population genetics & natural selection

Question 1

what evolves and what doesn’t?

Answer 1

population evolves but individuals don’t

Question 2

what is a population?

Answer 2

localized group of individuals of the same species

Question 3

what is a gene pool?

Answer 3

the total aggregate of genes (and their alleles) in the population at one time

Question 4

Why might we need to estimate frequencies of genotypes in a population?

Answer 4

1. To predict how many individuals will inherit a genetic disease
2. To estimate the proportion of individuals who are ‘carriers’ of a genetic disease

Question 5

How do we predict genotypes in a population?

Answer 5

Hardy-Weinberg equation

Question 6

what is the allele frequency equation?

Answer 6

Allele frequency - p + q = 1

Question 7

what is the allele frequency equation?

Answer 7

Allele frequency - p + q = 1

Question 8

what is genotypic frequency equation?

Answer 8

Genotypic frequency - p2 + 2pq + q2 = 1

Question 9

how can we predict genotypic frequency in a population?

Answer 9

through allele frequency

Question 10

what are p and q in the Hardy-Weinberg equation?

Answer 10

p = frequency of dominant allele
q = frequency of recessive allele

Question 11

what is pq in the Hardy-Weinberg equation?

Answer 11

heterozygous

Question 12

what happens in an x-linked trait for females and males?

Answer 12

for an x-linked trait:
- females need to be homozygous recessive to get the disease
- males need just one recessive allele

Question 13

what are ways allele frequency can change by?

Answer 13

• Non - random mating
• Random Genetic Drift
• Bottleneck Effect
• Founder Effect
• Natural Selection
• Gene Flow or Migration
• Mutation

Question 14

what are two different types of nonrandom mating?

Answer 14

• assortative mating
• inbreeding

Question 15

what is assortative mating?

Answer 15

attraction phenotype similar to your own

Question 16

what is disassortative mating?

Answer 16

goes out of way to not get similar phenotype to your own

Question 17

what is random genetic drift?

Answer 17

A random change in allele frequencies due to sampling
error over generations

Question 18

what is inbreeding?

Answer 18

mating with someone who shares similar genes with you

Question 19

how does genetic drift happen quickly?

Answer 19

genetic drift happens quickly over a small population

Question 20

what is the bottleneck effect?

Answer 20

original population has equal frequencies but due to some event the population reduces leading to bottle neck effect hence one of the allele is completely gone and the other becomes rare

Question 21

what is the founder’s effect?

Answer 21

what happens when you establish a new population

Question 22

what happens when there is a few founding individuals?

Answer 22

can’t capture all of the diversity in the parent population

Question 23

when is bottleneck effect pronounced?

Answer 23

tiny population

Question 24

what happens for genetic diversity overtime in the founders effect?

Answer 24

• takes really long time to evolve
• old population has more genetic diversity than new

Question 25

what is Stabilising Selection?

Answer 25

reduces variation but does NOT change the mean

Question 26

what is Directional Selection?

Answer 26

changes the mean value towards one extreme

Question 27

what is Disruptive Selection?

Answer 27

favors the two extremes producing two peaks

Question 28

what happens before & after in Stabilising Selection?

Answer 28

before - Medium-sized individuals are favored - Phenotypes favored by natural selection after - Peak gets higher and narrower

Question 29

what happens before & after in Directional Selection?

Answer 29

before - Larger individuals favored after - Peak shifts in one direction

Question 30

what happens before & after in Disruptive Selection?

Answer 30

before - Large and small individuals favored after - Two peaks form

Question 31

what is sexual selection?

Answer 31

- not determined by phenotype's usefulness just whats valued by other sex - one phenotype that might be liked by the other sex more than others

Question 32

what is sexual selection?

Answer 32

- not determined by phenotype's usefulness just what's valued by other sex - one phenotype that might be liked by the other sex more than others

Question 33

what is Frequency-dependent selection?

Answer 33

Selection depends on how rare or how common a phenotype is

Question 34

what does being rare do to you?

Answer 34

increases chances of survival and reproduction but once you succeed you become common and are no longer subjected to that selective advantage

Question 35

what is a cline?

Answer 35

The gradual geographic change in genetic/phenotypic composition is termed a cline

Question 36

what is mutation?

Answer 36

Very slow to act and usually disadvantageous, its role is usually of macroevolutionary proportions

Question 37

what is Migration?

Answer 37

An individual from another population successfully mates (i.e. contributes gametes) to the gene pool

Question 38

what are the advantages of migration?

Answer 38

- brings new alleles - changes proportions of existing alleles - changes population size - makes two populations more similar