|Monkeys, Apes and Humans
Department of Anthropology, University of Missouri-Columbia
The levels of natural selection
The evolutionary process requires "replicators"—entities that can produce exact copies of themselves, such as genes. Natural selection is the process whereby replicators (genes) outpropagate each other, i.e., differences in the representation or frequency of competing replicators in future generations. Evolution is "blind" and has no predetermined direction. Mutations are random.
Hierarchical organization of life:
Unit of selection = entity that replicates exact copies of itself (Dawkins' "replicators") = genes
Levels of selection = where differential reproduction occurs (e.g., an individual has more offspring than competitors) = "vehicles" for gene replication. Replicators (genes) outpropagate each other as a result of differential reproduction at the levels of selection
Selection is most potent where the rate of differential reproduction is highest—usually the individual level.
Selection can act in different directions at different levels; what increases individual fitness may not increase group fitness; what increases chromosome fitness may not increase individual fitness. Which level wins? That is, at which level is selection most likely to produce "adaptations" ?
Conflicts of interest among the levels of selection
Department of Anthropology
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revised: fall 2004
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