| A | B |
|---|
| fossil | preserved remains of an ancient organism |
| biogeography | study of geographical distribution of organisms and fossils on Earth |
| natural selection | organisms best suited to the environment have an advantage in nature |
| adaptation | a trait that makes an individual successful in its environment |
| fitness | ability of an organism to survive and reproduce in its environment |
| homologous structure | organs with the same basic structure but different functions |
| analogous structure | organs with the same functions but different structure |
| vestigial structure | organ that ancestors used but no longer serves a function in its descendants |
| coevolution | two species change in close association with each other |
| adaptive radiation | one species evolves into many species when encountering a new environment |
| artificial selection | humans choose the traits they want from a population |
| bell curve | graph showing that most individuals have middle/average phenotypes |
| gene pool | all of the genes in a population |
| allele frequency | proportion of an allele found in a gene pool |
| Hardy-Weinberg genetic equilibrium | genotype frequencies tend to remain the same unless acted upon by outside influences |
| genetic drift | population changes due to chance/random events |
| stabilizing selection | individuals with average phenotypes have the highest fitness |
| directional selection | individuals with an extreme form have highest fitness |
| disruptive selection | type of natural selection where individuals at either extreme have highest fitness |
| speciation | formation of two new species as a result of evolution |
| morphology | study of the form and structure of an individual |
| biological species | population of organisms that can interbreed and produce fertile offspring |
| geographic isolation | physical separation of a population due to geographic barriers |
| reproductive isolation | inability of members of a population to interbreed with members of another related population |
| prezygotic isolation | reproductive isolation that occurs before breeding |
| postzygotic isolation | reproductive isolation that occurs after fertilization |
| gradualism | slow, constant evolution of populations into separate species |
| punctuated equilibrium | long periods of little change in species separated by quick bursts of drastic changes in species |
