Population genetics and natural selection

Question 1

2 reasons why we might need to estimate frequencies of genotypes in a population

Answer 1

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 2

how do we predict genotypes in a population

Answer 2

by using the Hardy-Weinberg equation where:
p = dominant allele frequency
q = recessive allele frequency
p^2+2pq+q^2=1

Question 3

what are the 7 ways an allele frequency can change

Answer 3

1. non random mating
   - assortative mating
   - inbreeding
2. random genetic drift
3. bottle neck effect
4. founder effect
5. Natural selection
6. Gene flow or migration
7. Mutation

Question 4

what is random genetic drift

Answer 4

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

Question 5

what is the bottle neck effect

Answer 5

a drastic reduction in a population’s size due to a sudden event, like a natural disaster or human activity
results in drastic change in allele frequency as one allele can be completely lost

Question 6

what is the founder effect

Answer 6

The founder effect, in genetics, refers to the loss of genetic diversity that occurs when a new population is established by a small group of individuals from a larger population. This small founding population may not be a representative sample of the genetic variation of the original population, leading to differences in allele frequencies and a reduced range of traits in the new population.

Question 7

what are the 3 types of selection

Answer 7

1. disruptive selection
2. directional selection
3. stabilizing selection

Question 8

what is disruptive selection

Answer 8

a type of natural selection where individuals with extreme traits have a higher fitness than those with intermediate traits
- the 2 extremities are picked for and the intermediate is picked against

Question 9

what is directional selection

Answer 9

Directional selection is a type of natural selection where a population evolves toward one extreme of a trait spectrum
- only one of the extreme traits are picked for

Question 10

what is stabilizing selection

Answer 10

a type of natural selection where individuals with intermediate traits or phenotypes have a higher fitness than individuals with extreme traits
- the intermediate trait is picked for and the extremities are picked against

Question 11

what is sexual selection

Answer 11

natural selection arising through preference by one sex for certain characteristics in individuals of the other sex
certain trait is found more attractive than another and is selected for

Question 12

what is frequency dependent selection

Answer 12

the concept that the fitness of a trait or phenotype is influenced by its frequency within a population
- fitness of a genotype is influenced by how rare or common it is

Question 13

what is the spatial disruptive of genetic variation

Answer 13

The spatial distribution of genetic variants is jointly determined by geography, past demographic processes, natural selection, and its interplay with environmental variation

Question 14

what is cline

Answer 14

the gradual geographic change in genetic/phenotype composition