Term
| What happens with HW when we have three alleles? |
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Definition
Nothing, you just have another letter
p+q+r=1
(p+q+r)2
p2+2pq+2pr+2qr+q2+r2 |
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Term
| what do we call gametic genotypes? |
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Definition
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Term
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Definition
| genes for two or more traits located on the same chromosome |
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Term
what is haplotype bias?
give a very general example |
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Definition
certain alleles at different loci tend to be associated with one another
for example: an A1 allele may be more associated with a B1 allele at a different loci than it is with B2 |
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Term
| What's the difference between haplotype bias and linkage disequilibrium? |
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Definition
Haplotype bias means that certain genotypes at loci on the same chromosome tend to be associated with one another more frequently than other genotypes. For instance, the AB genotype might be more common than aB, Ab, or ab and it
might be because A and B, when together, have higher fitness than the other genotypes. Linkage disequilibrium is the end product of haplotype bias because the ABAB genotype occurs more frequently than expected. Neither locus will be
at HW equilibrium, hence linkage disequilibrium. |
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Term
With out haplotype bias, how will linked genes behave?
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Definition
the will act pretty much unlinked and have the usual
p2+2pq+q2 behavior |
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Term
| What is special about the European primrose? What is this an example of? |
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Definition
The European primrose is an example of haplotype bias or linkage disequalibrium.
Remember: on a flower there is the stigma/style thing that has the ova at the bottom, then there are anthers.
The European primrose has two linked genes for stigma/style length and anther length. (A-low, a-high and
G-short and G-high for the style).
Selecting for a style and anther that are the same length allows for advantagoeus selfing during times when pollinators are less available.
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Term
| Describe the breakdown of linkage disequalibrium |
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Definition
Let's say you've got this popn of ALL A1A1B1B1 and A2A2B2B2. This popn is the result of some linkage disequalibrium that always puts the 1s and 2s together.
Okay. So in this popn the possible gametes are A1B1 and A2B2. That give us possible typical genotypes of the first generation to be A1A1B1B1
A1A2B2B2
A1A2B1B2
Let's say the A loci is at the tip of the chromosome. Let's say every now and then there is some XO at the tip of the two original A1B1 and A2B2 chromes that were contributed during sex. We have new gametic possibilities: A1B2 and A2B1 to go along with our old A1B1 and A2B2.
These 4 gametic possibilities give us 9 possibilities for the next generations:
A1A1B1B1
A1A2B1B1
A2A2B1B1
A1A1B1B2
A1A2B1B2
A2A2B1B2
A1A1B2B2
A1A2B2B2
A2A2B2B2
We have gone from having 2 genotypes in a population to 9 as the result of one XO event. |
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Term
when does XO occur?
what else is it called? |
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Definition
happens during metaphase 1 of meisosis
aka Recombination |
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Term
| what is recombination rate? |
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Definition
how frequently chromosomes break and cross-over
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Term
| graph of recombination rate (shape only, ignore the labels, they are incorrect) |
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Definition
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Term
| How doe we mathmatically describe disequilirium? |
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Definition
Coefficient of Disequilibrium
D=(p1q1xp2q2) - (p1q2 x p2q1)
max D = .25
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Term
what are the labels on a recombination rate graph?
how does r describe recombination? |
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Definition
x axis = generations
y axis = coefficient of disequilibrium
r=0 means no recombination
r=.5 means rapid recombination
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Term
what determines the rate at which disequilibrium goes to zero? |
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Definition
interloci distance
recombination rate |
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Term
| how does interloci distance effect D? |
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Definition
| greater distance --> fastor D (disequilibrium) goes to zero |
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Term
what are both types of mimcry examples of? what are the two types...describe them with examples.
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Definition
examples of NS acting on allelic combinations and creating likage disequilibrium
1. batesian mimicry: nontoxic mimcs a *toxic model
*monarch vs viceroy butterfly
*papilio memnon vs other butterflies
*coral snakes (micrurus) vs pliocercu
2. mullerian mimicry: toxic things look like eachother
yellow jacket and killer wasp |
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Term
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Definition
| advertisement of noxiousness |
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Term
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Definition
several alleles @ several loci acting as a single gene with many phenotypic effects
ex. mimics/models |
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Term
| why are recombinants rare with supergenes? |
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Definition
| predators recognize it and the org with supergenes doesn't live long enough to establish it's genes |
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