structures that have similar functions and superficially similar appearance but very different anatomies, such as the wings of insects and birds. The similarities are the result of similar environmental pressures rather than a common ancestry.
a selective breeding procedure in which only those individuals with particular traits are chosen as breeders; used mainly to enhance desirable traits in domesticated plants and animals; may also be used in evolutionary biology experiments.
the independent evolution of similar structures among unrelated organisms as a result of similar environmental pressures; see analogous structures.
(1) the theory that all organisms are related by common ancestry and have changed over time; (2) any change in the proportions of different genotypes in a population from one generation to the next.
the remains of a dead organism, normally preserved in rock; may be petrified bones or wood; shells; impressions of body forms, such as feathers, skin, or leaves; or markings made by organisms, such as footprints.
structures that may differ in function but that have similar anatomy, presumably because the organisms that possess them have descended from common ancestors.
unequal survival and reproduction of individuals with different phenotypes; causes better adapted phenotypes to become increasingly common in a population.
all the members of a particular species within an ecosystem, found in the same time and place and actually or potentially interbreeding.
a structure that serves no apparent purpose but is homologous to functional structures in related organisms and provides evidence of evolution.