Midterm II, BIO 350

Darwinian Medicine

November 5, 1998

NAME______________________________

Print your name legibly at the top of each page and be sure your test has 7 pages. Work through the test as rapidly as possible, answering the easiest questions first, and then return to the more difficult ones. Be sure to read each question carefully and completely, and think about your answer before writing. Use the back of the page if necessary to make notes or organize your answer. Do not hesitate to ask for clarification if you are unsure about the meaning of a question. Print your answers neatly in the space provided, using proper English sentences. Answers that are illegible or cannot be understood with a reasonable effort will not receive credit. Reread the questions and your answers before turning in your paper to be sure that each answer is complete and to the point. The test ends at 2:10 pm. The number of points possible is shown in parentheses after the number of the question.

1. (18) What caused the human population on Tristran da Cunha to evolve radically different allelic frequencies than those of the European population from which it was derived in 1816?

In general, how did the genetic composition of the Tristan da Cunha population change between 1816 and now?

What are the health consequences of this change in the genetic composition of the Tristan da Cunha population?

2. (20) Below is a life table and maternity schedule for a species that lives six years and then dies. The first year, 80% of the young die and then half die every year after that.

0 1.0 0

1 0.2 0

2 0.1 5

3 0.05 10

5 0.0125 10

6 0.00675 8

What is the expected lifetime reproductive success, R_o of this species?

Is this population increasing, decreasing, or staying the same size? (Circle one.)

Which gives a higher increase in reproductive success, doubling the survival rate for the first year of life, or doubling the reproductive rate during year 2? Explain your answer.

3. (16) Describe one line of evidence that mutations are random with respect to adaptation?

Why is it necessary to demonstrate that mutations are random with respect to adaptation to establish the importance of natural selection?

4. Deleted

5. (6) Why do we age (senesce)?

6. (5 ea.) Define each of the following terms and state why they are important in evolution. Do not define a term using the term.

GENE FLOW -

NATURAL SELECTION -

ADAPTATION -

PARSIMONY -

THEORY -

7. (6) What is the ultimate cause for the fundamental differences between men and women for their strategies to increase Darwinian fitness?

8. (20) What is the advantage for people to have lightly pigmented skin in boreal and polar (high latitude) regions and to have darkly pigmented skin in equatorial (low latitude) regions?

LIGHT IN HIGH LATITUDE REGIONS

DARK IN LOW LATITUDE REGIONS

What is the evidence that "Medium Dark" skin has evolved more than once in human populations?

Why do we think the ancestral character state for skin color in Homo sapiens is relatively dark?

9. (25) As people get older, they are prone to lower back pain and a series of pathologies of the abdominal organs, including intestinal blockage, visceral adhesion, hemorrhoids, and inguinal hernia. What advanced character state (=evolutionary change) of humans is responsible for these pathologies?

Explain how lower back pain and abdominal organ pathology resulted from the transition from the ancestral to the advanced character state in humans?

LOWER BACK PAIN -

ABDOMINAL ORGAN PATHOLOGY -

Circle one of the following "evolutionary legacies" and state what pathology(ies) the legacy produces.

OPTIONS: (A) Inverted retina, (B) Appendix, (C) Congestive heart failure, and (D) Vaginal opening through pelvis. (Circle one.)

PATHOLOGY(IES) -

10. (8) Name one intracellular mechanism to suppress the formation of a cancer cells.

What mechanism does the body have to destroy cancer cells once they form?

11. (18) Suppose you had a group of adults and every one was an Hb_sHb_a heterozygote (sickle/normal) for the -hemoglobin gene.

What zygotic (genotypic) frequencies would you expect their children to have at birth for -hemoglobin under Hardy-Weinberg equilibrium conditions?

Hb_sHb_s __________% Hb_sHb_a ___________% Hb_aHb_a __________%

In geographic regions in which Hb_s alleles occur at high frequencies, which of the genotypes above would increase in frequency as the children got older? (Circle one above.)

Why would the frequency of this genotype increase in these regions?

12. (18) What was the primary cause for rapid evolution of brain size within the genus Homo during the past 2 million years?

Why should evolution of increased brain size favor evolution of greater specialization of females for gathering and of males for hunting (i.e., foraging dimorphism) in Homo?

Why should evolution of increased brain size in Homo favor increased male fidelity to his mate (i.e., more stable pair bond)?