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Ch 16 Pop Gen & Spec
Ch 16 Population Genetics and Speciation
| Term | Definition |
|---|---|
| allele frequency | Number of a certain allele divided by the total number of alleles of all types in the population |
| allopatric speciation | The formation of new species in populations that are geographically isolated from one another |
| bell curve | distribution of scores in which the bulk of the scores fall toward the middle, with progressively fewer scores toward the "tails" or extremes |
| biological species concept | a species is a population of organisms that can successfully interbreed but cannot breed with other groups |
| bottleneck and founder effect | when a small group of individuals separates from a larger population and expresses genes that were rare in original population |
| directional selection | Form of natural selection in which the entire curve moves, occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve |
| disruptive selection | natural selection in which individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle of the curve |
| emigrant | a species leaving |
| five conditions of HWE | 1)No mutations 2)No emigration/immigration 3) Large population 4) Random mating 5) No natural selection |
| gene flow | change in the gene pool due to the exchange of genes with another population |
| gene pool | all of the alleles of all the individuals within a population |
| genetic drift | change in the gene pool due to chance events smaller population=bigger affect |
| genetic recombination | the result of the processes of meiosis and fertilization alleles are shuffled and dealt randomly |
| geographic isolation | physical separation of a group of individuals from others of the same species |
| gradualism | The theory that evolution occurs slowly but steadily |
| hardy-weinberg equilibrium | the state when gene frequencies are not changing in a population, allelic frequency is constant |
| immigrant | a species coming in |
| microeveolution | a generation to generation change in frequency of alleles |
| morphology | study of form, scientists use structure and appearance to define species |
| mutations | a change in an organisms DNA adds random variation |
| natural selection | change in the gene pool due to differences in survival and reproductive success among the population |
| phenotype frequency | equal to the number of individuals with a particular phenotype divided by the total number of individuals in the population |
| population | a collection of individuals of the same species in a given area whose members can interbreed |
| population genetics | the study of evolution from a genetic point of view |
| postzygotic isolation | reproductive isolation that occurs after members of two different species have mated and produced a hybrid offspring. Such hybrids are usually unable to reproduce (postmating isolation) |
| prezygotic isolation | a barrier to successful breeding that occurs before fertilization, such as differences in mating time or behavior (premating isolation) |
| punctuated equilibrium | The theory that species evolve during short periods of rapid change |
| relative (allelic) frequency | number of times an allele occurs in a gene pool compared with the number of times other alleles occur |
| reproductive isolation | results from barriers to successful breeding between population groups in the same area |
| sexual selection | when individuals select mates based on heritable traits |
| speciation | existing species are essentially changed version of older species |
| species | a group of organisms that share similar characteristics and can interbreed with another producing fertile offspring |
| stabilizing selection | form of natural selection by which the center of the curve remains in its current position, occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end |
| sympatric speciation | when two subpopulations become reproductively isolated within the same geographic area |
Created by:
droesener
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