Transcript In-Text Art, Ch. 15, p. 289 (1) In-Text Art, Ch.

In-Text Art, Ch. 15, p. 289 (1)
In-Text Art, Ch. 15, p. 289 (2)
Figure 15.1 The Voyage of the Beagle
Figure 15.2 Milestones in the Development of Evolutionary Theory
Concept 15.1 Evolution Is Both Factual and the Basis of Broader Theory
Discuss the validity of the following statement:
When scientists speak of evolutionary theory, the word
“theory” has the same meaning as it does in everyday
language, referring to the fact that evolutionary theory is
just an idea that is not proven and backed by scientific
evidence.
Concept 15.1 Evolution Is Both Factual and the Basis of Broader Theory
Consider the validity of the following statement and then
select a correct answer from the options given:
When scientists speak of evolutionary theory, the word
“theory” has the same meaning as it does in everyday
language, referring to the fact that evolutionary theory is
just an idea that is not proven and backed by scientific
evidence.
a. True
b. False
c. I don’t understand the question.
Concept 15.2 Mutation, Selection, Gene Flow,
Genetic Drift, and Nonrandom Mating Result in Evolution
Biological evolution refers to changes in the genetic
makeup of populations over time.
Population—a group of individuals of a single species
that live and interbreed in a particular geographic area
at the same time.
Individuals do not evolve; populations do.
Concept 15.2 Mutation, Selection, Gene Flow,
Genetic Drift, and Nonrandom Mating Result in Evolution
Because of mutation, different forms of a gene, or alleles,
may exist at a locus.
Gene pool—sum of all copies of all alleles at all loci in a
population.
Allele frequency—proportion of each allele in the gene
pool.
Genotype frequency—proportion of each genotype
among individuals in the population.
Figure 15.3 A Gene Pool
Figure 15.3 A Gene Pool
Figure 15.4 Many Vegetables from One Species
Figure 15.5 Artificial Selection
Figure 15.6 Artificial Selection Reveals Genetic Variation
Figure 15.6 Artificial Selection Reveals Genetic Variation
Concept 15.2 Mutation, Selection, Gene Flow,
Genetic Drift, and Nonrandom Mating Result in Evolution
Genetic drift—random changes in allele frequencies
from one generation to the next.
In small populations, it can change allele frequencies.
Harmful alleles may increase in frequency, or rare
advantageous alleles may be lost.
Concept 15.2 Mutation, Selection, Gene Flow,
Genetic Drift, and Nonrandom Mating Result in Evolution
A population bottleneck—an environmental event
results in survival of only a few individuals.
Genetic drift can change allele frequencies.
Populations that go through bottlenecks loose much of
their genetic variation.
Concept 15.2 Mutation, Selection, Gene Flow,
Genetic Drift, and Nonrandom Mating Result in Evolution
Founder effect—genetic drift changes allele frequencies
when a few individuals colonize a new area.
Figure 15.7 A Population Bottleneck
Figure 15.7 A Population Bottleneck
Concept 15.2 Mutation, Selection, Gene Flow,
Genetic Drift, and Nonrandom Mating Result in Evolution
Sexual selection—mates are chosen based on
phenotype, e.g., bright-colored feathers of male birds.
There may be a trade-off between attracting mates (more
likely to reproduce) and attracting predators (less likely
to survive).
Concept 15.2 Mutation, Selection, Gene Flow,
Genetic Drift, and Nonrandom Mating Result in Evolution
Or, phenotype may indicate a successful genotype, e.g.,
female frogs are attracted to males with low-frequency
calls, which are larger and older (hence successful).
Studies of African long-tailed widowbirds showed that
females preferred males with longer tails, which may
indicate greater health and vigor.
Figure 15.8 What Is the Advantage?
Figure 15.9 Sexual Selection in Action
Figure 15.9 Sexual Selection in Action (Part 1)
Figure 15.9 Sexual Selection in Action (Part 2)
Concept 15.2 Mutation, Selection, Gene Flow, Genetic Drift, and Random Mating Result in
Evolution
Discuss the following scenarios with reference to whether or not they
correctly describe examples of the process we attribute to having
been first described by Charles Darwin - evolution by “natural
selection”:
• The development of a curved back over the period of your
lifetime
• Giraffes’ necks lengthening during their lifetime as they reach up
to high branches to eat the leaves of trees
• A drought affects an island where a population of a particular
finch species lives. The species naturally has a small amount of
variability in bill (beak) size. The drought results in finches with
larger bills surviving at a greater rate than those with smaller
bills, since the larger billed birds can crack open and eat very
tough seeds that the small billed individuals cannot.
