| A | B |
|---|
| convergent evolution | occurs as a result of similar pressures; does NOT indicate close relatedness |
| divergent evolution | occurs when organisms branch off from a common ancestor, acquiring different traits as they diverge; DOES indicate close relatedness |
| vestigial structures | anatomical remnants that show past evolutionary history; items are of marginal to no use to modern organism |
| homologous structures | anatomical indicators of relatedness; bat wing and whale flipper are examples |
| analogous structures | anatomical structures that serve similar purposes, but do not indicate relatedness between organisms |
| p | frequency of dominant allele |
| q | frequency of recessive allele |
| p2 | frequency of homozygous dominant individuals |
| 2pq | frequency of heterozygous individuals |
| q2 | frequency of homozygous recessive individuals |
| natural selection | a process by which organisms who are most fit leave the most offspring, thereby changing the make up of the gene pool of the next generation |
| genetic drift | change in allelic or genotypic frequencies in a small population due to chance alone |
| gene flow | the movement of organisms (and their alleles) into or out of a population |
| bottleneck effect | a type of genetic drift; occurs when a disaster indiscriminately kills some members of a population |
| founder effect | a type of genetic drift; occurs when members of a population leave and start their own colony |
| allopatric speciation | occurs when a population is geographically isolated from its parent population |
| speciation | the origin/formation of new species |
| sympatric speciation | the formation of new species without geographic isolation |
| sexual selection | the selection of mates based on some characteristic |
| adaptive radiation | the evolution of many diversely adapted species from a common ancestor |
| archipelago | an island chain |
| punctuated equilibrium | the theory that a new species changes most as it branches off from its parent species and then changes very little after that |
| gradualism | the theory that species slowly appear more and more different from their parent population as they acquire unique adaptations |
| mutation | the only source of new alleles in a species |
| stabilizing selection | favors the average phenotype |
| directional selection | shifts the frequency curve for a certain variation in one direction or another |
| disruptive selection | favors variants of opposite extremes over intermediate individuals |
| heterozygote advantage | the benefit of having one dominant allele and one recessive allele for a particular trait, such as sickle-cell anemia |
| frequency-dependent selection | the selection of a particular trait declines as it becomes more common in a population |
| allele | an alternative form of a gene |
| point mutation | change in only one nucleotide base in a gene |
| population | a group of individuals of the same species that interbreed to produce viable, fertile offspring |
| prezygotic barriers | prevent 2 different species from mating and/or from forming a zygote |
| postzygotic barriers | prevent organisms from 2 different species from producing offspring after a zygote is formed |
| the universal mandate | survive and reproduce! |
| adaptation | a characteristic that enhances an organism's ability to survive and reproduce in its environment |
| biogeography | the geographical distribution of a species |
