FINAL EXAMINATION – Thursday December 7, 2006

NAME _________________________________
SECTION _____________________
Bio 175 – FALL 2006
FINAL EXAMINATION – Thursday December 7, 2006
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, 50
points total)
1. The geographic distribution of salamander species belonging to the genus Ensatina
throughout California is thought to have been generated by
a. allopatric speciation.
b. peripatric speciation.
X. parapatric speciation.
d. sympatric speciation.
e. none of the above.
2. The discovery of undescribed amino acids in meteorites provides support for which step of the
chemical theory for the origin of life?
a. protobionts  true cells.
X. inorganic molecules  organic molecules.
c. inorganic molecules  biological polymers.
d. biological polymers  replicating systems.
e. replicating systems  protobionts.
3. In the hominid fossil record, Homo erectus is believed to have evolved from
X. Homo ergaster.
b. Homo habilis.
c. Australopithecus robustus.
d. Australopithecus afarensis.
e. Australopithecus africanus.
4. The Cambrian explosion occurred about
a. 3.8 billion years ago.
b. 1.8 billion years ago.
X. 520 million years ago.
d. 250 million years ago.
e. 65 million years ago.
5. The principle of maximum parsimony discriminates among phylogenetic trees on the basis of
differences in
a. the number of synapomorphic characters.
X. the number of inferred evolutionary changes.
c. maximum likelihood scores.
d. the overall similarity among taxa.
e. the overall lengths of their branches.
6. Kin selection has been proposed to account for the evolution of
a. parental care.
b. eusociality in insects.
c. cooperative breeding in birds.
d. altruistic behaviors.
X. all of the above.
7. In protogynous species, individuals
a. are simultaneously male and female throughout their entire lives.
b. begin life as males and at a later age switch to become females.
X. 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.
8. Amino acid sites in the influenza A virus’s hemagglutinin gene that our immune system
recognizes and remembers are called
X. antigenic sites.
b. non-antigenic sites.
c. immunogenic sites.
d. allergenic sites
e. none of the above.
9. The evolutionary species concept can be used to identify
a. sibling species.
b. cryptic species.
X. fossil species.
d. species capable of freely hybridizing.
e. none of the above.
10. Hypermorphosis refers to a form of
a. peramorphosis resulting from a slower rate of development.
b. paedomorphosis resulting from a slower rate of development.
X. peramorphosis resulting from an later cessation of growth.
d. paedomorphosis resulting from an early cessation of growth.
e. none of the above.
NAME _________________________________
SECTION _____________________
11. In the majority of species, sexual selection occurs more intensely in males than in females
a. parental care is extremely common in nature.
b. males invest more in their offspring than females.
X. a male’s total fitness is limited by the number of females he can mate.
d. a male’s total fitness is not limited by the number of females he can mate.
e. none of the above.
12. According to the rate-of-living theory of aging
a. species with high metabolic rates should have extremely long life spans.
b. a trade-off should exist between early reproduction and longevity.
X. attempts to increase life span by artificial selection should not be effective.
d. aging and death are caused by late-acting deleterious mutations.
e. none of the above.
13. A monophyletic group of taxa is defined as having
X. a common ancestral species and includes all descendants of that ancestor.
b. 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.
14. According to molecular data, humans and chimpanzees last shared a common ancestor about
a. 20 million years ago.
b. 13 million years ago.
c. 8 million years ago.
X. 5 million years ago.
e. 2 million years ago.
15. Homeotic genes
a. occur in multigene families.
b. possess a highly conserved 180 bp homeodomain.
c. exhibit spatial and temporal colinearity.
d. control the timing and degree of expression of genes determining body plans.
X. all of the above.
16. Adaptive radiations occur primarily through a relaxation of
a. antagonistic coevolution among species.
b. mutualistic interactions among species.
c. intraspecific competition within species.
X. interspecific competition among species.
e. none of the above.
17. The evolution of a stable 1:1 sex ratio is an example of
a. directional selection.
X. frequency-dependent selection.
c. overdominance.
d. purifying selection.
e. none of the above.
18. Infanticide is an example of
a. intersexual selection acting to benefit the species.
b. intrasexual selection acting to benefit the species.
c. intersexual selection acting to benefit the individual.
X. intrasexual selection acting to benefit the individual.
e. none of the above.
19. In the Belding’s ground squirrel, alarm calls
X. are given more frequently by males than females.
b. are given more frequently by females than males.
c. are given more frequently in groups of non-related individuals.
d. do not impose a fitness cost.
e. none of the above.
20. Identifying monophyletic groups is fundamental for the
a. biological species concept.
X. phylogenetic species concept.
c. morphological species concept.
d. recognition species concept.
e. cohesion species concept.
21. The trade-off hypothesis for the evolution of virulence predicts that a pathogen will evolve to
a. transmitted vertically (i.e., from parent to offspring).
b. transmitted horizontally (i.e., from individual to individual).
c. more virulent over time.
d. less virulent over time.
X. optimally balanced to maximize its own fitness at the expense of its host.
22. A new tetraploid plant species formed by the retention of an extra set of chromosomes from
individuals of the same species is called an
X. autopolyploid.
b. allopolyploid.
c. autotroph.
d. automorph.
e. none of the above.