• A mutation in an insect results in increased digestive efficiency
that allows females to obtain more energy from their food, and
convert that energy into larger eggs that are more likely to
survive, resulting in these females producing more surviving
offspring
Concept 15.2 Mutation, Selection, Gene Flow, Genetic Drift, and Random Mating Result in
Evolution
Which of the following scenarios correctly describe examples of the process we
attribute to having been first described by Charles Darwin - evolution by
“natural selection”:
a. The development of a curved back over the period of your lifetime
b. Giraffes’ necks lengthening during their lifetime as they reach up to
high branches to eat the leaves of trees
c. A drought affects an island where a population of a particular finch
species lives. The species naturally has a small amount of variability in
bill (beak) size. The drought results in finches with larger bills surviving
at a greater rate than those with smaller bills, since the larger billed
birds can crack open and eat very tough seeds that the small billed
individuals cannot.
d. A mutation in an insect results in increased digestive efficiency that
allows females to obtain more energy from their food, and convert that
energy into larger eggs that are more likely to survive, resulting in these
females producing more surviving offspring
e. Both c and d
Concept 15.3 Evolution Can Be Measured by Changes in Allele Frequencies
Evolution can be measured by change in allele
frequencies.
Allele frequency =
num berof copiesof allele in population
total num berof copiesof all alleles in population
Concept 15.3 Evolution Can Be Measured by Changes in Allele Frequencies
For two alleles at a locus, A and a, three genotypes are
possible: AA, Aa, and aa.
p = frequency of A; q = frequency of a
2 N AA  N Aa
p
2N
2 N aa  N Aa
q
2N
Figure 15.10 Calculating Allele and Genotype Frequencies
Figure 15.10 Calculating Allele and Genotype Frequencies
Concept 15.3 Evolution Can Be Measured by Changes in Allele Frequencies
For each population, p + q = 1, and q = 1 – p.
Monomorphic: only one allele at a locus, frequency = 1.
The allele is fixed.
Polymorphic: more than one allele at a locus.
Genetic structure—frequency of alleles and genotypes
of a population.
Concept 15.3 Evolution Can Be Measured by Changes in Allele Frequencies
Hardy–Weinberg equilibrium—allele frequencies do
not change across generations; genotype frequencies
can be calculated from allele frequencies.
If a population is at Hardy-Weinberg equilibrium, there
must be no mutation, no gene flow, no selection of
genotypes, infinite population size, and random
mating.
Concept 15.3 Evolution Can Be Measured by Changes in Allele Frequencies
At Hardy-Weinberg equilibrium, allele frequencies don’t
change.
Genotypes frequencies:
Genotype AA Aa aa
Frequency p2 2pq q2
Figure 15.11 One Generation of Random Mating Restores Hardy–Weinberg Equilibrium
Figure 15.11 One Generation of Random Mating Restores Hardy–Weinberg Equilibrium (Part 1)
Figure 15.11 One Generation of Random Mating Restores Hardy–Weinberg Equilibrium (Part 2)
Concept 15.3 Evolution Can Be Measured by Changes in Allele Frequencies
Probability of 2 A-gametes coming together:
p  p  p 2  (0.55)2  0.3025
Probability of 2 a-gametes coming together:
q  q  q 2  (0.45)2  0.2025
Overall probability of obtaining a heterozygote:
2 pq  0.495
Apply the Concept page 299
Evolution can be measured by changes in allele frequencies
Imagine you have discovered a new population of curly-tailed
lizards established on an island after immigrants have arrived
from several different source populations during a hurricane.
You collect and tabulate genotype data for the lactate
dehydrogenase gene (ldh) for each of the individual lizards
Use the table to answer the following questions.
1. Calculate the allele and genotype frequencies of ldh in this
newly founded population.
2. Is the population in Hardy-Weinberg equilibrium? If not,
which genotypes are over- or underrepresented? Given the
population’s history, what is a likely explanation for your
answer?
3. Under Hardy-Weinberg assumptions, what allele and
genotype frequencies do you predict for the next generation?
