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Journal ArticleDOI

Interspecific Territories of Birds

01 Oct 1964-Ecology (John Wiley & Sons, Ltd)-Vol. 45, Iss: 4, pp 736-745
TL;DR: It is suggested that Darwinian selection at the level of the individual permits an understanding of the known structure of avian communities and that there is no need at present to invoke new selective mechanisms at thelevel of the community or ecosystem.
Abstract: Territories of birds, usually defended against conspecific individuals, are sometimes defended against individuals of other species. Since such behavior is demanding both of time and energy, natural selection should favor ecological should favor ecological divergence, the establishment of overlapping territories, and the reduction of aggression. Lack of divergence in modes of exploitation could mean that insufficient time has elapsed for the changes to be completed or that the environment imposes some limitation preventing the evolution of the required degree of divergence. Such environmental limitation can be predicted in (a) structurally simple environments, (b) when feeding sites are strongly stratified in structurally complex vegetation, or (c) when the presence of other species in the environment prevents divergence in certain directions. The known cases of interspecific territoriality in birds are analyzed and shown to be largely in accordance with these predictions, although several cases of overlapping territories in situations where interspecific territoriality has been predicted provide relationships worthy of further study. We suggest that Darwinian selection at the level of the individual permits an understanding of the known structure of avian communities and that there is no need at present to invoke new selective mechanisms at the level of the community or ecosystem.
Citations
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Journal ArticleDOI
TL;DR: Female yellow-headed blackbirds in eastern Washington State settle to nest at higher densities on marshes with higher emergence rates of odonates, the most important prey delivered to nestlings, but settling densities of females were not correlated with odonate emergence rates on individual territories or onindividual territories plus adjacent ones.
Abstract: Female yellow-headed blackbirds in eastern Washington State settle to nest at higher densities on marshes with higher emergence rates of odonates, the most important prey delivered to nestlings. However, settling densities of females were not correlated with odonate emergence rates on individual territories or on individual territories plus adjacent ones. Apparently, females assessed production of insects on breeding marshes at the time they settled, and they used this information when making settling decisions. However, they selected nest sites on the basis of vegetation density rather than food availability. The complexity of decision making by female yellowheads would not have been detected had our analysis been restricted to one spatial scale. Because interpretations of habitat selection behavior are scale-dependent, careful attention to scale and performing analyses on more than one spatial scale are essential in studies of habitat selection. Habitat selection, an almost universal activity among animals, affects nearly all of an individual's subsequent choices. As a result, considerable attention has been paid to both the theory of habitat selection and the ways in which organisms in different taxa actually evaluate and select from the different options available (Cody 1985). A general guiding theoretical principle is that preferences among environments should coevolve with the qualities of those environments. That is, organisms should respond positively to (prefer) environments in which their sur- vival and reproductive success is good (Levins 1968; Orians 1980a). Individuals that elect to settle in less suitable environments leave fewer surviving offspring than those choosing better habitats. Whereas the logic of this general approach is compelling, correlations between habitat features and success may be low or difficult to assess in real-world situa- tions. A normally good environment may be poor because other factors (diseases, predators) reduce quality below expected levels or because resources are tempo- rarily depressed. Ease of assessment may depend on the grain of environmental patches in relation to the scale of exploitation by the organism (Levins 1968). Moreover, individuals may have difficulty in assessing the actual qualities of environments. This is especially true when the value of the habitat depends on its ability to provide resources for some time into the future. Some of these resources may not be present or evident at the time the decision must be made. In this article, we explore stages in the habitat-selection process and consider different spatial scales of decisions with the objective of providing a more compre- hensive way of viewing details of habitat-selection processes.

822 citations

Journal ArticleDOI
19 Dec 1970-Nature
TL;DR: It seems to be a neglected question whether the harm delivered to an adversary is always merely an unfortunate consequence of adaptations for survival, and whether such harm ever be adaptive in itself.
Abstract: INCIDENTS in which an animal attacks another of the same species, drives it from a territory, or even kills and devours it are commonplace. They may be described as examples of biological selfishness. The effect consists of two obvious parts: the gains (in fitness) of the victor and the losses of the victim. Attempts to secure the gains are easily understood to be adaptive: this is the fundamental response to what Darwin called the “struggle for existence”. But, considering the more controversial catch-phrase of evolutionary theory—“the survival of the fittest”—it seems to be a neglected question whether the harm delivered to an adversary is always merely an unfortunate consequence of adaptations for survival. Could such harm ever be adaptive in itself ? Or nearer, to the possibility of a test, would we ever expect an animal to be ready to harm itself in order to harm another more ? Such behaviour could be called spite. Is it ever observed ?

