Mechanisms of Evolution (Bio111)

By amgarrett099, Dec 2010

Subjects: global

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What are the mechanisms of evolution?	1. mutation 2. genetic drift 3. natural selection 4. sexual selection 5. gene flow
What are mutations?	Ultimate source of all genetic variation. Changes the genetic code, generating new alleles, which may change into amino acid sequences, which may have phenotypic effects.
What is an allele?	Different forms of a gene.
What is fitness?	Survival and reproductive success.
How do mutations effect fitness generally?	Neutral or deleterious. (slight negative effect) Beneficial mutations are rare.
What is genetic drift?	Causes random changes in allele frequency. Proportions of alleles change by chance.
How does the effect of genetic drift change with population size?	Stronger in smaller populations.
What were Darwin and Wallace's insights on natural selection?	All organisms have the potential for exponential growth. Most populations remain bounded. "Struggle for survival".
What is natural selection?	Traits vary among individuals and are heritable. In every generation, some are better at surviving than others. Predict: traits that improve survival and reproduction should increase in frequency over time.
Significance of "Darwin's finches"?	Birds with larger beaks were more likely to survive.
What is sexual selection?	Intra-sexual: male-male competition. Inter-sexual: female choice.
What is gene flow?	Movements of genes among populations. Tends to oppose the divergent natural selection.

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