4. Imagine that you are able to continue studying this
population and determine the next generation’s actual allele
and genotype frequencies. What are some of the principal
reasons you might expect the observed allele frequency to
differ from the Hardy-Weinberg expectations you calculated
in question 3?
Apply the Concept, Ch. 15, p. 299
Concept 15.3 Evolution Can Be Measured by Changes in Allele Frequencies
Consider and discuss the following scenarios in relation to
Hardy–Weinberg equilibrium, and determine whether or
not allele frequencies are likely to change, leading to
evolution:
• An isolated and highly endangered population of 50
woodland caribou
• A large population of lizards whose males have red,
blue, or green tails; females preferentially mate with
red-tailed males
• A large population of fish in an isolated lake; every 5
years a flood results in some fish from a population in
an adjacent lake mixing with this population
Concept 15.3 Evolution Can Be Measured by Changes in Allele Frequencies
In which of the following scenarios are allele frequencies
are likely to change, leading to evolution, according to
Hardy–Weinberg assumptions:
a. An isolated and highly endangered population of 50
woodland caribou
b. A large population of lizards whose males have red,
blue, or green tails; females preferentially mate with
red-tailed males
c. A large population of fish in an isolated lake; every 5
years a flood results in some fish from a population in
an adjacent lake mixing with this population
d. All of the above
e. None of the above
Concept 15.4 Selection Can Be Stabilizing, Directional, or Disruptive
Natural selection can act on quantitative traits in three
ways:
• Stabilizing selection favors average individuals.
• Directional selection favors individuals that vary in
one direction from the mean.
• Disruptive selection favors individuals that vary in
both directions from the mean.
Concept 15.4 Selection Can Be Stabilizing, Directional, or Disruptive
Stabilizing selection reduces variation in populations, but
does not change the mean.
It is often called purifying selection—selection against
any deleterious mutations to the usual gene sequence.
Figure 15.12 Natural Selection Can Operate in Several Ways
Figure 15.12 Natural Selection Can Operate in Several Ways
Figure 15.12 Natural Selection Can Operate in Several Ways (Part 1)
Figure 15.12 Natural Selection Can Operate in Several Ways (Part 2)
Figure 15.12 Natural Selection Can Operate in Several Ways (Part 3)
Figure 15.13 Human Birth Weight Is Influenced by Stabilizing Selection
Figure 15.14 Long Horns Are the Result of Directional Selection
Figure 15.15 Disruptive Selection Results in a Bimodal Character Distribution
Figure 15.15 Disruptive Selection Results in a Bimodal Character Distribution
Concept 15.4 Selection Can Be Stabilizing, Directional, or Disruptive
A flock of 150 tiny orange and brown sparrows is blown off
course and ends up on a huge island where there is a lot
of open shrubby land adjacent to low hills with trees.
There are mammals, many plants, some insects, lizards,
and a few hawks, but there are no other small birds.
There are two types of plants with seeds edible for the
sparrows: a small-seeded tree and a large-seeded bush.
Discuss what you think might happen to this population of
birds over many generations with respect to the three
different types of selection discussed in the text:
• Stabilizing
• Directional
• Disruptive
Concept 15.4 Selection Can Be Stabilizing, Directional, or Disruptive
What you think might happen to this population of birds
over many generations (refer to graphs below)?
a. Stabilizing selection will operate on population beak
size.
b. Directional selection will operate on population beak
size.
c. Disruptive selection will operate on population beak
size.
d. Population beak size will not change; the birds will
maintain their original genetic diversity.
A
B
C
Concept 15.5 Genomes Reveal Both Neutral
and Selective Processes of Evolution
Types of mutations:
• Nucleotide substitution—change in one nucleotide
in a DNA sequence (a point mutation).
• Synonymous substitution—most don’t affect
phenotype because most amino acids are specified by
more than one codon.
• Nonsynonymous substitution—deleterious or
selectively neutral.
Concept 15.5 Genomes Reveal Both Neutral
and Selective Processes of Evolution
Substitution rates are highest at positions that do not
change the amino acid being expressed.
Substitution is even higher in pseudogenes, copies of
genes that are no longer functional.
