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Bio 175 – FALL 2004
EVOLUTION
FINAL EXAMINATION – Monday December 6, 2004
GENERAL INSTRUCTIONS
1. Write your NAME ON EVERY PAGE and ANSWER ONLY IN THE SPACE
PROVIDED.
2. Please read the question carefully before answering.
3. Be CONCISE but COMPLETE in your answers.
Part I. Multiple choice. Circle the one BEST answer for each question (2 points each, 30
points total)
1. Progenesis refers to a form of
a. peramorphosis resulting from a slower rate of development
b. paedomorphosis resulting from a slower rate of development
c. peramorphosis resulting from an early cessation of growth
X paedomorphosis resulting from an early cessation of growth
e. none of the above
2. The first eukaryotes appear in the fossil record about
a. 4.5 billion years ago
b. 3.8 billion years ago
X 1.8 billion years ago
d. 540 million years ago
e. none of the above
3. A paraphyletic group of taxa is defined as having
a. a common ancestral species and includes all descendants of that ancestor
X a common ancestral species but omits some descendants of that ancestor
c. more than one ancestral species
d. no common ancestral species
e. none of the above
4. Elevated rates of amino acid replacement substitutions at antigenic sites in the hemagglutinin
gene of the influenza A virus is a good example of
a. negative selection
X positive selection
c. overdominant selection
d. purifying selection
e. none of the above
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5. Evidence supporting the chemical theory for the origin of life includes
a. the laboratory experiments of Stanley Miller at the University of Chicago in 1953
b. the synthesis of various biological polymers on the surfaces of clays
c. the discovery of organic compounds in meteorites
d. in vitro selection experiments on populations of RNA molecules in the laboratory
X all of the above
6. In protandrous species, individuals
a. are simultaneously male and female throughout their entire lives
X begin life as males and at a later age switch to become females
c. begin life as females and at a later age switch to become males
d. begin life as simultaneous hermaphrodites and at a later age switch to become males
e. none of the above
7. Unlike mitochondria, chloroplasts have been found to be
a. monophyletic
X polyphyletic
c. paraphyletic
d. periphyletic
e. none of the above
8. The biological species concept can be used to identify
a. asexual species
X cryptic species
c. fossil species
d. species capable of freely hybridizing
e. all of the above
9. Ring species are believed to be formed by the process of
a. allopatric speciation
X parapatric speciation
c. peripatric speciation
d. sympatric speciation
e. polyploid speciation
10. The formation of the supercontinent Pangaea may have contributed to which mass extinction
event?
a. the end-Ordovician
b. the late-Devonian
X the end-Permian
d. the end-Triassic
e. the Cretaceous-Tertiary (KT)
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11. Eusociality has evolved in
a. ants
b. paper wasps
c. snapping shrimp
d. naked mole-rats
X all of the above.
12. In the marine environment, species that survive mass extinctions tend to have
a. tropical distributions
b. large body sizes
c. extensive geographic ranges
d. highly specialized lifestyles
X all of the above
13. In the hominid fossil record, Homo habilis is believed to have evolved from
a. Homo ergaster
b. Homo erectus
c. Australopithecus robustus
d. Australopithecus afarensis
X Australopithecus africanus
14. Following secondary contact, the evolution of additional prezygotic isolating mechanisms to
“complete” the speciation process is called
a. hybrid release
b. hybrid assimilation
c. recapitulation
X reinforcement
e. none of the above
15. Intersexual selection can result in the evolution of
a. alternative male reproductive strategies.
b. a larger adult body size of the male relative to the female.
c. sperm competition among males.
X elaborate courtship displays by males.
e. none of the above.
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Part II. Distinctions. Briefly show that you understand the difference(s) between the two
terms in each question. (5 points each; 25 points total).
1. The evolutionary theory of aging vs. the rate-of-living theory of aging
- the ROL theory posits that natural selection has acted to maximize lifespan – it can’t
increase it any further.
- the evolutionary theory argues that selection cannot act to prevent aging and death since
these occur well after the peak reproductive period.
- there is also a difference in mechanism – the ROL theory holds that aging is caused by the
action of harmful by-products of cellular metabolism (e.g., free radicals) whereas the
evolutionary theory postulates two mechanisms (late onset deleterious genes and
antagonistic pleiotropy)THIS IS MORE THAN REQUIRED FOR FULL POINTS!
2. The African replacement model vs. the hybridization/assimilation model of human evolution
- under the AR model, there was a complete replacement of archaic human populations by
a recent (150,000 ya) second expansion out of Africa by modern humans.
- the HA model posits that there was not a complete replacement but some introgression
and assimilation of both groups. There is no strong molecular evidence for the HA model
but is for the AR model.
