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biology-evolution 2
| Question | Answer |
|---|---|
| what does the pinkie stand for? | small population |
| what does the ring finger stand for? | non-random mating |
| what does the middle finger stand for? | mutation |
| what does the pointer finger stand for? | gene flow |
| what does the thumb stand for? | adaptations |
| microevolution | -occurs over a relatively short period of time within a population species -finches |
| macroevolution | -occurs over geologic time above the level of species -fossil record |
| population | consists of organisms of the same species that live in the same area where mating takes place |
| population genetics | the science that focuses on evolution within population |
| gene pool | consists of all the genes of all the members of the population |
| Hardy-Weinburg equilibrium | describes populations in which allele frequencies are not changing |
| what factors are the forces of evolution? | 1. mutation 2. gene flow 3. genetic drift 4. natural selection |
| how do all new alleles first rise? | mutation |
| what mutations matter for evolution in sexually reproducing species? | those that occur in gametes, only these can be passed on to offspring |
| gene flow | occurs when individuals move in or out of a population |
| genetic drift | a random change in allele frequencies that occurs in a small population |
| what are the two special conditions in which genetic drift occurs? | -bottleneck effect -founder effect |
| bottleneck effect | -occurs when a population suddenly gets much smaller -natural disaster -allele frequencies of the survivors may be different from those of the original population |
| founder effect | -occurs when a few individuals start, or found, a new population -allele frequencies of the founders may be different from allele frequencies of the population they left |
| natural selection | -occurs when there are differences in fitness among members of a population -some individuals pass more genes to the next generation |
| what are the three ways natural selection can affect phenotypes? | 1. stabilizing selection 2. directional selection 3. disruptive selection |
| stabilizing selection | -occurs when phenotypes at both extremes of the phenotypic distribution are selected against -narrows the range of variation |
| directional selection | -occurs when one of two extreme phenotypes is selected for -this shifts the distribution toward that extreme -finches |
| disruptive selection | -occurs when phenotypes in the middle of the range are selected against -results in two overlapping phenotypes, one at each end of the distribution -sexual dimorphism |
| sexual dimorphism | refers to differences between the phenotypes of males and females of the same species |
| speciation | the process by which a new species evolves |
| species | a group of organisms that can breed and produce fertile offspring together in nature |
| how can a new species arise? | some members of a species must become reproductively isolated from the rest of the species |
| allopatric speciation | -members of a species become geographically separated from the rest of the species -if they remain separated enough, they may evolve genetic differences -differences prevent them from interbreeding with members of the original species..NEW SPECIES |
| sympatric speciation | new species that arises without geographic separation |
| coevolution | species in symbiotic relationships tend to evolve together, as one species changes, the other species must also change |
| gradualism | -when geologic and climate conditions are stable, evolution may occur gradually -gradual loss of structure -darwin |
| punctuated equilibrium | -when geologic and climate conditions are changing, evolution may occur more quickly -long periods of little change may be interrupted by bursts of rapid change -attributed to a mutation in a few essential genes -fossil record |
| what is in microevolution? | -mutation -selection -gene flow -genetic drift |
| what is in macroevolution? | -speciation -coevolution -gradualism -punctuated equilibrium |
| how can the absolute age of a fossil be found? | -radiometric dating -determining layer of rock where the fossil was found |
| evolutionary/phylogenetic tree | the age and appearances of fossils can be used to place fossils in sequences that often show patterns of changes that have occurred over time |
| phyletic speciation | -abrupt mutations in a few regulatory genes occur after a species has existed for a long period of time -results in the entire species shifting to a new species -relate to punctuated equilibrium |
| divergent speciation | -gradual accumulation of small genetic changes results in subpopulation of a species that eventually accumulate so many changes that the subpopulations become different species -gradualism |
Created by:
amandathornton
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