exam 3: evolution at multiple loci

Question 1

What two major concepts in biology were unified in the middle of the twentieth century?

Answer 1

natural selection & medelian genetics

Question 2

the rediscovery of Mendelian inheritance caused increased scrutiny of Charles Darwin’s
theory of natural selection because of an apparent conflict in the two concepts. This conflict was
based on the observation that Darwin focused on continuous traits, while Mendelian genetics
deals with

Answer 2

discrete characters

Question 3

The observation of an offspring phenotype outside of the range of parental phenotypes is most
likely due to

Answer 3

latent variation

Question 4

Selection can generate novel phenotypes by

Answer 4

increasing the probability of novel allele combinations

Question 5

a halotype is

Answer 5

a set of alleles at different loci along a chromosome.

Question 6

Consider two loci located close together on a single chromosome. These loci

Answer 6

are physically linked

Question 7

The statistical association of alleles at different loci is referred to as

Answer 7

linkage disequilibrium

Question 8

Which of the following is most likely to break up linkage disequilibrium?

Answer 8

recombination

Question 9

Which of the following processes that can create linkage disequilibrium is illustrated in the
figure?

Answer 9

migration

Question 10

. What is one reason why antibiotic resistance does not always disappear as quickly as one
might expect after large-scale antibiotic use is ended?

Answer 10

compensatory mutationd arise at other loci in resistant bacteria strains, which eliminate fitness costs associated with the resistant phenotype

Question 11

. In the figure, a new beneficial allele, B, arises on a chromosome containing the ordered loci
A, B, C, D, and E, depicted in the top panel. After reproduction, those chromosomes possessing
the B allele increase in frequency. Over time, recombination breaks up the association of the B
allele with the A, C, D, and E alleles. Assuming that the five loci are spaced evenly along the
chromosome, the first pair of allele combinations to be broken up will most likely be

Answer 11

B & E

Question 12

Which of the following occurs when there is so much Mendelian variation within a
population that all of the possible genotypes cannot be represented in any given generation

Answer 12

latent variation

Question 13

In the figure, the population indicated by the dots

Answer 13

has high fitness

Question 14

Genotypic adaptive landscapes may better represent true adaptive landscapes than phenotypic
adaptive landscapes when

Answer 14

single mutations can have a large effect on the phenotype

Question 15

in quantitative genetic terms, a phenotypic value can be expressed as

Answer 15

genotypic value and environmental deviation

Question 16

The figure demonstrates Hardy–Weinberg frequencies at two loci. Which term represents the
expected offspring haplotype frequencies for a cross between parents with aB and aB gametes?

Answer 16

u^2

Question 17

Narrow-sense heritability is defined as the ________ genetic variation divided by the
________ variation.

Answer 17

additive genetic variance, phenotypic

Question 18

n the figure depicting the heritability of migratory timing in the blackcap warbler, what does
the straight line indicate?

Answer 18

the narrow-sense heritability

Question 19

A researcher tracks the escape behavior of a population of squirrels on campus across two
generations. When she plots the escape behavior of the offspring generation against the parental
behavior, she notes that the offspring’s behavior exactly matches the parental behavior.
Nonetheless, the narrow-sense heritability equals zero. How can the heritability equal zero in this
example?

Answer 19

-the additive genetic variance equals zero
-all the escape behavior alleles are fixed in the pop

Question 20

The phenotypic variation created by random chance events during the process of an
organism’s development is called

Answer 20

developmental noise

Question 21

In a population of dragonflies, wing structure is determined by two loci (A, B), each with two
alleles (A and a, B and b). Abnormal wings are produced in aa individuals unless they possess at
least one B allele. This is an example of what evolutionary phenomenon?

Answer 21

epistasis

Question 22

Which of the following does NOT represent a way in which genotype and phenotype can
interact?

Answer 22

physical linkage

Question 23

An individual mapped within an adaptive landscape as a point located in a fitness valley
would be characterized as having

Answer 23

low fitness

Question 24

Which of the following reflects the degree to which offspring resemble their parents in a
population?

Answer 24

narrow-sense heritability

Question 25

When the alleles at two or more loci interact in nonadditive ways, we refer to this as

Answer 25

epistasis

Question 26

If we are interested in the A, B, and C loci of a diploid organism, which of the following
would be a possible haplotype?

Answer 26

ABc

Question 27

Which of the following processes causes a neutral allele to increase in frequency because it is
linked to an allele under selection?

Answer 27

genetic hitchhiking