Chapter 13 Natural selection

Question 1

gene pools

Answer 1

-range of genes and all their alleles present in a population

-large pool -> extensive genetic diversity
-small pool -> inbreeding

Question 2

Positive phenotypic selection

Answer 2

Favours heritable trait, so allele frequency increases

Question 3

Negative phenotypic selection

Answer 3

disfavours a heritable trait, so allele frequency will decrease in a population

Question 4

gene flow

Answer 4

-occur in migrants breed
-transfer of alleles that results from emigration and immigration

Question 5

genetic drift

Answer 5

-A change in the gene pool of a population as a result of chance
-Usually occurs in small populations

Question 6

Genetic drift: Founder effect

Answer 6

Occurs when a small group of individuals breaks off from a large population to establish a colony

Question 7

Genetic drift: Bottleneck effect

Answer 7

-When size of a population is severely reduced
-Events like natural disasters

Question 8

Selection pressure

Answer 8

Environmental factor that affects survival and reproductive success of an individual based on their particular phenotype

Question 9

Types of phenotypic selection

Answer 9

1. Stabilising
2. Directional
3. Disruptive

Question 10

Stabilising

Answer 10

-Form of selection that tends to advantage organisms similar to parents
-Usually occurs when environment is stable and selects against extremes of phenotype

Question 11

Directional

Answer 11

-Form of selection that selects against one or the two extremes and leads to a change in a trait over time

Question 12

disruptive

Answer 12

-Form of selection that operates in favour of extremes and against intermediate forms

Question 13

Viability

Answer 13

Survival

Question 14

Fecundity

Answer 14

-Reproduction
-Measure of fertility, capacity to reproduce