Figure 15.16 When One Nucleotide Changes
Figure 15.16 When One Nucleotide Changes
Figure 15.16 When One Nucleotide Changes (Part 1)
Figure 15.16 When One Nucleotide Changes (Part 2)
Figure 15.17 Rates of Substitution Differ
Figure 15.17 Rates of Substitution Differ
Concept 15.5 Genomes Reveal Both Neutral
and Selective Processes of Evolution
Neutral theory—at the molecular level, the majority of
variants in most populations are selectively neutral.
Neutral variants must accumulate through genetic drift
rather than positive selection.
Concept 15.5 Genomes Reveal Both Neutral
and Selective Processes of Evolution
Rate of fixation of neutral mutations by genetic drift is
independent of population size.
1
2 N

N = population size 2 N
μ = neutral mutation rate
Concept 15.5 Genomes Reveal Both Neutral
and Selective Processes of Evolution
Relative rates of substitution types differ as a function of
selection:
• If similar, the corresponding amino acid is likely drifting
neutrally among states.
• If nonsynonymous substitution exceeds synonymous,
positive selection results in change in the
corresponding amino acid.
• If synonymous substitution exceeds nonsynonymous,
purifying selection resists change in the corresponding
amino acid.
Concept 15.5 Genomes Reveal Both Neutral and Selective Processes of Evolution
In a population of size N of a diploid organism, the rate of
fixation of neutral mutations () in this population is
given by the equation:
From this equation, discuss what can we deduce about the
influence of population size (N) on the rate of fixation of
neutral mutations in a population.
Concept 15.5 Genomes Reveal Both Neutral and Selective Processes of Evolution
In a population of size N of a diploid organism, the rate of
fixation of neutral mutations () in this population is
given by the equation:
From this equation, we can deduce that population size (N)
has _______ on the rate of fixation of neutral mutations?
a. an important effect
b. no effect
c. I don’t understand the question.
Concept 15.5 Genomes Reveal Both Neutral
and Selective Processes of Evolution
Evolution of lysozyme:
Lysozyme digests bacteria cell walls; found in almost all
animals as a defense mechanism.
Some mammals are foregut fermenters, which has
evolved twice—in ruminants and leaf-eating monkeys
(langurs). Lysozyme in these lineages has been
modified to rupture some bacteria in the foregut to
release nutrients.
Concept 15.5 Genomes Reveal Both Neutral
and Selective Processes of Evolution
Lysozyme-coding sequences were compared in foregut
fermenters and their non-fermenting relatives, and
rates of substitutions were determined.
The rate of synonymous substitution in the lysozyme
gene was much higher than nonsynonymous,
indicating that many of the amino acids are evolving
under purifying selection.
Concept 15.5 Genomes Reveal Both Neutral
and Selective Processes of Evolution
Replacements in lysozyme happened at a much higher
rate in langur lineage.
Lysozyme went through a period of rapid change in
adapting to the stomachs of langurs.
Lysozymes of langurs and cattle share five convergent
amino acid replacements, which make the protein
more resistant to degradation by the stomach enzyme
pepsin.
Figure 15.18 Convergent Molecular Evolution of Lysozyme
Figure 15.18 Convergent Molecular Evolution of Lysozyme
Figure 15.18 Convergent Molecular Evolution of Lysozyme (Part 1)
Concept 15.5 Genomes Reveal Both Neutral
and Selective Processes of Evolution
Lysozyme in the crop of the hoatzin, a foregut-fermenting
bird, has similar adaptations as those of langurs and
cattle.
Figure 15.18 Convergent Molecular Evolution of Lysozyme (Part 2)
Apply the concept page 305
Genomes reveal both neutral and selective processes of evolution
Analysis of synonymous and nonsynonymous substitutions in
protein-coding genes can be used to detect neutral evolution,
positive selection, and purifying selection. An investigator
compared many gene sequences that encode the protein
hemagglutinin (a surface protein of influenza virus) sampled
over time, and collected this data.
Use the table to answer the questions.
1. Which codon positions encode amino acids that have
probably changed as a result of positive selection? Why?
2. Which codon position is most likely to encode an amino acid
that drifts neutrally among states?
3. Which codon positions encode amino acids that have
probably changed as a result of purifying selection?
Apply the Concept, Ch. 15, p. 305
Figure 15.19 A Heterozygote Mating Advantage
Figure 15.19 A Heterozygote Mating Advantage (Part 1)
Figure 15.19 A Heterozygote Mating Advantage (Part 2)
Concept 15.6 Recombination, Lateral Gene Transfer,
and Gene Duplication Can Result in New Features
Sexual reproduction results in new combinations of
genes and produces genetic variety that increases
evolutionary potential.
