Term
What are the five things that stop evolution?
Also needed for Hardy-Weinburg Equilibrium |
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Definition
No Natural Selection
No Genetic drift
No Gene flow
No Mutation
random mating |
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Term
| What makes Natural Selection special in evolution? |
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Definition
| can cause adaptations by itself |
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Term
Describe Directional Selection
what does it reduce? |
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Definition
phenotype is pushed in one direction
reduced genetic variation |
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Term
| Describe Purifying selection |
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Definition
| When bad alleles are lost |
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Term
Describe Stabalizing Selection
what is reduced? |
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Definition
reduces extremes in a population
no change in average traits
genetic variation is reduced |
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Term
Describe Disruptive Selection
why is it important? |
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Definition
extreme traits are favored
important for speciation |
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Term
Describe Balancing Selection
what causes it? |
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Definition
no alleles are at an advantage
heterozygote advantage
-better fitness than homozygotes
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Term
| When does the heterzygote advantage take place? |
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Definition
1. when environment changes over time
2. When Frequency-dependent selection occurs
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Term
| Describe Frequency-dependent Selection |
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Definition
| When rare alleles are sought after |
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Term
| What does Natural Selection do simply |
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Definition
| it increases fitness and leads to adaptation |
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Term
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Definition
| Changes in allele frequency due to chance |
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Term
| What are two types of Genetic Drift? |
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Definition
1. Bottleneck effect
2. Founder effect |
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Term
| Describe the Bottleneck effect |
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Definition
| when a large population's alleles are suddenly reduced |
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Term
| Describe the Founder effect |
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Definition
| when organisms move from a population, changes allele frequency |
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Term
Describe Gene Flow
effect on fitness and variation?
what does it cause? |
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Definition
movement of alleles from one population to another
can increase or decrease them
allele frequency to equalize |
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Term
| What can mutations do to genetic variation? |
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Definition
| it can increase genetic variation |
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Term
| Describe deleterious alleles |
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Definition
| alleles that lower fitness |
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Term
| What is the ultimate source of genetic variation? |
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Definition
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Term
| describe effects of inbreeding |
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Definition
| affects genotype frequency but not allele frequency |
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Term
Describe Inbreeding Depression.
Why does it have that affect? |
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Definition
| fitness is decreased because of an increase in homozygous recessive individuals |
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Term
| Describe Sexual Dimorphism |
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Definition
| any trait that varies between two forms |
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Term
| What can Genetic Drift lead to? |
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Definition
| fixation or loss of alleles |
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Term
| If you decrease genetic variation in a population, what is true about surrounding populations? |
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Definition
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