, long neglected by the evolutionists, may be among the most predictable of all phenotypic attributes. These ideas have been appreciated by a few biologists for a long time, but they have only recently begun to characterize the science as a whole. Darwin’s discussion of sterility between species as an incidental effect of evolutionary adaptation (41, p. 260) and his refusal to deal with sex ratio selection (42, p. 399) suggest awareness of the difficult problem of determining the levels at which selection is most powerful. Yet significant clarification of this basic issue did not really commence until publication of Wynne-Edwards’ massive volume (179) championing group selection and inadvertently exposing its unlikelihood. As late as 1958, Fisher felt constrained to add to the revised edition of his 1929 classic, The Genetical Theory of Natural Selection, the admonishment (53, p. 49) that his fundamental theorem and its associated considerations, already misused then by decades of population geneticists dealing (as they saw it) with the fitness of populations, refer strictly to "the progressive modification of structure or function only in so far as variations in these are ofadvantage to the individual... [and afford] no corresponding explanation for any properties of animals and plants.., supposed to be of service to the species to which they belong." Williams’ critique (171) provided a significant turning point. Nevertheless, one has only to pick up any biological journal or attend any biological meeting to realize that this question has not yet been settled for all
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TL;DR: An environmental patchwork which exerts powerful influences on the distri butions of organisms, their interactions, and their adaptations is considered.
Abstract: discon tinuities on many scales in time and space. The patterns of these discontinuities produce an environmental patchwork which exerts powerful influences on the distri butions of organisms, their interactions, and their adaptations. Consideration of this environmental patch structure is critical to both the theory and management of populations. Despite the obvious heterogeneity of natural sys te.ms, most of the models that form the theoretical fabric of population biology and ecology (and that are increasingly conditioning our perception of reality) tell mathe matical stories of populations
1,019 citations
TL;DR: The ethnographic record of foragers provides the only direct observations of human behavior in the absence of agriculture, and as such is invaluable for testing hypotheses about human behavioral evolution.
Abstract: Although few hunter-gatherers or foragers exist today, they are well documented in the ethnographic record. Anthropologists have been eager to study them since they assumed foragers represented a lifestyle that existed everywhere before 10,000 years ago and characterized our ancestors into some ill-defined but remote past. In the past few decades, that assumption has been challenged on several grounds. Ethnographically described foragers may be a biased sample that only continued to exist because they occupied marginal habitats less coveted by agricultural people.3 In addition, many foragers have been greatly influenced by their association with more powerful agricultural societies.4 It has even been suggested that Holocene foragers represent a new niche that appeared only with the climatic changes and faunal depletion at the end of the last major glaciation.5 Despite these issues, the ethnographic record of foragers provides the only direct observations of human behavior in the absence of agriculture, and as such is invaluable for testing hypotheses about human behavioral evolution.6.
674 citations
TL;DR: Depression phenomena are familiar to most field ecologists but are seldom incorporated into formal ecological theory, so here the possibility of enhancement of availability, as well as competition, is concerned.
Abstract: A common but not universal consequence of the foraging activities of a predator is a lowering of capture rates with prey in its immediate vicinity. This may result from a number of different processes and need not require actual harvesting of any prey items by the predator. We term this phenomenon "depression" and its ecological consequences are the focus of this paper. A great deal of attention has been devoted to implications of changes in prey abundances as a result of the activity of predators. We will focus on changes in prey availability strictly in terms of the perspective of actual or potential predators. Potential here refers to predators who may visit the site shortly after "the prey have been depressed." Depression phenomena are familiar to most field ecologists but are seldom incorporated into formal ecological theory. While they are not really separate, it will be useful to divide our discussion into several sections, each focusing on a different question. (1) What are the processes by which prey might be depressed? (2) What are the characteristics of prey which affect their depressibility? Their recovery from the depression? (3) Are there prey that cannot be depressed? (4) What are the implications of depression from the viewpoint of a single predator individual? (5) Since prey depressed for one kind of predator are not necessarily depressed for another kind, what are the implications for competition theory? Here we are concerned with the possibility of enhancement of availability, as well as competition.
665 citations
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TL;DR: In this article, the Dickcissel sex ratio is employed as an indirect index of suitability and a sex ratio index was found to be correlated positively with density, consistent with the hypothesis that territorial behavior in males of this species limits their density.
Abstract: This example is provided so that non-theorists may see actual applications of the theory previously described. The Dickcissel sex ratio is employed as an indirect index of suitability. A sex ratio index was found to be correlated positively with density. This is consistent with the hypothesis that territorial behavior in the males of this species limits their density. This study provides a valid example of how the problem can be approached and offers a first step in the eventual identification of the role of territorial behavior in the habitat distribution of a common species.
4,210 citations
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