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Pop. Genetics &Spec.
Population Genetics and Speciation
| Question | Answer |
|---|---|
| results from immigration and emigration | gene flow |
| does not apply when evolutionary forces act on a population | Hardy-Weinberg principle |
| can result from a small group being separated from the main population | genetic drift |
| one of the most powerful agents of genetic change | natural selection |
| range of phenotypes becomes narrower; more individuals in the middle range | stabilizing selection |
| All mutations: | Result in genetic changes, result in genotypic changes, and cause emigration |
| Not all mutations: | Result in phenotypic changes |
| Actual proportions of homozygotes and heterozygotes can differ from Hardy-Weinberg predictions because of: | the occurrence of mutations, nonrandom mating among individuals, and genetic drift within the population |
| The movement of alleles into or out of a population is called: | gene flow |
| Cheetahs are in danger of extinction because of the effects of: | genetic drift |
| Natural selection shapes populations by acting on: | phenotypes |
| Allele frequency is least affected by: | mutations |
| The type of selection that eliminates one extreme from a range of phenotypes is called: | directional selection |
| The Hardy-Weinberg principle applies to all populations as long as evolutionary forces are not working, and | the population is large enough that its members are not likely to mate with one another |
| A demographer studying the adult height in males finds that more men are of average height now than 100 years ago, and there are fewer men who are very short or very tall. What may explain this trend? | stabilizing selection |
| When directional selection eliminates one extreme from a range of phenotypes, the alleles promoting the extreme trait: | become less common in the population |
| Scientists studying the remains of extinct dinosaurs would use what to determine whether or not the remains were different species? | the morphological concept of species |
| Two closely related species of salamanders that live in the same area, but mate at different times of the year would: | have prezygotic isolation |
| Explain how stabilizing selection decreases genetic diversity: | Stabilizing selection allows individuals with the average form of a trait to survive. This means there wouldn't be any extreme forms of the trait and the traits would all be the same with no genetic differences. |
| What are the three major ways variations in genotype can occur? | Mutations, recombination, and the random pairing of gametes |
| What type of selection has a graph that looks like a hill then a valley then a hill? | disruptive selection |
| What assumptions form the basis for the Hardy-Weinberg genetic equilibrium? | No net mutations, no entering or leaving a population, large population, random mating, and no selection |
| What is genetic drift? | The changing of allele frequencies caused by random events or chance |
| Explain the difference between allopatric and sympatric speciation: | Allopatric speciation is a result of geographic isolation and sympatric speciation is a result of reproductive isolation. |
Created by:
smorse