Evolutionary bio final exam study guide

Which statement(s) is (are) true? (0.1)
-Natural selection acts on populations, not on individuals.
-Mutations are the raw material for natural selection.
-Evolutionary change occurs at the level of the population.
-Developmental change is a population-level process.
-Species are simply those organisms that share similar phenotypes.

-Mutations are the raw material for natural selection.
-Evolutionary change occurs at the level of the population.

Many types of antibiotics that were highly effective a few decades ago are not nearly as effective in the present. Why might this be the case? (0.1)

Bacteria have evolved resistance to antibiotics, driven by natural selection.

In the 1930s and 1940s the modern evolutionary synthesis occurred. Which of these was not a major outcome of the evolutionary synthesis? (0.1)

-The integration of genomics with evolutionary biology
-Widespread acceptance of the inheritance of acquired characteristics

What are the major themes of On the Origin of Species? (0.1)

- descent with modification
- a variational theory of change, through natural selection

Biological evolution is defined as (0.1)

change in the properties of groups of organisms over the course of generations.

Which of these did not influence Darwin's development of his theory of evolution by natural selection? (0.1)

-Knowledge of inheritance, as discovered by Gregor Mendel.
-Correspondence with Alfred Russel Wallace over many years after the voyage of the H.M.S. Beagle.

Natural selection is only one of several possible mechanisms of evolution. Another mechanism is (0.1)

speciation and genetic drift

What were the outcomes of Wallace's 1858 letter to Darwin, which included Wallace's ideas of natural selection? (0.1)

-Darwin was prompted to debate Wallace about the conflicts in their ideas
-Darwin arranged to present his research on natural selection alongside Wallace's at a meeting of the Royal Society

Why would evolutionary biology be one of the best paradigms in which to study the spread of viruses like COVID-19 into new populations and species?(0.1)

Evolutionary biologists work on understanding how populations (the viruses) adapt to new environments (the hosts)

Which of the following are among the principles of evolution? (0.1)

-Heritable variation can be maintained because of the particulate nature of genes
-Natural selection need not be strong in order for substantial evolutionary change to take place over the long term

In the early twentieth century, many geneticists were at odds with evolutionary biologists. Why? (0.1)

-Geneticists observed mutations with large effects, while Darwin suggested evolution occurs via small changes
-Darwin did not understand how genetic inheritance works when he formulated his theory

Which of the following are not among Darwin's theories? (0.1)
-Evolution (change over time)
-Common descent
-Change via saltations (extreme, sudden changes in an organism's traits)
-Population change
-Inheritance via transmission of genetic code from parents to offspring

-Change via saltations (extreme, sudden changes in an organism's traits)
-Inheritance via transmission of genetic code from parents to offspring

Uniformitarianism allows evolutionary biology to be an experimental science. Which of the following are examples of uniformitarianism?
-Members of a natural population of finches that deviate from the norm are identified as monstrosities.
-Observations of erosion on a streambank demonstrate how a canyon was formed
-When choosing between competing hypotheses without other evidence, the simplest explanation is usually the most likely
-Experiments with decomposing animal corpses are used to help explain how fossils form
-The development of a fish embryo shows how vertebrates evolved from simpler invertebrates (0.1)

-Observations of erosion on a streambank demonstrate how a canyon was formed
-Experiments with decomposing animal corpses are used to help explain how fossils form

Which of the following is the most important assumption when estimating the time of divergence between two lineages using a molecular clock? (0.2)

The number of nucleotide substitutions observed is actually the number that has occurred.

Homologous characters are defined as (0.2)

Traits shared between species because of inheritance from their common ancestor

Consider the phylogeny below, depicting relationships between five species and whether they carry one of two different states for a particular homologous trait, A or B: Which branch of the phylogeny is the most likely place at which the ancestral state A evolved to become the derived state, B? (0.2)
Refer to the pdf file that I sent q16

The branch between node "b" and node "d"

Which of the five nodes labeled with lowercase letters are the most recent shared ancestor of Species 3 and Species 2? (0.2)
Refer to the pdf file that I sent q17

node b

Consider the phylogeny below, depicting relationships between five species and whether they carry one of two different states for a particular homologous trait, A or B: If the character state at the node labeled "a" is A, which of the following would be true? (0.2)
Refer to the pdf file that I sent q 18

Character state B would be a synapomorphy of the clade made up of Species 3 and Species 4

