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19 Cards in this Set
- Front
- Back
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What is selectionism? |
Most changes will be seen due to selection if we look hard enough |
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What is neutralism? |
The majority of variation is neutral, only some is selective |
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Outline the neutral theory of evolution (Kimura) |
-Organisms gradually accumulate substitutions in DNA and amino acid sequence -Most have no effect on fitness -Neutral allele frequency is determined only be genetic drift and mutation rate -Neutral evolution thus proceeds as a 'molecular clock' ticking at the mutation rate |
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Give two structures capable of mutation |
Genes Chromosomes |
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Give four types of gene mutation |
Substitution Deletion/insertion Point mutation Frame shift
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Give four types of chromosome mutation |
Deletion Translocation Nondisjunction Inversion |
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Mutation rate in humans is 1.6 m/g/g. In drosophila the rate is 0.4 m/g/g. When observed, the rates of mutation appear to be similar. Why? |
When the amount of divisions needed to produce sperm is taken into account it works out similar rates |
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What causes mutations to be lost? |
Random genetic drift (rare) Natural selection (harmful)
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Describe the mutation that gave rise to rifampin resistant bacteria |
Point mutation in rpoB gene of RNA polymerase changing serine to leucine at the 153rd amino acid |
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What is a synonymous mutation? |
No change to protein |
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What is a non synonymous mutation? |
Change to protein |
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What is nondisjunction? |
Non homologous chromosomes fail to separate |
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Describe the mutation that causes cystic fibrosis |
Loss of function of CFTR gene that is expressed in the lungs and prevents bacterial infection |
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How does the concept of heterogenous superiority relate to cystic fibrosis? |
-CFTR protein found in gut -Typohoid bacteria exploits the bacteria to cross into gut -Loss of function prevents infection
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What is stabilising selection? Give one example |
Favours intermediates over extreme phenotypes
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Lake Erie water snakes on the mainland are banded whereas on the islands are unbanded. Why doesn't the unbanded phenotype go into fixation? |
Migration |
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Give two occurrences where random genetic drift has the biggest impact |
Small population size Allele frequency near 0 or 1 |
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What kind of selection is most likely to lead to speciation? |
Diversifying selection |
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What is the founder principle? (Mayr) |
Random genetic drift caused when only a small number of individuals form the next generation i.e alpine wolves |
