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29 Cards in this Set
- Front
- Back
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What is the chi- square equation?
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x^2= SUM of (O-e)^2 / e
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To determine "e" what must we assumer?
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NO BIAS
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"e" values are based upon what?
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null hypothesis
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What does the null hypothesis mean?
What does it provide? |
expected, randomness, chance prevails
It provides a reference for comparison |
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What is the direct relationship in Chi-square?
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As (O-e) increases, x^2 increases
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If you reject the null hypothesis, your data is what?
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statistically significant
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The Hardy-Weinberg equilibrium (or theorm) addresses what?
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Addresses allele frequency changes (with time) within a population
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Give an example of a null hypothesis
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Hardy Weinberg theorm
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For the Hardy Weinberg to hold, the following assumptions must be true:
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random mating
no mutation no migration infinite population size no natural selection (this is all respect to alleles at the locus in question) |
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Hardy Weinberg Equilibrium
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no change in allele frequencies over time
(can also be used to calculate expected genotype frequencies) |
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What are the consequences of the Hardy- Weinberg Equilibrium?
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1. no evolution will take place (i.e. no allele frequency changes)
2. can predict the abundance of each genotype |
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Problem.
Allele A & a are at the same locus. freq (A) = p = .7 freq (a) = q = .3 p+q=1 allow random mating. what are the genotype frequencies? |
AA Aa aa
1=p^2 + 2pq + q^2 |
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Problem
Given at a particular locus a population has 3 alleles: a,b,c frequencies are a(.5) b(.3) and c(.2) assume HW model applies 1. what will be the freq of ac genotype in the next generation? 2. "...." of the b allele in the fourth generation |
1. 2ac= 2(.5)(.2)=.2
2. .3 because frequencies do not change |
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What are the five mechanisms of Microevolution
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1. non-random mating
2. genetic drift 3. migration gene flow 4. mutation 5. natural selection |
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Two types of non-random mating
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1. assortative
2. inbreeding |
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What is assortative (a type of non-random mating)
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when similar phenotypes (within a population) tend to mate with eachother
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What is inbreeding (a type of non-random mating?)
give examples (2) |
mating with relatives
ex. among siblings- some parasitic wasps plant species inbreed (have both male and female parts) |
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if inbreeding is deleterious, then what occurs?
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reduction in fitness
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inbreeding/selfing promotes what?
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homozygosity
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When is homozygosity a problem?
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if a is a deleterious
allele-> aa |
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Give an example of an outbreeding depression
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the ibex
when czech ibex became extinct they brought some ibex from Austria which thrived. Then the got ibex from Turkey which had an earlier mating and breeding season than the Austrian ibex. population died out |
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Small populations get random effected gene frequencies due to what 2 things?
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1. genetic drift
2. population bottlenecks |
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what happens in population bottlenecks?
give two examples |
loose genetic diversity
ex. cheetahs, and fragmented populations |
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Three founder effects
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islands
colonizers zoo populations |
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Genetic drift
more likely where? |
random change in allele frequencies
more likely in places with small populations |
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When one allele remains at a locus
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fixation
(an emergent property of a population) |
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How do populations effect changes in allele frequency
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very large population- the freq of allele wont change much
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Inbreeding leads to what?
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a change in GENOTYPE frequency
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genetic drift leads to what?
give example of genetic drift |
change in ALLELE frequency
ex of genetic drift- scurvy in humans genetic drift leads to -> evolution, not necessarily adaptation |
