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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1975 Feb;72(2):646–650. doi: 10.1073/pnas.72.2.646

A theory of evolution above the species level.

S M Stanley
PMCID: PMC432371  PMID: 1054846

Abstract

Gradual evolutionary change by natural selection operates so slowly within established species that it cannot account for the major features of evolution. Evolutionary change tends to be concentrated within speciation events. The direction of transpecific evolution is determined by the process of species selection, which is analogous to natural selection but acts upon species within higher taxa rather than upon individuals within populations. Species selection operates on variation provided by the largely random process of speciation and favors species that speciate at high rates or survive for long periods and therefore tend to leave many daughter species. Rates of speciation can be estimated for living taxa by means of the equation for exponential increase, and are clearly higher for mammals than for bivalve mollusks.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Wright S. Comments on the preliminary working papers of Eden and Waddington. Wistar Inst Symp Monogr. 1967;5:117–120. [PubMed] [Google Scholar]

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