Article Abstract:
Categories of cooperation among unrelated indviduals include group-selected behavior, reciprocal altruism and by-product mutualism. In group-selected behavior, the mechanism for cooperation is the deme structure which requires differential productivity of trait groups. Score-keeping is the mechanism behind reciprocal altruism and requires high expected interactions between individuals. In by-product mutualism, the mechanism is the common enemy of a sufficiently adverse environment and requires the boomerang factor or the chance that noncooperators become victims of their own cheating. These mechanisms operate alone or together in widely divergent taxa.
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Article Abstract:
Adaptation is a central concept in contemporary evolutionary biological studies. However, the inability to distinguish between evolutionary historical definitions of adaptation to those addressing issues about phenotype existense has led to questions regarding the importance of natural selection in molding phenotypes. A nonhistorical definition of adaptation which emphasizes the relativity of the concept, provides a framework for phenotype identification and separates adaptation fromthe evolutionary apparatus is developed to remedy this situation.
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Article Abstract:
A theory that links decline in sperm performance due to cell-age with inheritable sperm and diploid traits is presented. Evidence to show the role of sperm age-related variation in behavioral ecology and evolutionary biology is discussed.
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