NAME _________________________________
SECTION _____________________
23. Intrasexual selection may lead to the evolution of
a. elaborate courtship displays by males.
b. exaggerated male secondary characters (e.g., tail lengths in birds).
c. bright coloration in males.
X. increased body sizes of males relative to females.
e. none of the above.
24. Which of the following observation supports the RNA world hypothesis?
a. RNA molecules can possess catalytic activities.
b. RNA plays an important role in protein synthesis.
c. RNA is involved in DNA replication.
d. deoxyribonucleotides are synthesized from ribonucleotide precursors.
X. all of the above.
25. Female African widowbirds strongly prefer to mate with males having long tails. According
to the good genes hypothesis, males having the longest tails
X. are genetically superior to other males.
b. are genetically inferior to other males.
c. are exploiting a pre-existing bias in females.
d. are being exploited by females that prefer long tails.
e. none of the above.
Part II. Short Answers. Please answer only in the space provided. (One or two sentences
will suffice for full points!) (30 points total)
1. (a) What is the evolutionary theory of aging? (3 points)
The evolutionary theory of aging posits that aging and death are attributable to inability of natural
selection to prevent cell and tissue damage from occurring later in life after the peak reproductive
(b) Briefly describe an observation or study that has provided support for the evolutionary theory
of aging. (3 points)
Here are 3 from lecture or the book – each worth 1.5 pts.
1. Hughes’s experiment in Drosophila showing that the magnitude of inbreeding depression
increases with age.
2. The age-1 gene in C. elegans and the Indy gene in D. melanogaster both exhibit antagonistic
3. Rose and Charlesworth’s Drosophila experiment in which selecting for early reproduction
caused reduced longevity. Gustafsson and Part’s experiments on collared flycatchers found the
same trade-off.
2. (a) What was the Cambrian explosion? (2 points)
The rapid appearance (over a 10 to 15 MY period) of large multicellular animals in the Cambrian
period (about 520 MYA). (This date is not necessary for complete pts.)
(b) What three factors might have contributed to the Cambrian explosion? (3 points)
1 pt each
Any 3 of
1. an increase in oxygen concentration in the oceans enabled larger organisms to evolve.
2. the evolution of hard parts (exoskeletons and shells).
3. the evolution of eyes.
4. diversification of homeotic genes enabling more complex body plans to evolve.
3. (a) What is a homologous character? (2 points)
A character possessed by two or more species/taxa that has been inherited from a common
(b) List three reasons why characters may not be homologous. (3 points)
1 pt each
1. the character evolved by convergent evolution.
2. the character evolved by parallel evolution.
3. the character has experienced reversals.
NAME _________________________________
SECTION _____________________
4. (a) What is paedomorphosis ? (3 points)
Paedomorphosis is “underdevelopment” and involves the retention of juvenile characters into
(b) Describe two ways that paedomorphosis can arise and provide an example for each. (4 points)
2 pts each
Paedomorphosis can arise from a decreased rate of development. This is called neoteny.
Example: The axolotl is neotenic because it retains external gills and a tail fin as an adult.
Paedomorphosis can also arise by a earlier offset time of growth. This is called progenesis.
Example: dwarf salamanders (genus Thorius).
5. (a) What is the African replacement hypothesis for the evolution of modern humans? (3 pts)
According to the AR hypothesis, an early (1.8 MYA) wave of modern humans emerged from
Africa that was followed by a second wave from Africa very recently (<200,000 years ago). The
second expansion from Africa resulted in the complete replacement of the archaic populations
with no detectable interbreeding.
(b) Briefly describe two observations that support the African replacement hypothesis. (4 pts)
2 pts each
Any 2 of:
1. Applying a molecular clock, the common ancestor of extant human populations dates to
roughly 150,000 years ago.
2. An African ancestry has been observed for all genes sampled from extant populations.
3. African populations possess greater levels of allelic diversity than any other extant
NAME _________________________________
SECTION _____________________
Part III. Long Essay. Please answer one of the following three questions (20 points)
1. In recent years, there has been a growing interest in the role that sexual selection might play as
a major “engine” of speciation. This question has two parts. First, briefly describe the different
modes of speciation emphasizing their similarities and/or differences. Second, discuss the
various ways that sexual selection can (i) contribute to the evolution of reproductive isolating
mechanisms, and (ii) affect the outcome of secondary contact between two formerly allopatric
NAME _________________________________
SECTION _____________________
2. Gould and Eldredge’s (1972) theory of punctuated equilibrium (PE) continues to generate
controversy among evolutionary biologists and paleontologists. This question also has two parts.
First, briefly review the observations that led Gould and Eldredge to propose the theory of PE
and the form of speciation they believed may have been involved. Second, discuss the features
of PE that represent challenges to microevolutionary theory, and those that can easily be
accommodated by existing theory. Please cite examples wherever possible.
NAME _________________________________
SECTION _____________________
3. Much of life-history theory is dominated the principle of “trade-offs”. Yet again, this
question has two parts. First, explain why trade-offs are to be expected among different lifehistory traits. Second, discuss in detail two examples of the how trade-offs affect specific lifehistory traits covered in class or discussed in the textbook.