1975/02/01 by Steven M. Stanley, María A. Vizcaíno Villanueva · 9 citations
Arts and Humanities · Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · Social Sciences · #Evolution and Genetic Dynamics #Evolution and Paleontology Studies #Evolutionary Game Theory and Cooperation #Historical Art and Architecture Studies #Historical Studies of Medieval Iberia #Medieval and Early Modern Iberia
paper · doi:10.1073/pnas.72.2.646
openalex publication_date 2010/01/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/23
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.