Evolution of Populations

Question 1

Define population

Answer 1

Localized group of individuals (a species in an area) capable of interbreeding and producing fertile offspring

Question 2

Two Hardy-Weinberg Equations

Answer 2

p + q = 1 (allele) (B, b)
p^2 + 2pq +q^2 = 1 (individuals) (BB, Bb, bb)

Question 3

List the 5 conditions that a population must satisfy to remain in Hardy-Weinberg equilibrium (non-evolving population)

Answer 3

• No mutations (no genetic change)
• Random mating (no sexual selection)
• No natural selection (no alleles/genotypes selected over other)
• No genetic drift
• No gene flow (no migration) no new allele can come into the population or be lost

Question 4

List the 5 conditions that a population must satisfy in order to be evolving

Answer 4

• Mutation
• Natural Selection
• Genetic Drift
• Gene flow
• Non-random mating (sexual selection)

Question 5

Genetic Drift
Bottleneck effect and founder effect

Answer 5

Allele frequencies fluctuate unpredictably from one generation to the next
(causes allele frequencies to change at random)
Bottleneck effect - population is sharply reduced in size by a natural disaster
Founder effect - small group slits off from the main population to found a colony

Question 6

Gene flow

Answer 6

Non-random movement of genes into or out of a population by migration
Reduces differences between populations over time

Question 7

Population Genetics

Answer 7

Study of how populations change genetically over time

Question 8

Microevolution

Answer 8

Change in allele frequencies in a population over generations

Question 9

Mutations

Answer 9

Changes in the nucleotide sequence of DNA
(only mutations in cells that produce gametes can be passed to offspring and can change the gene pool)

Question 10

Three modes of Natural Selection

Answer 10

• Directional Selection
• Disruptive Selection (diversifying selection)
• Stabilizing Selection

Question 11

Examples of Bottleneck effect

Answer 11

Natural disasters - earthquakes, floods, fires

Question 12

Non-random mating

Answer 12

If individuals (usually females) are choosy in their selection of mates, the gene frequencies may become altered.
- Sexual Selection

Question 13

Directional Selection
examples?

Answer 13

Favors individuals at one end of the phenotypic range
ex. peppered moth (originally white, but dark phenotypes survived), antibiotic resistance, evolution of horse size, more sickle cell genes in areas that are high in malaria, giraffe neck size

Question 14

Disruptive/Diversifying selection
examples?

Answer 14

Favors individuals at both extremes of the phenotypic range (rare)
ex. black-bellied seed crackers in Africa (either large or small beak size)

Question 15

Stabilizing Selection
examples?

Answer 15

Favors intermediate variants and acts against extreme phenotypes
ex. human birth weight, medium height plants, Siberian husky, clutch size in birds