| A | B |
|---|
| extinction | end of an evolutionary line or the end of a species, family, or larger group of organisms |
| fossil | physical evidence of an organism that lived long ago |
| fossil record | collection of fossils that represents the preserved history of living things on earth |
| intermediate forms | transitions that occur between one "type" of organism and another |
| homologous structures | body parts of different organisms that are different in detail, but similar in general structure and relation to each other |
| vestigial structures | a type of homologous structure that is no longer used as it is in most other organisms that have it |
| species | a group of organisms that can breed with one another and produce fertile offspring in a natural environment |
| speciation | the process by which new species evolve from old ones |
| reproductive isolation | a separation of populations so that they do not interbreed, allowing natural selection to work differently on each group |
| evolution | change in populations of living organisms on planet Earth through time |
| descent with modification | Darwin's idea that species of organisms originate as modified descendants of other species |
| natural selection | the explanation for evolutionary change proposed by Darwin and Wallace |
| absolute (radioactive) dating | a technique utilizing the known rates of decay of radioactive elements to pinpoint the age of a rock or fossil |
| relative dating | method of determining the sequential order of fossils and sediment |
| half-life | the time needed for one half of a radioactive substance to decay |
| sexual selection | selection driven by the competition for mates, considered an adjunct to natural selection |
| adaptation | an inherited characteristic that increases an organisms chance of survival |
| gene pool | all the alleles of all the genes present in a given population |
| gene flow | the introduction of new alleles (or new allele frequencies) from one population to another due to migration |
| genetic drift | changes in allele frequencies of a gene pool due to chance |
| bottleneck effect | change in a gene pool due to large-scale disaster/death in a population |
| founder effect | change in a gene pool due to immigration of part of a population to a new area |
| directional selection | selection that shifts the norm of a population in one direction |
| disruptive selection | selection that increases the extremes in a population |
| stabilizing selection | selection that increases the norm in a population |
| transitional fossil | fossils that illustrate a series of evolutionary changes between two different kinds of organisms |
| mold | an impression left in surrounding rock by a buried organism |
| cast | natural filling of a mold left behind after a fossil has been removed from the rock |
| permineralization | process by which shell or skeletal material is infiltrated by minerals making it dense and heavy |
| analogous structures | parts of different organisms that have similar function, but not the same origin |
| phylogeny | a representation of the evolutionary history of a group of organisms |
| relative frequency | the number of times that allele appears in a gene pool, compared to the number of times other alleles for the same gene occur |
| taxonomy | the practice of naming and classifying organisms |
| population | a community of individuals of the same species |
