| A | B |
|---|
| evolution | process by which species arise and change over time |
| paleontology | the study of fossils |
| fossils | traces of organisms that existed in the past |
| natural selection | a mechanism by which individuals that have inherited beneficial adaptations produce more offspring than other individuals |
| fitness | the reproductive success of an individual relative to a measure of the ability to survive and produce more offspring relative to other members of the population |
| adaptation | a feature that allows an organism to better survive and reproduce in its environment |
| artificial selection | when humans change a species by breeding it for certain traits (dogs, plants, etc) |
| transitional fossils | have similarity to two groups that in the present day are classified separately |
| homologous structures | similar structures derived from a common ancestor (forelimb bones) but have different functions |
| analogous | anatomical structures with similar function but different evolutionary paths (wings in birds and butterflies) |
| population | a group of organisms of a single species living together in the same area |
| gene pool | alleles of all genes in all the individuals in a population |
| allele frequency | percentage (relative amount) of each allele in a population's gene pool |
| Hardy-Weinberg equilibrium | A stable non-evolving state caused by no mutation, no migration, large population size (no genetic drift), random mating, and no natural selection. |
| Hardy-Weinberg principle | Allele frequencies can be expressed as p + q =1 and genotype frequencies by p^2 + 2pq+q^2 = 1 |
| mutation | a random change in the DNA sequence (a source of new genetic variation). |
| Gene flow | the movement of alleles between populations (immigration, emigration) |
| Genetic drift | refers to changes in allele frequencies of a gene pool due to chance events. |
| Bottleneck effect | A type of genetic drift in which the loss of genetic diversity is due to natural disasters, disease, overhunting, or habitat loss. |
| Founder effect | A type of genetic drift in which variation is lost when a few individuals break away from a large population to found a new population. |
| inbreeding | mating between relatives (side-effect of small population size--genetic drift) |
| non-random mating (also called sexual selection) | occurs when individuals choose a mate with a preferred trait |
| stabilizing selection | occurs when an intermediate phenotype is favored in the given environmental conditions. |
| directional selection | occurs when an extreme phenotype is favored, and the curve shifts towards one of the extremes |
| disruptive selection | occurs when two or more extreme phenotypes are favored over the intermediate phenotype |
| sexual selection | certain traits increase mating success |
| speciation | splitting of one species into two or more species that can no longer successful interbreed |
| taxonomist | a scientist who classifies organisms into groups |
| biological species concept | relies primarily on reproductive isolation to identify different species |
| allopatric speciation | the eventual result of populations that have become separated by a geographical or other form of physical barrier |
| sympatric speciation | speciation in the same geographical location due to changes in behavior, diet, microhabitat |
| geologic timescale | divides the history of the Earth into eras and then periods and epochs |
| phylogeny | evolutionary "family tree" that represents the evolutionary history of taxa |
| common ancestor | at the base of each branch of the phylogenetic tree |
| ancestral traits | traits found in a common ancestor |
| derived traits | those not found in a common ancestor, important for clarifying evolutionary relationships |
| cladistics | method that uses shared, derived traits to develop a hypothesis of evolutionary history |
| cladogram | a phylogeny constructed with cladistic methods |
| clade | a common ancestor and all of its descendant lineages |
| outgroup | taxon that is used to determine the ancestral and derived traits of characters in the ingroup |
| molecular clock | mutations occur at a constant rate and can be used to determine how long two organisms have been evolving independently |
| variation | difference in the physical traits of an individual from other individuals in the population |
| descent with modification | Darwin's term for evolution by the process of natural selection |
| comparative embryology | closely related organisms (for example vertebrates) have similar structures in early embryonic development, suggesting common ancestry |
| vestigial structures | remnants of organs or structures that had a function in an ancestor (wisdom teeth, appendix) |
| molecular evidence | organisms with few differences in DNA or proteins are more closely related |
| extinction | the elimination of a species from the Earth (dinosaurs) |
| relative dating | estimates the time by comparing the placement of fossils in different layers of rock (oldest at the bottom) |
| absolute (radiometric) dating | a technique using the decay of radioisotopes to calculate the age of rocks, fossils. |
| cyanobacteria | bacteria that can carry out photosynthesis and put oxygen in the atmosphere |