Which of the following is/are example(s) of homologous characters?
-some flies have bright yellow coloring like that of wasps, which provides a false warning.
-birds and turtles both have blood cells that carry oxygen bound in hemoglobin molecules
-crocodiles and humans both have forelimbs with five digits
-parrotfish and parrots (the birds) both have beaklike mouths
-the aquatic larval stage was lost in a lineage of salamanders but was later regained (0.2)

-birds and turtles both have blood cells that carry oxygen bound in hemoglobin molecules
-crocodiles and humans both have forelimbs with five digits
-parrotfish and parrots (the birds) both have beaklike mouths

Consider the phylogeny below, depicting relationships between five species. Which of the five nodes labeled with lowercase letters is the most recent shared ancestor of Species 3 and Species 2? (0.2)
Refer to the pdf file q20

Node b

Consider the phylogeny below, depicting relationships between five species and whether they carry one of two different states for a particular homologous trait, A or B. If the character state at the node labeled "a" is A, which of the following would be true? (0.2)
-Character state B would be the derived state
-Character state A would be the ancestral state
-Character state B would be the ancestral state
-Species 3 and Species 4 probably evolved character state B independently
-Character state B would be a synapomorphy of the clade made up of Species 3 and Species 4

-Character state B would be the derived state
-Character state A would be the ancestral state
-Character state B would be a synapomorphy of the clade made up of Species 3 and Species 4

A monophyletic group (also called a clade) is defined as (0.2)

The set of species derived from one common ancestor

Convergent evolution is a form of (0.2)

Homoplasy

Consider the phylogeny below, depicting relationships between five species. What term would describe a group including only Species 1, Species 2, and Species 4? (0.2)
Refer to the pdf q24

polyphyletic

A synapomorphy is defined as (0.2)

A derived trait shared by all taxa in a clade

Consider the phylogeny below, depicting relationships between five species and whether they carry one of two different states for a particular homologous trait, A or B. What is the most likely version of the character carried by the most recent ancestor of Species 3 and Species 4? (That is, what is the most likely character state at the node labeled "d"?) (0.2)
refer to the pdf q26

B

Consider a population of individuals that carry either a Q or a q allele at a particular locus. Across the population, 10 individuals carry QQ genotypes, 70 carry Qq genotypes, and 20 carry qq genotypes.
What is the expected number of individuals carrying the QQ genotype if the population is in Hardy-Weinberg equilibrium? (1.1)

pQ = (2 x 10 + 70)/200 = 90/200 = 0.45
PQQ = pQ x pQ = 0.45 x 0.45 = 0.2025
0.20 x 100 = 20 individuals carrying QQ

QqIn the same population as above, what is the expected number of individuals carrying the Qq genotype if the population is in Hardy-Weinberg equilibrium? (1.1)

pq = (2 x 20 + 70)/200 = 110/200 = 0.55
PQq = 2 x pQ x pq = 0.45 x 0.55 = 0.495
0.50 x 100 = 50 individuals carrying Qq

In the same population as above, what is the expected number of individuals carrying the qq genotype if the population is in Hardy-Weinberg equilibrium? (1.1)

Pqq = pq x pq = 0.55 x 0.55 = 0.3025
0.30 x 100 = 30 individuals carrying qq

Are the observed numbers of individuals with each of the three diploid genotypes what you expect if the population is in HWE? (1.1)

You should see that the expected genotype numbers you estimated do not match the original observed genotype numbers, which suggests the population is NOT in Hardy-Weinberg equilibrium.

A population of 1000 diploid individuals has a locus with alleles C and c. Across the whole population, the A allele is at a frequency of 0.6. If the population is in Hardy-Weinberg equilibrium, how many individuals would you expect to be homozygous for the c allele at this locus? (1.1)

160

A population of 1000 diploid organisms has alleles B and b at a single locus. There are 770 individuals carrying the BB genotype. If the population is in Hardy-Weinberg equilibrium, how many individuals would you expect to be carrying the bb genotype? (1.1)

15

A population of 500 diploid individuals carry the alleles T and t at a particular genetic locus. If 370 individuals are homozygous for the T allele, and the population is in Hardy-Weinberg equilibrium, what would you expect the frequency of the T allele to be in the population overall? (1.1)

0.86

A population of 1000 diploid individuals has a locus with alleles A and a. Across the whole population, the A allele is at a frequency of 0.33. If the population is in Hardy-Weinberg equilibrium, how many individuals would you expect to be heterozygous at this locus? (1.1)

