| Macroevolution | large scale modifications that occur over long time periods and produce new species |
| Mass Extinction | one of a brief period of time during which large numbers of species disappeared |
| Relative Dating | A procedure for comparing the amount of a radioactive isotope and its decay product to determine the age of a geologic specimen |
| Radioactive Dating | A method of determining the age of an object by measuring the amount of a specific radioactive isotope it contains |
| Microevolution | small scale modifications that occur over short periods and result in a change in gene frequency within a population |
| Homologous | similar feature originated in a shared ancestor |
| Vestigial | name of the functionless structure that was functional in an ancestral species |
| Fitness | a measurement of the ability of a species to respond to the pressures of natural selection and produce the most viable offspring |
| Adaptation | an inherited trait that increases an organisms chance of survival in a particular environment |
| Survival of the Fittest | the individuals capable of producing the most viable offspring in a population |
| Natural Selection | the process by which organims with favorable variations reproduce at higher rates than those without such variations |
| Evolution | descent with modification |
| Convergent Evolution | the process by which unrelated species become more similar as they adapt to the same kind of environment |
| Divergent Evolution | the process of two or more related species becoming more and more dissimilar |
| Adaptive Radiation | an evolutionary pattern in which many species evolve from a single ancestral species |
| Disruptive Selection | a type of natural selection in which individuals with two extreme forms of a trait have an advantage |
| Directional Selection | individuals that display a more EXTREME form of a trait have greater fitness |
| Stabilizing Selection | a type of natural selection in which the average form of a trait causes an organism to have an advantage in reproduction |
| Gene Pool | all the genes for all of the traits in a population |
| Relative Frequency | the abundance of one form of a gene or trait compared to an alternative form of the same gene or trait. |
| Genetic Drift | a shift of allele frequencies in a population due to random chance |
| Founder Effect | occurs when a new population is established by a relatively few individuals |
| Hardy-Weinberg Principle | principle stating the stability of gene frequencies across generations |
| Genetic Equilibrium | alternate forms of a trait have equal frequencies ex. p=50% q=50% |
| Reproductive Isolation | the inability of formerly interbreeding organisms to produce viable offspring |
| Analogous | structures that are similar in appearance and function but have different ancestral origin |
| Speciation | the formation of a new species |
| Punctuated Equilibrium | a theory that speciation occurs during brief periods of rapid genetic change |
| Coevolution | the mutual modification of two different species interacting with each other |
| Sexual Selection | the preferential choice of a mate based on a specific phenotypic trait |
| Uniformitarianism | principle that says geological structure of the earth resuited from cycles of observetable processes and that the same process operate continually through time |
| Endosymbiosis | a theory of the evolution of eukaryotes by the formation of a mutualistic relationship between two prokaryotes |