The theoretical model of evolution in which species change slowly at a more or less constant rate through time into other species. |
gradualism |
Major evolutionary changes in a population's gene pool, occurring over many generations, resulting in the evolution of new species. | macro evolution |
Small changes in a population's gene pool occurring over a few generations. The accumulation of these changes in allele frequencies over many generations can result in macroevolution. | micro evolution |
The theoretical model of evolution in which species remain unchanged for long periods of time and then at times rapidly change as a result of major alterations in the environment and, subsequently, in natural selection. | punctuated evolution |
The progressive diversification of a species into two or more species as groups adapt to different environments. Natural selection is usually the principle mechanism driving this evolution. |
cladogenesis |
Evolution within a single evolutionary line without the branching of adaptive radiation. This takes place when the members of a species consist of a single breeding population for many generations. Descendent generations experience continuous spontaneous mutations and new directions of natural selection as the environment changes. As generations subsequently replace each other, the gene pool is transformed--i.e., it evolves. |
anagenesis |