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36 Cards in this Set
- Front
- Back
evolution |
the accumulation of inherited changes within a population over time
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1809 |
(jean baptiste lamark) environment gives rise to changes in animals
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1858 (AW) |
alfred wallace - natural selection |
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1831 |
charles darwin - HMA Beagle as a naturalist |
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1858 (CD) |
charles darwin - presented to Linnaean society of London |
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1859 |
charles darwin - on the origin of species |
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charles darwin on the origin of species |
1. species are not immutable ( they change over time - mutable) 2. process that produces these changes natural selection differential reproductive success of individuals different genetic types - different contribution 3. divergent species share common ancestor & have diverges from one another gradually thru time |
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phenotype |
physical expression of genes (observable) |
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genotype |
genetic expression |
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gene |
unit of heredity |
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alleles |
different form of gene |
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gene pool |
sum of alleles in a population |
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allele frequency |
number of certain alleles in a population over sum of alleles in a population |
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genotype frequency |
number of individuals with a given genotype over total number of individuals in a population |
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what is the general idea of the hardy - Weinberg equilibrium? |
1. allele frequency does not change 2. genotype frequency does not change (genetic structure does not change) (what would have to happen for change to occur) |
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what shows that change is occurring in the hardy - Weinberg equilibrium |
derivations from the HW frequency |
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5 essentials about a population to meet the HW equilibrium |
1. random mating 2. pop size very large 3. the genes can't migrate between populations (no gene flow) 4. no mutations (changes in DNA) 5. natural selection cannot exist |
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mutations |
1. germline 2. most are harmful or neutral 3. some are advantageous 4. rates are low (just small deviations from HWE) |
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mutations are the main causes for |
genetic diversity |
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gene flow may change.. |
allele frequencies |
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gene flow |
1. individuals may migrate & breed 2. migrants may add new genetic characteristics to the gene pool of a population change the frequency of certain characteristics already present in the population |
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genetic drift may cause... |
large changes in a small population |
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genetic drift |
1. caused by change in allele frequency by random chance 2. effect is larger in smaller populations 3. it occurs if the population is not infinite in size |
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bottleneck effect |
(lost genetic diversity) |
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founder's effect
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(drosophila - flies) 1. small starting group 2. when a few pioneering individuals colonize a new region, the resulting population will not have all the alleles found among members of the same population |
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non - random mating |
1. sexual selection 2. self-fertilization: non-random mating 3. geographic isolation |
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sexual selection |
the struggle between the individuals of one sex for the possession of another sex |
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functions of natural selection |
1. reduces variation in a population 2. does not change the mean 3. preserves the average phenotype |
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fitness |
reproductive contribution of a phenotype to subsequent generations (relative to other phenotypes)
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stabilizing selection |
average phenotype is more selected and will appear more frequently |
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directional selection |
favors 1 extreme |
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disruptive selection |
favors 2 extremes (extremes are more fit to survive) |
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what impact may migrants have on gene flow?
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1. add new genetic characteristics to a gene pool 2. change frequency of genetic characteristics already present in a population |
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the bottleneck effect and founders effect are examples of |
genetic drift |
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what are the 5 evolutionary mechanisms |
mutation gene flow genetic drift non-random mating natural selection |
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example of natural selection |
English :how well a phenotype allows an individual to survive and reproduce (contribute to the reproductive success of species) |