But in the short term, it has disadvantages:
• Recombination can break up adaptive combinations of
genes
• Reduces rate at which females pass genes to
offspring
• Dividing offspring into genders reduces the overall
reproductive rate
Concept 15.6 Recombination, Lateral Gene Transfer,
and Gene Duplication Can Result in New Features
Why did sexual reproduction evolve? Possible
advantages:
• It facilitates repair of damaged DNA. Damage on one
chromosome can be repaired by copying intact
sequences on the other chromosome.
• Elimination of deleterious mutations through
recombination followed by selection.
Concept 15.6 Recombination, Lateral Gene Transfer,
and Gene Duplication Can Result in New Features
• In asexually reproducing species, deleterious
mutations can accumulate; only death of the lineage
can eliminate them
Muller called this the genetic ratchet—mutations
accumulate or “ratchet up” at each replication;
Muller’s ratchet.
Concept 15.6 Recombination, Lateral Gene Transfer,
and Gene Duplication Can Result in New Features
• The variety of genetic combinations in each generation
can be advantageous (e.g., as defense against
pathogens and parasites).
Sexual recombination does not directly influence the
frequencies of alleles. Rather, it generates new
combinations of alleles on which natural selection can
act.
Concept 15.6 Recombination, Lateral Gene Transfer, and Gene Duplication Can Result in New
Features
Why sex is good
Scientists have long puzzled over why sex has evolved, given the
disadvantages of sex:
1. Gene mixing tends to break up favorable combinations, and why
break up a good thing?
2. Asexual reproduction is twice as efficient as sexual reproduction
at passing on genes to the next generation. Every time a sexual
mother produces a child, only one-half of the child’s genes
come from the mother; the other half are from the father.
Reproducing parthenogenetically, an asexual mother passes on
to her child a complete copy of her genes. It stands to reason
that such populations should rapidly out-reproduce a sexual
population, since every individual is a female that can reproduce
offspring.
Concept 15.6 Recombination, Lateral Gene Transfer, and Gene Duplication Can Result in New
Features
Why sex is good (continued)
For these two reasons, it seems clearly disadvantageous for individuals
to reproduce sexually! Yet sex has evolved and some kind of genetic
recombination (sex) occurs and retained in most organisms.
German biologist August Weismann proposed one possible
explanation for this conundrum, suggesting that sex increases
advantageous genetic variation.
When two different individuals mate by joining their gametes together,
they produce a brand new genetic mixture and this promotes
evolutionary adaptation. In other words, sex is good because it
allows you to evolve more quickly when conditions change.
Concept 15.6 Recombination, Lateral Gene Transfer, and Gene Duplication Can Result in New
Features
Why sex is good (continued)
A team of scientists at the Imperial College London investigated the
hypothesis that the genetic recombination that results from sexual
reproduction is advantageous. They published their results in Nature
magazine in March 2005.
They performed an experiment on yeasts, which are single-celled fungi.
Yeasts can reproduce both sexually and asexually, are easy to keep
in the lab, and reproduce rapidly.
Yeasts normally reproduce asexually, but will reproduce sexually when
they are stressed (starved, high temperatures, etc.). The team of
scientists did not want this sexual/asexual switching to occur so they
genetically manipulated one asexual strain. They deleted the two
genes required for normal meiosis, so that sexual reproduction was
impossible. Now they had two pure strains of yeast—an asexual
strain and a sexual strain.
Concept 15.6 Recombination, Lateral Gene Transfer, and Gene Duplication Can Result in New
Features
Why sex is good (continued)
The team compared the reproductive rate of the asexual vs. the sexual
yeasts in two different environments: one benign and one harsh.
• The benign environment had plenty of nutrients although glucose
was limited so that growth was not uncontrolled.
• The harsh environment had the same glucose concentration but
was at a higher temperature and had more demanding osmotic
conditions (e.g., the water was more salty).
Evolutionary “fitness” was measured by comparing the growth rate of
the asexual and sexual strains of yeast.
Concept 15.6 Recombination, Lateral Gene Transfer, and Gene Duplication Can Result in New
Features
On the graph below, plot the results you would expect if Weismann’s
hypothesis were correct. Plot the changes in fitness values over time
in the populations of sexual yeasts in benign conditions, asexual
yeasts in benign conditions, asexual yeasts in harsh conditions, and
sexual yeasts in harsh conditions.