221

What is a position or region in an organism's genetic sequence? (1.1)

locus

What are different variations of the genetic sequence at that position or region called? (1.1)

alleles

What is the total set of variations carried by an individual? (1.1)

genotype

Refer to this DNA codon table. Which pair(s) of sequences represent synonymous mutation(s)?
- TGA to TGG
-AAT to AAC
-GCT to GCA
-TTT to CTT
-GGA to CGA (1.1)
Please refer to the pdf I sent q38

-AAT to AAC
-GCT to GCA

Nonrandom associations between alleles at different loci are referred to by which term? (1.1)
-Heterozygosity
-Linkage disequilibrium
-Panmictic
-Inbreeding depression
-Linkage equilibrium

Linkage disequilibrium

A population of 1000 diploid organisms has alleles B and b at a single locus. There are 430 individuals carrying the BB genotype. If the population is in Hardy-Weinberg equilibrium, how many individuals would you expect to be carrying the bb genotype? (1.1)

119

Phenotypic differences that are not based on DNA sequence differences (for example, DNA methylation) can be passed from parent to offspring. This phenomenon could be called (1.1)

epigenetic inheritance and maternal effects.

Individuals in a population of diploid organisms either an A allele or a T allele at a particular genetic locus. Which of the following are possible genotypes you might find in this population? (1.1)

TT, AA, AT

The weight-bearing capacity of the bones in your lower leg is probably not an exaptation because ... (1.1)

human lower leg bones evolved from bones in the lower legs of earlier vertebrates

Which of the following effects of human activities on natural populations are probably not examples of adaptive evolution?
-Earlier reproduction in fish species that are harvested based on size
-Earlier flowering dates by plant species in regions where climate change has led to shorter winter
-Reductions in the population sizes of many wild mammal and bird species
-The evolution of antibiotic resistance in disease-causing bacteria
-Reduced genetic diversity in Santa Monica mountain lion populations cut off from other natural areas by highways and development (1.1)

-Reductions in the population sizes of many wild mammal and bird species
-Reduced genetic diversity in Santa Monica mountain lion populations cut off from other natural areas by highways and development

In a particular population of western bluebirds, only about 14 out of 100 chicks survive to mate and reproduce. If the average adult bluebird has 13 chicks over its life, what is the expected fitness of birds in this population? (1.1)

1.82

A particular locus in the genome might have multiple (1.1)

Alleles and Variants

When we say that mutation is random, we mean that (1.1)

-We cannot predict which gene copy will undergo a mutation, and environments do not induce adaptive mutations
-The chance that a mutation occurs is not influenced by whether or not that mutation would benefit the organism
carrying it

A population of 1000 diploid organisms has alleles B and b at a single locus. There are 630 individuals carrying the BB genotype. If the population is in Hardy-Weinberg equilibrium, how many individuals would you expect to be carrying the bb genotype? (1.1)

44.1

Humans have 23 chromosome pairs. Chimpanzees have 24. Without knowing any other information, what kinds of mutation could have caused this difference? (1.1)

Fusions and Fissions

In the figure, the star represents a recent mutation at a gene locus. The letters represent other loci. Which other locus is least likely to be in linkage disequilibrium with the mutation (all else being equal; assume a sexually reproducing organism)? (1.1)

A

Select the terms that could correctly fill in both of the blanks in this statement: A phenotype is any _________; a genotype is the set of one or more ________ that may contribute to creating the phenotype (1.1)

Visible trait; alleles
and
Measurable trait; genetic variants

The weight-bearing capacity of the bones in your lower leg is probably not an exaptation because (1.2)

human lower leg bones evolved from bones in the lower legs of earlier vertebrates.

Which of the following are components of a biological entity's fitness? (1.2)
-its coloration
-its running speed
-its probability of survival
-its expected number of offspring
-its physiological condition

-its probability of survival
-its expected number of offspring

What is the unit of selection that best describes the growth and spread of a cell line carrying a mutation that makes it cancerous within the body of a single individual? (1.2)

The cancer cell line that spreads at the expense of other cells in the body

The light-sensitive rod and cone cells lining the retina in a vertebrate eye are probably not an exaptation because (1.2)

ancestral forms of the eye include clusters of light-sensitive cells.

