BIO2008: Lecture 5

  • Created by: LMoney
  • Created on: 10-05-14 20:42
what is expected Heterozygosity? (He)
probability that 2 randomly chosen gametes are different (i.e. heterozygote) (N.B. He is also between 0 and 1)
1 of 26
what does He equal if HW applies and only 2 alleles?
2 of 26
how else can He be calculated?
3 of 26
what are the 2 hierarchical levels of heterozygosity?
within subpopulations: Hs, across all samples (total) HT
4 of 26
what happens if there is no HW equilibrium?
often expected He does not equal observed (Ho), and generally He > Ho
5 of 26
when would He not > Ho?
heterozygote advantage and dissassortive mating
6 of 26
Recap: what could cause there not to be HW?
selection, non-random mating, population structure
7 of 26
what does the HWE model predict?
genotype frequencies from allele frequencies in random mating populations
8 of 26
which theory did Sewall Wright come up with?
theory of isolation by distance- F= Wright's fixation index
9 of 26
how does HWE work?
Reduction average proportion of heterozygotes, relative to expectation under random mating- Use this reduction to estimate the amount of subdivision, i.e. population structure:
10 of 26
what is F (wright's fixation index) a measure of?
differentiation of populations or regions
11 of 26
what does Fst indicate?
fixation index of subpopulations relative to total
12 of 26
how is data often generated now?
PCR polymerase chain reaction
13 of 26
describe PCR
1) even 1 cell is in theory enough 2) contamination can be problem e.g. human DNA 3) non-invasive techniques 4) many applications, different types of markers
14 of 26
what is a microsatellite marker?
Repetitive DNA
15 of 26
what are tandem repeats?
Tandem repeats occur in DNA when a pattern of one or more nucleotides is repeated and the repetitions are directly adjacent to each other
16 of 26
what is satellite DNA?
Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA
17 of 26
which DNA does PCR amplify?
the fragment between primer sites
18 of 26
describe microsatellites?
1) Many loci in every genome 2) Every locus is highly polymorphic: 5 - 30 alleles 3) A combination of several loci identifies every individual (except identical twins) 4) Generally scored as the length of the fragment amplified
19 of 26
why are microsatellites highly polymorphic (variable)?
They mutate more frequently
20 of 26
why do short tandem repeats evolve fast?
1) non-functional: no selection against a mutation 2) many “mistakes” during replication
21 of 26
what is replication slippage (kind of mutation in micro satellite DNA)?
a form of mutation which leads to either a trinucleotide or dinucleotide expansion or contraction during DNA replication
22 of 26
what will Fst values tell us about red squirrel populations (for example)?
1) Genetic variation (differentiation) between populations 2) Therefore: Amount of gene flow between populations
23 of 26
how can dispersal distances be calculated?
by assessing the level of habitat fragmentation that results in populations out of Hardy-Weinberg equilibrium.
24 of 26
Detection of introductions at wide geographic scale use what?
mitochondrial DNA
25 of 26
what do Mitochondrial DNA markers tell you about?
Dispersal of female animals
26 of 26

Other cards in this set

Card 2


what does He equal if HW applies and only 2 alleles?



Card 3


how else can He be calculated?


Preview of the front of card 3

Card 4


what are the 2 hierarchical levels of heterozygosity?


Preview of the front of card 4

Card 5


what happens if there is no HW equilibrium?


Preview of the front of card 5
View more cards


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Lecture 5 resources »