Concept 15.6 Recombination, Lateral Gene Transfer, and Gene Duplication Can Result in New
Features
From this graph showing the
experimental results of growing
genetically manipulated sexual and
asexual yeast strains in harsh
versus benign conditions, we can
interpret that:
a. Sexual reproduction is
advantageous in harsh
environments.
b. Asexual reproduction is always
equally advantageous to sexual
reproduction.
c. Asexual reproduction is always
advantageous to sexual
reproduction.
d. There is no difference in fitness
between sexual and asexually
reproducing yeasts.
e. Sexual reproduction is always
advantageous to asexual
reproduction.
Concept 15.5 Genomes Reveal Both Neutral
and Selective Processes of Evolution
The amount of nonconding DNA may be related to
population size.
Noncoding sequences that are only slightly deleterious
are likely to be purged by selection most efficiently in
species with large population sizes.
In small populations genetic drift may overwhelm
selection against these sequences.
Figure 15.20 Genome Size Varies Widely
Figure 15.21 A Large Proportion of DNA Is Noncoding
Concept 15.6 Recombination, Lateral Gene Transfer,
and Gene Duplication Can Result in New Features
Lateral gene transfer—individual genes, organelles, or
genome fragments move horizontally from one lineage
to another.
• Species may pick up DNA fragments directly from the
environment.
• Genes may be transferred to a new host in a viral
genome.
• Hybridization results in the transfer of many genes.
Concept 15.6 Recombination, Lateral Gene Transfer,
and Gene Duplication Can Result in New Features
Lateral gene transfer can be advantageous to a species
that incorporates novel genes.
Genes that confer antibiotic resistance are often
transferred among bacteria species.
Concept 15.6 Recombination, Lateral Gene Transfer,
and Gene Duplication Can Result in New Features
Gene duplication—genomes can gain new functions.
Gene copies may have different fates:
1. Both copies retain original function (may increase
amount of gene product).
2. Gene expression may diverge in different tissues or at
different times in development.
Concept 15.6 Recombination, Lateral Gene Transfer,
and Gene Duplication Can Result in New Features
3. One copy may accumulate deleterious mutations and
become a functionless pseudogene.
4. One copy retains original function, the other changes
and evolves a new function.
Concept 15.6 Recombination, Lateral Gene Transfer,
and Gene Duplication Can Result in New Features
Sometimes entire genomes may be duplicated, providing
massive opportunities for new functions to evolve.
In vertebrate evolution, genomes of the jawed
vertebrates have 4 diploid sets of many genes.
Two genome-wide duplication events occurred in the
ancestor of these species. This allowed specialization
of individual vertebrate genes.
Figure 15.22 A Globin Family Gene Tree
Figure 15.22 A Globin Family Gene Tree
Figure 15.23 In Vitro Evolution
Figure 15.23 In Vitro Evolution
Figure 15.23 In Vitro Evolution (Part 1)
Figure 15.23 In Vitro Evolution (Part 2)
Concept 15.7 Evolutionary Theory Has Practical Applications
Discuss the validity of following statements given what you
have learned about evolution:
• Pesticide resistance exhibited by insects in
agricultural settings provides direct evidence that
evolution is occurring.
• Antibiotic resistance is an example of evolution that
helps to keep pharmaceutical companies in business.
• In vitro evolution at the molecular level, as described
in Figure 15.23 of the textbook, is analogous to the
artificial selection of pigeons and dogs that Darwin
was interested in more than two centuries ago.
Concept 15.7 Evolutionary Theory Has Practical Applications
Given what you have learned about evolution, which of the
following statements is true?
a. Pesticide resistance exhibited by insects in
agricultural settings provides direct evidence that
evolution is occurring.
b. Antibiotic resistance is an example of evolution that
helps to keep pharmaceutical companies in business.
c. In vitro evolution at the molecular level, as described
in Figure 15.23 of the textbook, is analogous to the
artificial selection of pigeons and dogs that Darwin
was interested in more than two centuries ago.
d. All of the above
e. None of the above
Figure 15.24 Evolutionary Analysis of Surface Proteins Leads to Improved Flu Vaccines
Figure 15.24 Evolutionary Analysis of Surface Proteins Leads to Improved Flu Vaccines