Chapter 6

Question 1

Population genetics

Answer 1

Study of allele frequencies and distribution

Question 2

Hardy-Weinberg Theorem

Answer 2

Without outside forces alleles in a population will remain static; no emigration, infinitely large population, everyone has equal opportunity to survive

Question 3

Allele frequency

Answer 3

Frequency of one letter in genotype

Question 4

Genotype frequency

Answer 4

Frequency of a gene (both alleles)

Question 5

Selection

Answer 5

Environmental factors are unfavorable for some alleles

Question 6

Gene flow (migration)

Answer 6

Individuals with new allele enter population; new allele is more common

Question 7

Loci

Answer 7

Specific location of a gene or piece of DNA sequence in a chromosome

Question 8

Fixation of alleles

Answer 8

All other alternative alleles have disappeared; individuals only carry that one allele

Question 9

Genetic bottlenecks

Answer 9

Number of individuals in a population are reduced drastically, changing genetic variation

Question 10

Founder effect

Answer 10

Genetic drift describing loss of allelic variation that comes with founding of new population from a small number of individuals

Question 11

Fitness

Answer 11

Survival and reproduction

Question 12

Average excess of fitness

Answer 12

Difference between the average fitness of individuals bearing an allele and the population as a whole

Question 13

Pleitropy

Answer 13

Mutation in a single gene affects multiple phenotypes

Question 14

Negative selection

Answer 14

Decreases frequency of alleles within a population

Question 15

Positive selection

Answer 15

Increases frequency of alleles within a population

Question 16

Epistasis

Answer 16

Effects of an allele at one genetic locus are modified by alleles at other loci

Question 17

Additive allele

Answer 17

An allele that yields twice the phenotypic effect when two copies are present

Question 18

Dominance

Answer 18

One allele determines phenotype when present; overshadows other allele completely

Question 19

Mutation-selection balance

Answer 19

Negative mutations are selected against, keeping allele frequencies relatively stable

Question 20

Frequency dependent selection

Answer 20

Rare genotypes have higher fitness than common ones

Question 21

Balancing selection

Answer 21

Selection that favors more than one allele; maintains genetic diversity

Question 22

Inbreeding coefficient

Answer 22

Probability that the two alleles at any locus will be identical by descent

Question 23

Inbreeding depression

Answer 23

Reduction in average fitness of inbred individuals vs. outbred individuals