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Articles 151 - 156 of 156

Full-Text Articles in Other Ecology and Evolutionary Biology

A Conceptual Framework For Non-Kin Food Sharing: Timing And Currency Of Benefits, Jeffrey R. Stevens, Ian C. Gilby Jan 2004

A Conceptual Framework For Non-Kin Food Sharing: Timing And Currency Of Benefits, Jeffrey R. Stevens, Ian C. Gilby

Jeffrey Stevens Publications

Many animal species, from arthropods to apes, share food. This paper presents a new framework that categorizes nonkin food sharing according to two axes: (1) the interval between sharing and receiving the benefits of sharing, and (2) the currency units in which benefits accrue to the sharer (especially food versus nonfood). Sharers can obtain immediate benefits from increased foraging efficiency, predation avoidance, mate provisioning, or manipulative mutualism. Reciprocity, trade, status enhancement and group augmentation can delay benefits. When benefits are delayed or when food is exchanged for nonfood benefits, maintaining sharing can become more difficult because animals face discounting and …

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Discounting And Reciprocity In An Iterated Prisoner’S Dilemma, David W. Stephens, Colleen M. Mclinn, Jeffrey R. Stevens Jan 2002

Discounting And Reciprocity In An Iterated Prisoner’S Dilemma, David W. Stephens, Colleen M. Mclinn, Jeffrey R. Stevens

Jeffrey Stevens Publications

The Iterated Prisoner’s Dilemma (IPD) is a central paradigm in the study of animal cooperation. According to the IPD framework, repeated play (repetition) and reciprocity combine to maintain a cooperative equilibrium. However, experimental studies with animals suggest that cooperative behavior in IPDs is unstable, and some have suggested that strong preferences for immediate benefits (that is, temporal discounting) might explain the fragility of cooperative equilibria. We studied the effects of discounting and strategic reciprocity on cooperation in captive blue jays. Our results demonstrate an interaction between discounting and reciprocity. Blue jays show high stable levels of cooperation in treatments with …

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Out Of Africa: Origins Of The Taenia Tapeworms In Humans, Eric P. Hoberg, Nancy L. Alkire, Alan De Queiroz, Arlene Jones Jan 2001

Out Of Africa: Origins Of The Taenia Tapeworms In Humans, Eric P. Hoberg, Nancy L. Alkire, Alan De Queiroz, Arlene Jones

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Phylogenetic and divergence date analyses indicate that the occurrence of Taenia tapeworms in humans pre-dates the development of agriculture, animal husbandry and domestication of cattle (Bos spp.) or swine (Sus scrofa) Taeniid tapeworms in Africa twice independently colonized hominids and the genus Homo prior to the origin of modern humans. Dietary and behavioural shifts, from herbivory to scavenging and carnivory, as early Homo entered the carnivore guild in the Pliocene/Pleistocene, were drivers for host switching by tapeworms to hominids from carnivores including hyaenids and felids. Parasitological data provide a unique means of elucidating the historical ecology, foraging behavior …

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Amphicyonidae, Robert Hunt Jan 1998

Amphicyonidae, Robert Hunt

University of Nebraska State Museum: Mammalogy Papers

The Amphicyonidae occur in North America from late Eocene (~40 Ma) to early late Miocene (~9 Ma), a span of 31 million years. In the North American land mammal biochronology, this diverse family extends from the Duchesnean to the end of the Clarendonian and is especially well represented in the Miocene (~5-24 Ma). In the Old World, amphicyonids survive no longer than in North America: The last European records are Vallesian (Dinotheriensande, Mainz Basin, Germany, Kuss, 1965, Tobien, 1980; Vallés-Penédes Basin, Spain, Crusafont-Pairó and Kurten, 1976), and the last representative may occur at about 9 Ma at Kohfidisch, Austria (latest …

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Areographic Representation Of Faunal Characteristics Through A "Second Order" Relational Approach, Charles H. Smith Aug 1983

Areographic Representation Of Faunal Characteristics Through A "Second Order" Relational Approach, Charles H. Smith

DLPS Faculty Publications

Areographic analysis has traditionally depended on primary data consisting of location-specific tallies of presence or absence of given forms. In the present work, an alternate manner of representing distributions is suggested. Regional units are first established, and presence and absence of the forms under consideration in these units is noted. The relation of the biota at any given point location to all others is then established through examination of the former's characteristics of inclusion in the latter. This is accomplished by detailing regional level trends of inclusion and setting up a "second-order" distribution of associations. Two kinds of descriptive information …

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Evaporative Water Loss In Two Northwest Snakes: Pituophis Catenifer And Crotalus Viridis, Donald R. Woolery Jun 1971

Evaporative Water Loss In Two Northwest Snakes: Pituophis Catenifer And Crotalus Viridis, Donald R. Woolery

All Master's Theses

A study by Gans, Krakauer and Paganelli (1968) dealt with twenty-six species of snakes representing five families. They found that the "rate of water loss was proportional to surface area" and that water loss correlates with the aridity of the selected habitat. No comparative information resulting from the direct separation of the pulmonary and cutaneous avenues of water loss is currently available. Also, no direct comparisons of this separation in sympatric species are available. These comparisons are the basis for this study.

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