exam 3: evolution at multiple loci Flashcards
What two major concepts in biology were unified in the middle of the twentieth century?
natural selection & medelian genetics
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
discrete characters
The observation of an offspring phenotype outside of the range of parental phenotypes is most
likely due to
latent variation
Selection can generate novel phenotypes by
increasing the probability of novel allele combinations
a halotype is
a set of alleles at different loci along a chromosome.
Consider two loci located close together on a single chromosome. These loci
are physically linked
The statistical association of alleles at different loci is referred to as
linkage disequilibrium
Which of the following is most likely to break up linkage disequilibrium?
recombination
Which of the following processes that can create linkage disequilibrium is illustrated in the
figure?
migration
. What is one reason why antibiotic resistance does not always disappear as quickly as one
might expect after large-scale antibiotic use is ended?
compensatory mutationd arise at other loci in resistant bacteria strains, which eliminate fitness costs associated with the resistant phenotype
. 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
B & E
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
latent variation
In the figure, the population indicated by the dots
has high fitness
Genotypic adaptive landscapes may better represent true adaptive landscapes than phenotypic
adaptive landscapes when
single mutations can have a large effect on the phenotype
in quantitative genetic terms, a phenotypic value can be expressed as
genotypic value and environmental deviation
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?
u^2
Narrow-sense heritability is defined as the ________ genetic variation divided by the
________ variation.
additive genetic variance, phenotypic
n the figure depicting the heritability of migratory timing in the blackcap warbler, what does
the straight line indicate?
the narrow-sense heritability
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?
-the additive genetic variance equals zero
-all the escape behavior alleles are fixed in the pop
The phenotypic variation created by random chance events during the process of an
organism’s development is called
developmental noise
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?
epistasis
Which of the following does NOT represent a way in which genotype and phenotype can
interact?
physical linkage
An individual mapped within an adaptive landscape as a point located in a fitness valley
would be characterized as having
low fitness
Which of the following reflects the degree to which offspring resemble their parents in a
population?
narrow-sense heritability
When the alleles at two or more loci interact in nonadditive ways, we refer to this as
epistasis
If we are interested in the A, B, and C loci of a diploid organism, which of the following
would be a possible haplotype?
ABc
Which of the following processes causes a neutral allele to increase in frequency because it is
linked to an allele under selection?
genetic hitchhiking
