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11 Cards in this Set
- Front
- Back
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describe the process of natural selection |
individuals that have a specific allele that increases their changes of survival are more likely to reproduce and pass on their genes including the beneficial allele = a greater proportion of the next generation inherit the beneficial allele the frequency of the beneficial allele increases from generation to generation |
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what is stabalising selection |
stabilising selection is where individuals with alleles for characteristics towards the middle of the range of characteristics are most likely to survive and reproduce |
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when does stabalising selection occur |
it occurs when the environment is not changing and it reduces the range of possible phenotypes |
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what is directional selection |
this is where individuals with alleles for characteristics of an extreme type are more likely to survive and reproduce |
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what is speciation |
speciation is the development of new species |
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when does speciation occur |
when populations of a species becomes reproductively isolated |
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what is geographical isolation |
this when a population is divided causing some individual to become separated from the main population |
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how do different changes in alleles come about in the separated species |
the species will experience different selective pressures |
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what is a type of selective pressure they might experience |
directional selection could act on their alleles and change the frequency of a particular allele |
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what is another cause of allele change |
mutation will also cause allele frequencies to change |
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what does it mean when individuals from a population have become reproductively isolated |
the change in allele frequency leads to differences accumulating in the gene pools of the separated populations causing changes in phenotype frequencies = eventually individuals will have changed so much they wont be able to breed to produce fertile offspring = reproductively isolated. |
