Chapter 6 - Drift and Selection

Question 1

The specific location of a gene or piece of DNA sequence on a chromosome.

Answer 1

Genetic Locus

Question 2

The study of the distribution of alleles within populations and the mechanisms that can cause allele frequencies to change over time.

Answer 2

Population Genetics

Question 3

A mathematical statement that has been proven based on previously established.

Answer 3

Theorem

Question 4

An allele becomes fixed in a population when all of the alternative alleles have disappeared. No genetic variation exists at a fixed locus within a population, because all individuals are genetically identical at that locus.

Answer 4

Fixed Allele

Question 5

Events in which the number of individuals in a population is reduced drastically. Even is this dip in numbers is temporary, it can have lasting effects on the genetic variation of a population

Answer 5

Genetic Bottleneck

Question 6

A type of genetic drift describing the loss of allele variation that accompanies founding of a new population from a very small number of individuals. This effect can cause the new population to differ considerably from the source population.

Answer 6

Founder Effect

Question 7

The success of an organism at surviving and reproducing, and thus contributing offspring to future generations.

Answer 7

Fitness

Question 8

The success of the genotype at producing new individuals (its fitness) standardized by the success of other genotypes in the population (for example, divided by the average fitness of the population)

Answer 8

Relative Fitness

Question 9

the difference between the average fitness of individuals bearing the allele and the average fitness of the population as a whole.

Answer 9

Average Excess of Fitness

Question 10

The condition when a mutation in a single gene affects the expression of many different phenotypic traits.

Answer 10

Pleiotropy

Question 11

Selection that decreases the frequency of alleles within a population

Answer 11

Negative Selection

Question 12

Selection that increases the frequency of alleles within a population.

Answer 12

Positive Selection

Question 13

Occurs when the effects of an allele at one genetic locus are modified by alleles at one or more other loci.

Answer 13

Epistasis

Question 14

An allele that yields twice the phenotypic effect when two copies are present at a given locus than when only a single copy is present

Answer 14

Additive Allele

Question 15

Rare genotypes have higher fitness than common genotypes. this process can maintain genetic variation within populations.

Answer 15

Negative Frequency-Dependent Selection

Question 16

Selection that favors more than one allele. It acts to maintain genetic diversity in a population by keeping alleles at frequencies higher than would be expected by chance or mutation alone.

Answer 16

Balancing Selection

Question 17

The probability that the two alleles at any locus in an individual will be identical by descent.

Answer 17

Inbreeding Coefficient

Question 18

A reduction in the average fitness of inbred individuals relative to that of outbred individuals. it arises because rare, recessive alleles become expressed in a homozygous state where they can detrimentally affect the performance of individuals.

Answer 18

Inbreeding Depression