Chapter 19 Vocab

Question 1

Population Genetics

Answer 1

The study of genetic variability within a population and of the evolutionary forces that act on it.

Question 2

Gene pool

Answer 2

Includes all of a polulation’s alleles for all the loci present.

Question 3

Genotype frequency

Answer 3

The proportion of a particular genotype in a population, expressed as a decimal fraction.

Question 4

Hardy-Weinberg Principle

Answer 4

Frequencies of alleles and genotypes in a population do not change from generation to generation unless influenced by outside factors.

Question 5

Genetic equilibrium

Answer 5

A population with no net change in allele or genotype frequencies over time.

Question 6

Microevolution

Answer 6

Refers to relatively small generation-to-generation changes in allele or genotype frequencies within a population.

Question 7

Inbreeding

Answer 7

Mating of individuals who are more closely related than if they had been chosen at random from the population.

Question 8

Sexual selection

Answer 8

Form of nonrandom mating that favors traits that increase the chanced of reproduction.

Question 9

Sexual dimorphism

Answer 9

Evolution of significant differences between males and females of a species.

Question 10

Mutation

Answer 10

Any change in the nucleotide sequences of DNA.
Ultimate source of genetic variation in a population.
Only mutations in reproductive cells are inherited.

Question 11

Genetic Drift

Answer 11

Random evolutionary changes in small breeding populations results in changes in allele frequencies in a population.
- Decreases genetic variation in a population, increases genetic differences among different populations.

Question 12

Population bottleneck

Answer 12

Occasionally a population may rapidly and severely decrease due to disease, exploitation, or sudden environmental change.
- Can occur in small population of survivors.

Question 13

Founder Effect

Answer 13

Genetic drift that results when a few individuals from a large population found a new colony.

Question 14

Gene Flow

Answer 14

Migration of breeding individuals between populations, with a corresponding movement of alleles, increasing genetic variability in the recipient population.
- Can counteract the effects of natural selection and genetic drift.

Question 15

Stabilizing selection

Answer 15

Preserves average phenotype.
Selects against phenotypic extremes, favors individuals with average phenotypes.
Narrows the bell curve

Question 16

Directional selection

Answer 16

Favors individuals that vary in one direction
When an environment changes, phenotypes at one extreme of the normal distribution are favored.

Question 17

Disruptive selection

Answer 17

favors individuals that very in both directions from the mean.