Chapter 21: Microevolution

Question 1

Microevolution

Answer 1

The change in the frequencies of alleles in the gene pool of a population. It changes the population but does not create new species.

Question 2

Population

Answer 2

All individuals of the same species in a common area.

Question 3

Gene pool

Answer 3

All the genes in the population at any given time
Or
The sum of all alleles at all gene loci in all individuals in a population

Question 4

Phenotypic Variation

Answer 4

Differences in appearance or function between individual organisms.

Question 5

Quantitative variation

Answer 5

Variation that is measured on a continuum (such as height in human beings) rather than in discrete units or categories

Question 6

Qualitative variation

Answer 6

Variation that exists in two or more discrete states, with intermediate forms often being absent

Question 7

Genotypic frequencies

Answer 7

The percentage of individuals in a population possessing a particular genotype

Question 8

Allele frequencies

Answer 8

The abundance of one allele relative to others at the same gene locus in individuals of a population.

Question 9

Null model

Answer 9

A conceptual model that predicts what one would see if a particular factor had no effect

Question 10

Sexual selection

Answer 10

A form of natural selection established by male competition for access to females and by the females’ choice of mates.

Question 11

Sexual dimorphism

Answer 11

Differences in the size or appearance of males and females

Question 12

Interbreeding

Answer 12

A special form of nonrandom mating in which genetically related individuals mate with each other

Question 13

Heterozygote advantage

Answer 13

An evolutionary circumstance in which individuals that are heterozygous at a particular locus have higher relative fitness than either homozygote.

Question 14

Frequency-dependent selection

Answer 14

A form of natural selection in which rare phenotypes have a selective advantage simply because they are rare.

Question 15

Neutral variation hypothesis

Answer 15

An evolutionary hypothesis that some variation at gene loci coding for enzymes and other soluble proteins is neither favored nor eliminated by natural selection

Question 16

Selectively neutral

Answer 16

See neutral variation hypothesis

Question 17

Adaptive trait

Answer 17

A genetically based characteristic, preserved by natural selection, that increases an organism’s likelihood of survival or its reproductive output.

Question 18

Adaptation

Answer 18

Characteristic that helps an organism survive longer or reproduce more under a particular set of environmental conditions.