Which of the following factors can natural selection address? (1.2)
-The reproductive output of individuals within a species
-Traits that will be useful many generations in the future
-Traits that are useful for survival and reproduction in the current generation
-Behaviors that align with human morality
-Traits that improve individuals' ability to hide from predators

-The reproductive output of individuals within a species
-Traits that are useful for survival and reproduction in the current generation
-Traits that improve individuals' ability to hide from predators

Which trait(s) can be thought of as an exaptation for the corresponding function? (1.2)

Heron's wings → blocking the glare of reflected sunlight

Species selection occurs when a trait is correlated with changes in the rates of what processes? (1.2)

-species formation
-species extinction

The light-sensitive rod and cone cells lining the retina in a vertebrate eye are probably not an exaptation
because (1.2)

Ancestral forms of the eye include clusters of light-sensitive cells

In a particular population of western bluebirds, only about 6 out of 100 chicks survive to mate and
reproduce. If the average adult bluebird has 19 chicks over the course of its life, what is the expected fitness
of birds in this population? (1.2)

0.06 x 19 = 1.14
0.06 x 19 = 1.14
-Traits that improve individuals' ability to hide from predators
-Traits that are useful for survival and reproduction in the current generation

Which of the following effects of human activities on natural populations are probably not examples of adaptive evolution? (1.2)
-Reduced genetic diversity in Santa Monica mountain lion populations cut off from other natural areas by
highways and development
-Reductions in the population sizes of many wild mammal and bird species
-Earlier reproduction in fish species that are harvested based on size
-The evolution of antibiotic resistance in disease-causing bacteria
-Earlier flowering dates by plant species in regions where climate change has led to shorter winters

-Reduced genetic diversity in Santa Monica mountain lion populations cut off from other natural areas by
highways and development
-Reductions in the population sizes of many wild mammal and bird species

Species selection occurs when there is a correlation between some trait and the rates of two processes:_______ and _______. (1.2)

speciation and extinction

Which of these conditions would be likely to cause adaptation? (1.2) (can someone make sure that this is the right answer?)

A genetically uniform population living in an environment that changes each generation

An individual organism's fitness is a combination of its _____ and _____. (1.2)

Probability of survival and reproductive success

Alarm calls by ground squirrels alert other ground squirrels to danger, but they also draw attention to the
caller and expose it to increased risk of predation. Such altruistic behavior is best explained by the
phenomenon of (1.2)

Kin selection

Which of these traits cannot be described as an adaptation? (1.2)
-A trait that does not change the probability of survival or reproduction, like the color of an egg's yolk
-A trait that promotes reproduction but does not contribute to survival, like the display behaviors hummingbirds
use to attract mates
-A behavior, like social interactions with other members of the same species, that has a genetic basis but does not involve particular morphological features
-A trait whose organization or structure is suited to the function it performs, like a butterfly's long, extendable
tongue

-A trait that does not change the probability of survival or reproduction, like the color of an egg's yolk

Which statement(s) about natural selection is (are) true? (1.3)
-It is the same as evolution.
-It always results in reduced genetic variation.
-It can operate only if phenotypic differences are heritable.
-It acts directly on genotypes.
-It is the only cause of changes in allele frequencies within populations.
-It only affects phenotypes that are related to fitness

-It can operate only if phenotypic differences are heritable.
-It only affects phenotypes that are related to fitness.

An allele B is currently at a population frequency of 0.62. The B allele increases fitness, creating a selection coefficient equal to 0.09. How much would you expect the frequency of the B allele to change in one generation of natural selection? (1.3)

0.09*0.62*(1-0.62)= 0.0212

What observations about industrial melanism in the peppered moth, Biston betularia, helped convince researchers that the intensity of natural selection can be very strong? (1.3)

-The dark-colored morph increased in frequency very rapidly in multiple populations after the environment changed.
-The dark-colored morph rapidly decreased in frequency when soot pollution decreased.

If a population is evolving only in response to natural selection, the rate at which an allele's frequency in the population will change is dependent on which of the following factors? (1.3)
-Size of the population
-The selection coefficient acting on the allele
-The level of genetic variation at the locus carrying the allele
-Mean fitness of the population
-The traits affected by the allele in question
-The strength of linkage between the allele and other loci under selection

-The selection coefficient acting on the allele
-The level of genetic variation at the locus carrying the allele
-The strength of linkage between the allele and other loci under selection

At a particular locus converts an allele t to a less-fit allele T at a rate of 0.019 per generation. How strong must the selection coefficient against the T allele be to maintain that allele at a frequency no greater than 0.455 at mutation-selection equilibrium? (1.3)