3. The coincidental evolution hypothesis vs. the trade-off hypothesis for the evolution of
virulence
- the CE hypothesis predicts that the virulence of a certain pathogen is not due to any longterm coevolution between it and humans. Instead, the virulence is determined by the
natural enemies of the pathogen in its native environment.
- under the T-O hypothesis, the level of virulence is shaped by long-term coevolution to
represent a balance between the harm done to the host and the reproductive rate of the
pathogen in the host (which strongly determines its fitness).
4. The sensory bias hypothesis vs. the good genes hypothesis
- according to the GG hypothesis, male characters evolve to act as honest signals of genetic
quality. Females thus benefit from selecting high quality males as mates.
- according to the SB hypothesis, male characters evolve to exploit some pre-existing female
preference for those characters. Thus females do not benefit from selecting males with the
character in question – in fact, the opposite may be the case.
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5. Punctuated equilibrium vs. phyletic gradualism
- according to PE, morphological change in the fossil record does not occur gradually but
occurs rapidly at the time of speciation. After new species appear they exhibit stasis.
- under the standard model of gradualism morphological changes occur slowly and are not
limited to times of speciation. There is also no tendency for stasis.
Part III. Short Answers. Please answer only in the space provided. (One or two sentences
will suffice for full points!) (25 points total)
1. (a) What is kin selection? (3 points)
- kin selection refers to the “indirect” component of fitness. This indirect component
represents the gain in fitness realized by relatives made possible by an individual’s
altruistic act.
(b) What is Hamilton’s inequality? (3 points)
- Hamilton’s inequality predicts that an altruistic behavior can evolve when the cost to the
individual performing the act (C) outweighs the benefit to the recipient (B) depending on
the degree of relatedness (r) between the two: Br – C > 0 (or rB > C).
If students give the equation but do not define the terms, give 1.5 points.
(c) State two assumptions of Lack’s hypothesis that are likely incorrect (2 points)
I mentioned three in class:
1. no trade-offs between reproductive efforts across consecutive years
2. clutch size only affects viability
3. no year-to-year variation in optimal clutch size
3.(a) What is a homeotic gene? (3 points)
- homeotic genes are regulatory proteins (transcription factors) that function to control the
developmental process by specifying the “identity” of cells in space and time.
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(b) What evidence suggests that homeotic genes played a role in the “Cambrian explosion”? (3
points)
- since homeotic genes determine body plans and there was an explosion of different types
of animals in the Cambrian it is logical that homeotic genes were involved.
- consistent with the “new genes – new bodies” hypothesis there is an increased number of
homeotic genes in more complex groups that radiated in the Cambrian.
4. (a) What is a ribozyme? (3 points)
- a ribozyme is a RNA molecule capable of catalyzing a chemical reaction similar to
enzymes (BONUS to anyone saying these involve the formation or breakdown of
phophodiester bonds).
(b) What two findings suggest that prokaryotes evolved between 3.5 and 4.0 billion years ago? (2
points)
1. fossil stromatolites date to 3.5 bya and are very similar to those formed today by
cyanobacteria.
2. carbon isotope data with a higher 12C to C13 ratio in organic deposits 3.8 bya confirm
that it was fixed by photosynthesis.
5. (a) What is homoplasy? (3 points)
- homoplasy occurs when a character possessed by two or more species has not been
inherited from a common ancestor. In other words, the character evolved independently in
each lineage.
(b) Name three forms of homoplasy and provide an example of each (3 points)
1. convergent evolution – the evolution of eyes in cephalopods and vertebrates
2. parallel evolution – the evolution of wing patterns in moths and butterflies
3. evolutionary reversals – back mutations at the DNA sequence level.
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Part IV. Long Essay. Please answer one of the following two questions (20 points)
1. The use of phylogenetic trees is becoming widespread in many areas of evolutionary biology.
In fact, in many specific areas of study (such as applying the “comparative method”) one cannot
begin to properly address questions without first knowing the phylogeny of the group! This
question has two parts. First, briefly describe the two main approaches used to reconstruct
phylogenetic trees and identify the pros and cons associated with each method. Second, discuss
two examples from class (either lecture or textbook) in which phylogenetic trees have been used
to examine specific evolutionary questions that extend beyond inferring taxonomic relationships.
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2. You have been asked to testify in Sacramento as an expert witness for the defense in a legal
case brought by a California group that wants creation science taught alongside evolution in the
state’s high schools. Due to time constraints, you have been asked to prepare two arguments that
you feel make the strongest possible case supporting the biological fact of evolution. Clearly
discuss the two best arguments that you would make in court drawing heavily from topics or
examples discussed in lecture or the textbook. [Note: you are not being asked to refute the
creationist’s arguments (this is being done by other scientists) but to present material supporting
evolution.]
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