Lesson 5: Population Genetics

Question 1

Population

Answer 1

A population is defined as a localized group of a single species occupying a particular area
—factors affecting population genetics:
1. Immigration and emigration
2. Mutations
3. Genetic drift
4. Non-random mating

Question 2

Immigration and Emigration

Answer 2

-the movement of idv into a population (immigration) introduces new alleles to the population
-the movement of idv out of a population (emigration) removes alleles a population
-the movement of allele is called gene flow

Question 3

Mutations

Answer 3

-if a mutation is inheritable it may introduce new alleles to a population
—the expression of these alleles may be neutral, favorable or unfavorable
—mutations increase variation in the allele frequency of a species
—not likely to cause a change in allele frequency’s unless the mutation provides a selective advantage

Question 4

Genetic drift

Answer 4

-allele frequencies dramatically changed by chance alone
-occurs only in small population
-types of genetic drift include the bottleneck effect and the Founder effect

Question 5

Bottleneck effect

Answer 5

As a result of random chance, certain alleles are overrepresented in a reduced population

Question 6

Bottleneck effect—how it happens

Answer 6

1. A large population is drastically reduced
2. The surviving population is not representative of the gene pool of the original population
3. Genetic Drift occurs as the population’s genetic variation is reduced to that of the surviving population

Question 7

Founder effect

Answer 7

Genetic Drift due to a small group of idvs colonizing a new area
—the effect is often compounded by the selective pressures (natural selection) of the new environment

Question 8

Non-random mating

Answer 8

Many populations do not reproduce randomly. Sexual reproduction is usually selective

types of non-random mating:
1. Assortive mating
2. Sexual selection
3. Inbreeding
4. Artificial selection

Question 9

Assortive mating

Answer 9

-idvs choose partners that have a particular phenotype
-reduces genetic diversity as idvs who do not possess the phenotype do not successfully reproduce

Question 10

Sexual selection

Answer 10

sexual dimorphism is reproduction’s basis. Alleles of the most reproductively adapted species—rather than necessarily the most adapted to the environment are passed on via the display of peculiar female behavioral traits, and mating displays.
ex: peahen chooses peacock with most vibrant colours/feathers (because he looks strong, fast, and can get away)

Question 11

Inbreeding

Answer 11

-mating b/t two closely related idvs
—does not change allele frequency’s but it does result in more homozygous idvs.

ex- self-fertilization in plants

Question 12

Artificial selection

Answer 12

-human selection of particular traits by the selective breeding of idvs
-human action selects the trait
Ex- dogs