0.019/0.455=0.0418

Human sex ratios are close to equal because if one sex becomes rare, it will be at a fitness advantage and increase in frequency in the population until equilibrium at 50:50 is regained. This is an example of (1.3)

Negative frequency-dependent selection

At a particular locus converts an allele t to a less-fit allele T at a rate of 0.019 per generation. How strong must the selection coefficient against the T allele be to maintain that allele at a frequency no greater than 0.23 at mutation-selection equilibrium? (1.3)

0.019/0.23=0.0826

What pattern(s) would you expect to see in DNA sequences close to an allele undergoing a selective sweep, or strong positive selection? (1.3)

-Decreased variation
-High levels of linkage disequilibrium with the selected locus

The colors of individuals in a snail population are determined by a single autosomal locus. A 1 A 1 homozygotes are red, A 1 A 2 heterozygotes are pink, and A 2 A 2 homozygotes are white. Genotypic
fitnesses are as follows: W A 1 A 1 = 0.65; W A 1A2 = 1.0; WA2A2 = 0.45. (1.3)

\-Allele A1 is more common than allele A2
\-Both alleles are maintained in the population

\-The less beneficial allele will decrease frequency

A population carries two alleles at a locus. One allele has a minuscule fitness advantage. Which of the following are likely to happen at this locus if natural selection is the only evolutionary force affecting it? (1.3)

-Eventually the less beneficial allele will be removed by natural selection
-Both alleles will remain in the population for some period of time
-The less beneficial allele will decrease in frequency

Which variable(s) contribute to an organism's fitness? (1.3)

-mating success
-expected reproductive success
-survival

An allele B is currently at a population frequency of 0.38. The B allele increases 11. fitness, creating a selection coefficient equal to 0.02. How much would you expect the frequency of the B allele to change in one generation of natural selection? (1.3)

0.02 x 0.38 x (1 - 0.38) = 0.0047

Which of these factors would make a trait "Mendelian"? (1.4)
-The trait is determined by a single genetic locus
-Different genotypes have continuously varying differences in the trait
-The trait is determined by several different genetic loci
-Different genotypes have visible, categorical differences in the trait

-The trait is determined by a single genetic locus
-Different genotypes have visible, categorical differences in the trait

Genetic correlations may be caused by which of these? (1.4)

-linkage disequilibrium
-structural relationships between correlated traits
-pleiotropy

Which factor(s) would a breeder need to know to predict the change in a trait over a generation of selection? (1.4)

-The difference in the mean trait value of the population before selection and the mean trait value of the individuals the breeder selects
-The relationship between parents' trait values and the traits of their offspring

In a particular population of Joshua trees, the average length of the pistil, the part of the flower that develops into a fruit, is 20mm. The length of the pistil determines how successful a tree is in interacting with a specialized moth that pollinates the trees, such that flowers with longer pistils produce more seeds — the slope of the relationship between pistil length and the number of seeds produced
is 0.31.
If the additive genetic variance for pistil length is 0.57, how much would you expect the average pistil length to change in one generation of selection due to interaction with the pollinating moths? (1.4)

0.31*0.57=0.1767
20+0.1767=20.1767

In correlated selection, selection favors some combination of trait values over others. This could be because (1.4)

-the traits represent a trade-off.
-the traits are functionally related.

Which of these factors would make a trait "quantitative"? (1.4)
-The trait exists as two or three clearly defined "bins"
-The trait is created by a single genetic locus
-The trait is created by the combined effects of many genetic loci
-Differences between individuals are continuous, rather than sharply different

-The trait is created by the combined effects of many genetic loci
-Differences between individuals are continuous, rather than sharply different

Imagine a population of seed-eating finches that vary in the size of their beaks, with the average beak size well suited to cracking the seeds of the plants in the region the birds occupy.
Suppose a portion of the population migrates to a new territory where the dominant plants have smaller seeds that are easier to open, requiring smaller beaks. Disregarding possible effects of genetic drift, what do you expect to happen to the finches' beaks over generations in the new region, and what kind of selection would cause it? (1.4)

Their beaks should become smaller as a result of directional selection.

A population of butterflies with an average proboscis length of 17 mm migrates to a new habitat where their primary food resource are plants with tubular, nectar-producing flowers — and the flower-tubes are long enough that a butterfly must have a proboscis 20 mm long to drink as much nectar as possible. If the slope of the relationship between a butterfly's proboscis length and its fitness in the new habitat is 7.77, what value of additive genetic variance for proboscis length would ensure that the butterflies can adapt to the flowers in the new habitat? (1.4)

20-17=3
3/7.77=0.3861

What is meant by the statement "Evolution may proceed along 'genetic lines of least resistance'''?

