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Bio chp 10
| Question | Answer |
|---|---|
| evolution | a change in allele frequencies over a period of time (a genetic change) |
| natural selection | a change in allele frequencies that occurs when individuals with one version of a heritable trait have greater reproductive success than individuals with a different version of the trait. -charles darwin |
| conditions for natural selection | 1. Must be variation for a trait within a population (ex. lady bugs have different colors) 2. That variation must be heritable 3. Individuals with one version of the trait must produce more offspring than those with a different version |
| mechanism of evolution | 1. mutation 2. genetic drift 3. migration 4. natural selection |
| mutation (definition) | An alteration of the base-pair sequence in the DNA of an individual’s gamete- producing cells that changes an allele’s frequency. (mutations only matter evolutionarily when they are from your reproductive cells (gametes) |
| mutation (more info) | -occur when one base pair is messed up -very unpredictable -however necessary for evolution |
| genetic drift (definition) | change in allele frequency due to random chance |
| genetic drift (more info) | -overtime more recessive alleles win causing fixation -fixation: an allele frequency becomes 100% (no variation) -typically affects smaller populations |
| migration (gene flow) | 1. before: two populations same species 2. one species migrates over 3. new type of species that is genetically different |
| survival of the fittest | refers to reproductive output |
| fitness | measure of the reproductive output of an individual with a particular phenotype relative to the reproductive output of individuals of the same species with alternative phenotypes |
| how does fitness occur? | adaption: the process by which organisms become better matched to their environment, the specific features that make an organism more fit |
| factors that prevent perfection | -environment is always changing -Variation is needed as the raw material for selection -There may be different alleles for a trait, each causing an individual to have the same fitness |
| -natural selection co-opt | Traits selected for one function may be co-opted by natural selection for a new function |
| evidence of evolution | 1. fossil records 2. biogeography 3. Comparative anatomy and embryology 4. Molecular biology 5. Laboratory and field studies |
| fossil records | studying physical evidence of an organism that lived long ago |
| biogeography | observing patterns in the distribution of living organisms all over the planet |
| -comparative anatomy | analyzing growth, structure, and development of the body of major groups of organisms |
| Molecular biology | examining life at the level of individual molecules such as DNA and proteins |
| -laboratory and field studies | using the scientific method to observe and investigate evolutionary mechanisms |
| genetic drift (founder effect) | -small number of individuals from a larger population establish a new population (fly example) |
| genetic drift (bottleneck effect) | -population experiences a drastic reduction in size due to environmental events |
Created by:
tcas