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Journal Article

Group Selection, Sex, and Fossils

Leigh Van Valen
Evolution
Vol. 29, No. 1 (Mar., 1975), pp. 87-94
DOI: 10.2307/2407143
Stable URL: http://www.jstor.org/stable/2407143
Page Count: 8
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Group Selection, Sex, and Fossils
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Abstract

The loss of sex and other recurrent unidirectional evolutionary trends can be treated as a simple equilibrium balanced by group selection. Genera of large mammals and large foraminiferans have a selective disadvantage of 0.02 to 0.05 per million years. The components of this selection act in opposite directions and in each case are much larger than the total selection, suggesting that most interspecific competition is with organisms of rather similar size. A related conjecture is disproved. Group selection is an important cause of evolution, including that of man.

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