Evolutionary Processes

Question 1

what is the definition of evolution?

Answer 1

Change in the genetic composition of a population

Question 2

what does natural selection do?

Answer 2

Increases frequency of alleles that contribute to reproductive success in a particular environment
Can reduce genetic variation

Question 3

what is gene flow?

Answer 3

Occurs when individuals leave one population, join another, and breed
Arriving individuals can introduce new alleles into the population

Question 4

Assumptions of the Hardy-Weinberg Principle

Answer 4

1. No natural selection – All parents contribute equally to the gene pool
2. No genetic drift – No changes in allele frequencies due to chance *assume a large population
3. No gene flow – No new alleles added to the population (no immigration (no emigration))
4. No mutation – No creation of new alleles
5. Random mating – Individuals do not choose mates; gametes combine randomly

Question 5

what evolutionary processes can change allele frequencies over time?

Answer 5

Natural selection, Drift, Gene flow, Mutation

Question 6

Natural selection results in changes to _____ _______

Answer 6

Allele Frequencies

Question 7

Genetic variation is important because…

Answer 7

Selection can only occur if heritable variation exists

Question 8

DIRECTIONAL SELECTION
give a definition and what is does

Answer 8

DIRECTIONAL SELECTION favours on extreme of the phenotype distribution.
-changing the average trait value in the population ONE direction.
-decreases genetic diversity

Question 9

The decline in frequency of disadvantageous alleles is called?

Answer 9

purifying selection

Question 10

Directional selection is often constrained by…?

Answer 10

Fitness trade-offs

Question 11

give the definition of STABILIZING SELECTION

Answer 11

Stabilizing selection Reduces frequency of both extremes of the phenotype distribution

Question 12

give the definition of DISRUPTIVE SELECTION

Answer 12

Disruptive selection Intermediate phenotypes are selected against and extreme phenotypes are favoured

Question 13

give the definition of BALANCING SELECTION

Answer 13

Balancing selection occurs when no single allele has a distinct advantage

Question 14

define Genetic drift

Answer 14

Changes in allele frequencies due to chance – causes frequencies to drift up and down randomly over time Sampling error – selection of non-representative sample of population by chance

Question 15

Define mutation

Answer 15

Random errors that can occur when DNA is copied

Question 16

Mutation ________ genetic diversity by creating new alleles

Answer 16

Mutation RESTORES genetic diversity by creating new alleles