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LEVELS OF SELECTION - Answer all of them What then is the...

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LEVELS OF SELECTION For natural selection to proceed there must be heritable variation in phenotypes and the variation in phenotype must be associated with differential survival and/or reproduction, i.e., there must be differential fitness . By inference then, any entities exhibiting heritable variation in rates of reproduction can evolve . We need not restrict our thinking to "individuals" in "populations" in the traditional senses of these words. Nature is organized in a hierarchical fashion. In terms of entities that can be heritable we can consider genes, chromosomes, genomes, individuals, groups, demes, populations, species , etc. Each of these entities meets the requirements of units that can be acted upon by selection. At which level(s) does selection act?
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Unformatted text preview: Answer: all of them. What then is the important unit of selection? Answer: it depends. First, some historical context. Serious consideration of a unit of selection other than the individual was advanced by V. C. Wynne-Edwards (1962, Animal Dispersion in Relation to Social Behavior ). Populations have their own rates of origination and extinction and selection could thus operate at the level of the group. Idea based on observation that many species tend to curb their reproductive rate/output when population densities are high. This behavior would favor groups that exhibited the behavior and select against those that did not; i.e., there would be group selection ....
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