-Correlations among traits may mean fitness increases less rapidly, because traits can evolve only along the
greatest axis of variation
-Characters with little genetic variation will constrain the rate of adaptation

Quantitative trait locus (QTL) mapping and genome-wide association studies (GWAS) are

-Based on correlations, or "associations" between genotypes and trait measurements
-Methods for finding genetic loci that may play a role in a trait of interest

Some crop and livestock species have continued to respond to selection for greater values of desirable traits
(like body size or oil production) for many generations of selective breeding, even as the population's trait value grows far beyond the range of variation seen before selective breeding began. What are possible
reasons for this observation? (1.4)

-Hidden variation revealed by recombination
-Mutation adding new variation as selection removes it

Which pair(s) of traits are more likely to be genetically correlated? (1.4)

-Two traits that are in linkage disequilibrium with each other
-Two morphological traits that must "fit" or "work" together
-A morphological trait that works best with a specific behavioral trait
-Two traits that are affected pleiotropically by a single locus

Which of these bits of genetic material would be expected to be under relatively strong selective constraint? (1.5)

-A nucleotide found at the first position of a codon
-An exon that codes for the active site of an enzyme

Which of these conditions should make a species' effective population size, Ne, closer to the census population size? (1.5)

-The population has remained the same size for many generations.
-Individuals reach sexual maturity quickly, and generations are relatively short.
-There are few matings between full and half-siblings.

How large must the effective population size be so that a selection coefficient of 0.007 will probably overcome genetic drift? (1.5)

1/0.007=142.86

Suppose you compare a region of DNA sequences in two closely related species. You find that, within one gene, the number of nonsynonymous differences between the two species is much greater than the number of synonymous substitutions.
Which of the following can you conclude? (1.5)

-The two species differ in the structure of the protein coded for by this gene.
-The protein coded for by this gene has changed since the divergence of the two species from their common ancestor.
-Changes to the protein coded for by the gene have occurred faster than can be explained by mutation and random genetic drift.

The Congo River formed about 1.5 million years ago and has acted as a barrier, preventing interbreeding by chimpanzees (Pan troglodytes) and bonobos (Pan paniscus). If these two ape species have a mutation rate of 1.2 × 10 -5 (1.2 mutations per 100,000 years), how many mutational differences that we would expect to find between them today? (1.5)

1,500,000* 1.2 × 10 -5*2=36

Which of these patterns could be caused by natural selection or genetic drift? (1.5)

-Increased differences between two populations in different locations
-Decreased variation within a population

Which statement(s) about genetic drift is (are) false? (1.5)
-Genetic variation is unaffected by genetic drift
-New mutations that have no fitness effect are more likely to be fixed in small populations than in large
populations
-Genetic drift prevents the evolution of linkage disequilibrium between loci
-Evolution by random genetic drift proceeds faster in large populations than in small populations

-Genetic variation is unaffected by genetic drift
-Genetic drift prevents the evolution of linkage disequilibrium between loci
-Evolution by random genetic drift proceeds faster in large populations than in small populations

"Mitochondrial Eve" is the woman who represents the most recent common ancestor for all human
mitochondria; she probably lived about 125,000 years ago in Africa. If we imagine that humans experience a
major selective event, such that a small portion of the population have many more children and
grandchildren than everyone else, what might we be able to say about Mitochondrial Eve? (1.5)

-The identity of Mitochondrial Eve will probably move to a woman who lived more recently, because genes will
"coalesce" to a shared ancestor at a more recent date in the past
-The identity of Mitochondrial Eve could move to a recent ancestor of the individuals who have higher
reproductive success

Which observation(s) could be evidence of positive selection in DNA sequences? (1.5)

-A dN/dS ratio much greater than one
-Direct observation that individuals with specific alleles leave behind more descendants

Suppose you compare a region of DNA sequences in two closely related species. You find that, within one gene, the number of nonsynonymous differences between the two species is much greater than the number
of synonymous substitutions. Which of the following can you conclude? (1.5)

-The protein coded for by this gene has changed since the divergence of the two species from their common
ancestor
-The two species differ in the structure of the protein coded for by this gene
-Changes to the protein coded for by the gene have occurred faster than can be explained by mutation and random
genetic drift