806 citations

Journal ArticleDOI
TL;DR: Evidence of an adaptive function of sexual dimorphism in size in woodpeckers is presented by relating degrees of morphologicalDimorphism and sexual divergence in foraging behavior in two melanerpine species, the stronglyDimorphic Hispaniolan Woodpecker of Haiti and the Dominican Republic and the moderately dimorphic Golden-fronted Woodpeker of continental North and Central America.
Abstract: Adaptive radiation has been defined as the evolutionary divergence of members of a phyletic line into different niches or adaptive zones (Mayr, 1963:633). Although it has been customary to think of adaptive radiation solely in terms of species or races, a growing body of evidence indicates that some degree of radiation occurs also within populations, as individuals come to occupy different subniches or adaptive subzones, subdividing and, perhaps, expanding the total niche or zone utilized by the population. Probably all species show some degree of ecological variation, either polymorphic or continuous. But this phenomenon is being studied in only a few groups of organisms, notably in Drosophila, in which chromosomal polymorphism has been interpreted as a. means of adaptation of populations to heterogeneous environments (Dobzhansky, * 1961, 1963, 1965). Theoretical bases for research on ecological variation in animal populations have been provided by Ludwig (1950), Levene (1953)) da Cunha and Dobzhansky (1954), Dempster (1955), Li (1955), Carson (1959), and Levins (1962, 1963). In birds, as in other vertebrates, the sexes usually differ in size if not also in proportions of body parts, including those used in feeding (Amadon, 1959) ; and, especially where the degree of sexual dimorphism, which is a form of polymorphism (Ford, 1961: 12), is marked, it seems probable that the morphological divergence has ecological significance in adapting the sexes to different subniches. However, there is only an occasional reference in the literature to sexual dimorphism in relation to niche utilization (e.g., Pitelka, 1950; Rand, 19.52), and, in general, the whole problem of ecological variation in populations has been neglected by vertebrate ecologists. The primary purpose of this report is to present evidence of an adaptive function of sexual dimorphism in size in woodpeckers by relating degrees of morphological dimorphism and sexual divergence in foraging behavior in two melanerpine species, the strongly dimorphic Hispaniolan Woodpecker (Centurus striatus) of Haiti and the Dominican Republic and the moderately dimorphic Golden-fronted Woodpecker (Ce&zmus awifrons) of continental North and Central America. In addition, the paper surveys other evidence that sexual dimorphism in birds is related to differential niche utilization. Finally, some evolutionary aspects of sexual dimorphism and ecological variation are considered.

789 citations

Journal ArticleDOI
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.

706 citations

Journal ArticleDOI
TL;DR: It is concluded that the evidence for the ecological aspect of character displacement is weak and the principal ideas in the original definition given by Brown & Wilson (1956) are retained.
Abstract: Consideration of the possibilities and difficulties of detecting character displacement leads to a re-definition of the phenomenon; character displacement is the process by which a morphological character state of a species changes under Natural Selection arising from the presence, in the same environment, of one or more species similar to it ecologically and/or reproductively. This incorporates the principal ideas in the original definition given by Brown & Wilson (1956), but eliminates the restriction of making comparisons of the character states of a species in sympatry and allopatry. The evidence for the ecological (competitive) aspect of character displacement is assessed by analyzing in detail the best documented and well publicized examples in the literature. Some of the examples either do not exhibit displaced characters or, if they do, the “displacement” can be interpreted in other and perhaps simpler ways; this applies to the so-called classical case of character displacement, Sitta tephronota and S. neumayer in Iran. Other examples, involving lizards and birds, constitute better evidence for character displacement, but in no single study is it entirely satisfactory. It is concluded that the evidence for the ecological aspect of character displacement is weak.

628 citations

References
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Book
01 Jan 1954

3,086 citations

Book
01 Jan 1934
TL;DR: For three-quarters of a century past more has been written about natural selection and the struggle for existence that underlies the selective process, than perhaps about any other single idea in the whole realm of Biology as discussed by the authors.
Abstract: For three-quarters of a century past more has been written about natural selection and the struggle for existence that underlies the selective process, than perhaps about any other single idea in the whole realm of Biology. We have seen natural selection laid on its Sterbebett, and subsequently revived again in the most recent times to a remarkable degree of vigor. There can be no doubt that the old idea has great survival value.

2,641 citations

Journal ArticleDOI
01 Jan 1971

2,397 citations

Journal ArticleDOI
01 Oct 1958-Ecology
TL;DR: The role of biotic factors in the determination of population densities and population fluctuation of the rice stem borer is considered.
Abstract: Wahrscheinlichkeit-Rechnung. Proc. Tokyo Mathem. Phys. Soc., 2nd Ser., 8: 556-564. Miyasita, K. 1955. Some consideration on the population fluctuation of the rice stem borer. (In Japanese.) Bull. Nat. Inst. Agr. Sci., Japan, C, 5: 99-109. Schwerdtfeger, F. 1935. Uber die Populationsdichte von Bupalus piniarius, Panolis flammea, Dendrolin is pini, Sphinx pinastri und ihren zeitlichen Wechsel. Z. Forst-u. Jagdwesen, 67: 449-482, 513-540. . 1954. Grundsitzliches zur Populationsdynamik der Tiere, insbesondere der Insekten. Allgem. Forst-u. Jagdzeitung. 125: 200-209. Smith, H. S. 1935. The role of biotic factors in the determination of population densities. T. Econ. Ent., 28: 873-898.

1,420 citations

BookDOI
02 Mar 1959
TL;DR: From the combination of knowledge and actions, someone can improve their skill and ability and this will lead them to live and work much better.
Abstract: From the combination of knowledge and actions, someone can improve their skill and ability. It will lead them to live and work much better. This is why, the students, workers, or even employers should have reading habit for books. Any book will give certain knowledge to take all benefits. This is what this evolution above the species level tells you. It will add more knowledge of you to life and work better. Try it and prove it.

929 citations