Quest 4

Question 1

Law of large numbers

Answer 1

as the size of a random sample increases, realized frequencies will be close to expected frequencies

Question 2

genetic drift

Answer 2

random fluctuation in allele frequencies due to sampling effects in small populations

Question 3

Wright-Fisher Model

Answer 3

Like HWE but relaxes the infinite population size assumption

Question 4

Wright-Fisher Model assumptions

Answer 4

1. NS is not acting on traits in question
2. Mating is random
3. No mutation
4. No migration

Question 5

selectively neutral

Answer 5

alleles with no fitness difference between them, NS does not act on the frequencies of these alleles

Question 6

observed heterozygosity

Answer 6

fraction of individuals in the population that are heterozygous at the given locus

Question 7

expected heterozygosity

Answer 7

fraction of heterozygotes expected under HWE model given the allele frequencies in a population

Question 8

Ne

Answer 8

effective population size

Question 9

Effective population size

Answer 9

The number of individuals in a population that are actively breeding

Question 10

population bottle neck

Answer 10

brief period of small population size

Question 11

founder effect

Answer 11

change in allele frequencies from sampling effects when a small number if individuals from a large population colonize a new area

Question 12

leading edge expansion

Answer 12

form of drift: founder effects cause reduced genetic diversity in a newly colonized area

Question 13

He

Answer 13

heterozygosity

Question 14

neutral theory of molecular evolution

Answer 14

biologists look at DNA, RNA and amino acid sequences and how they change over time as opposed to phenotype

Question 15

assumptions of neutral theory of mol evolution

Answer 15

1. most variation in a pop. is selectively neutral.
2. most change in DNA and amino acid sequence are selectively neutral

Question 16

substitution

Answer 16

-new allele arises from mutation and is subsequently fixed in the population
-MOST SUBTITUTIONS ARE NEUTRAL NOT MOST MUTATIONS

Question 17

mutation

Answer 17

a change in the genes DNA sequence to produce something different

Question 18

Pseudogenes

Answer 18

nonfunctional, untranslated segment of DNA that arise from previously functional segment and show evolutionary history as they are derived from known homologous genes

Question 19

positive selection

Answer 19

promotes the spread of beneficial alleles, beneficial allele will be favored in the population

Question 20

purifying selection

Answer 20

minimizes the spread of deleterious alleles, deleterious alleles will be selected against in a poulation

Question 21

Molecular clock

Answer 21

DNA and protein sequences that evolve constantly over time among different organisms

Question 22

equidistant principle

Answer 22

if molecular changes are constant, members of a clade should be equidistant from the outgroup

Question 23

Coalescent time

Answer 23

number of generations to go back for a population to be reduced to two parental lineages. RECENCY OF COMMON ANCESTRY

Question 24

polygenic trait

Answer 24

trait that is affected by many genes simultaneously

Question 25

additive genetic effects

Answer 25

alleles of single genes combine to equal the sum of their individual effects

Question 25

Latent variation

Answer 25

-So much variation within populations that not all possible genotypes could be represented -selection shifts allele frequencies even in the absence of mutations

Question 26

epistasis

Answer 26

effect of a gene mutation is dependent on presence or absence of mutations in one or more other genes

Question 27

haplotype

Answer 27

Set of gene copies that tend to be inherited together

Question 28

Physical Linkage

Answer 28

two genes are located on the same chromosome

Question 29

linkage disequilibrium

Answer 29

-non-random association of alleles at different loci -loci in LD when frequency of association is higher or lower than what would be expected.

Question 30

genetic hitchhiking

Answer 30

when an allele changes frequency because it is near another gene that is undergoing a selective sweep and that is on the same DNA chain

Question 31

background selection

Answer 31

loss of surrounding alleles when a deleterious mutation is selected against

Question 32

selective sweep

Answer 32

advantageous mutation reduces variation in linked sites as it increases in frequency in the population

Question 33

3 consequences of genetic drift

Answer 33

1. allele frequencies fluctuate over time even in the absence of NS 2. some alleles are fixed and some lost, the fraction of heterozygotes in pop decrease over time 3. separate populations diverge allele frequencies

Question 34

New Zealand Snappers

Answer 34

small effective population size. Have a population size of around 3 million fish but only around 200 of them can reproduce, so their Ne is 200

Question 35

divergence between populations of Lava Lizards

Answer 35

population subdivision: limited or no gene flow between subpopulations of a larger population

Question 36

Manx cats

Answer 36

founder effect: prevalence of the M allele on the Isle

Question 37

Northern Elephant Seal

Answer 37

population bottleneck: causing low levels of heterozygosity, skewed reproductive success

Question 38

Spruce trees in leading edge expansion

Answer 38

two hallmarks for genetic drift: low diversity within, high diversity between

Question 39

selection and drift interactions

Answer 39

selection and drift are not mutually exclusive, selection must be strong to reach fixation due to drift on the population.

Question 40

Neutralist and Selectionist debate

Answer 40

dispute on weather drift or selection is the primary driver of evolutionary change.

Question 41

Do molecular clocks work?

Answer 41

useful when comparing a single locus over a short time for closely related organisms

Question 42

effects of population size on coalescence

Answer 42

coalescence occurs more quickly in smaller populations compared to larger populations

Question 43

effects of selection on coalescence

Answer 43

selection drives the alleles to fixation quickly. When under positive selection coalescence occurs more quickly.

Question 44

antibiotic resistance and compensatory mutations

Answer 44

mutation at one lotus confers antibiotic resistance and a compensatory mutation at a second locus reduces the fitness cost of resistance

Question 45

Most variation seems continuous because…

Answer 45

polygenetic traits are continuous

Question 46

Ways LD can happen

Answer 46

-selection - rate of genetic recombination - genetic drift - system of mating - population structure - genetic linkage

Question 47

How does loss of linkage disequilibrium happen?

Answer 47

meiosis with crossing over and outbreeding (asexual reproduction)