Natural Selection

Abstract

Abstract Natural selection causes change in the phenotypic composition of a population through the differential birth and death of its members. Natural selection can operate simultaneously at many different levels in the hierarchy of biological organization, from the cellular (gametic selection) to the individual (Darwinian or mass selection), to the population (kin, group, and interdemic selection) as well as to the species or community level. That is, we can consider populations of gametes, cells, individuals, populations (called “metapopulations”), communities, and species as collections of biological entities whose members persist, reproduce, and die as a result of differences in phenotype. Differences in the direction or strength of natural selection at different levels in the biological hierarchy contribute to the origins of biodiversity.