Advances in the Study of Behaviour: v. 10 by Jay S Rosenblatt

By Jay S Rosenblatt

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Last, there are processes that store and propagate selected variants within the population, the propagating processes including both retrieval and transmission systems. For convenience we shall refer to all three subprocesses as collectively constituting a “generate-test-regenerate” (g-t-r) heuristic, but in doing so it should be clearly noted that the regenerate phase in this heuristic also represents the next generate phase of a continuously ongoing process. The regenerate phase must, in fact, be taken to refer to both the retrieval and propagation of previously selected variants, and to the generation of some new variants that as yet still have to be acted on by any subsequent test phase selection pressures.

C . PLOTKIN A N D F. J . ODLING-SMEE members of any intrabreeding population. However, it is necessary to describe more fully one of the fundamental characteristics of this unit. At any given moment a population consists of a set of currently living organisms. Each of these organisms, however, is itself organized around a genotype-phenotype dichotomy. The chief significance of this dichotomy is that it allows adaptations to occur at either the genotypic or the phenotypic level. Since natural selection acts on phenotypes and not on genotypes, the adaptations that may occur at either of these two levels are potentially equally effective determinants of the fitness of the organism, and therefore of the population.

This constraint arises from the time lag that is inherent in every tracking process, and in the specific case of phylogenesis, results from the time it takes for members of a population to regenerate. Every organism that reproduces, whether by way of gamete production and exchange, or by some more primitive means, produces offspring that themselves take time to develop to the point where they in their turn become reproductively competent. Therefore, a period of time must 20 H. C . PLOTKIN A N D F.

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