SELECTED STUDENT LAB EXAM QUESTIONS

These ten questions were chosed from the Laboratory Questions submitted by students. Two of these questions (#3 and #6) were used on the final examination. Other questions submitted by students were used on the lab exam. Question #1 has been incorporated into the lab manual.

Imagine that uncooperative co-evolution between the wolf and its prey, the rabbit, occurs. The rabbit's hopping speed increases and, in order to survive, the wolves' maximum running speed experiences selective pressure to increase as well.
- In polygenic inheritance, a specific trait is affected by many genes. Wolves display polygenic inheritance in their running speed. Suppose that running speed is determined by the additive contributing effects of five different genes. Each gene affects one trait which in turn affects running speed.
- Suppose the five genes determine the following traits:
  1. the proportion of fast twitch (power) vs slow twitch (endurance) muscle fibers in muscle tissue.
  2. the wolf's overall muscle mass relative to its body size
  3. leg bone length
  4. relative speed of neuron signal to muscle contraction
  5. leanness of the animal
- For each gene, describe the alternation which would need to occur in order for that gene to contribute to increasing the maximum running speed. List the costs and benefits to the individual wolf of such alternations.
Gregor Johann Mendel developed two Mendelian Inheritance laws. Give a short summary of each law and state clearly under what circumstances each law applies.
In a particular genus of fish, Xiphophorus, exaggerated sword-like caudal fin appendages are exhibited in male fish. Molecular phylogeny of this genus, based on mitochondrial and nuclear DNA sequences, indicates that this trait has originated and been lost repeatedly. The female fish of the genus exhibit no such trait, and display a simpler caudal fin structure than the males.
1. Name the type of selection that favors the presence of the exaggerated male caudal fin extensions.
2. Suggest a hypothesis (stating the 'ultimate' cause) for the repeated origination and loss of this unusual trait.
3. Why would a female Xiphophorus likely choose a mating partner with exaggerated caudal fin extensions over one that does not possess this trait?
Fever is a common response to infection in many animals. Some lizards purposely move to a hot, sunny area when ill, a behavior called 'behavioral fever'. Research shows that lizards, kept at warm temperatures approximating behavioral fever by manipulation of ambient temperatures, recover sooner from infection than lizards kept at cooler temperatures.
- Discuss the following concepts in relation to this example:
  1. costs and benefits of this behavior
  2. ultimate causation of this behavior
  3. proximate causation of this behavior

In the book 'The Restaurant at the End of the Universe', one of the Hitchhiker's Guide to the Galaxy books, Douglas Adams describes an interesting scenario. According to the story, about two million years ago, thousands of humans from the planet Golgafrincham found themselves permanently marooned on a small blue planet in an unfashionable corner of the galaxy when their space ship crashed. That planet was Earth, and those Golgafrinchams were our ancestors.

Using your knowledge from BISC 102, use evidence from the fossil record, cellular structure, human anatomy and embryology to convince someone that it is unlikely that humans evolved on Golgafrincham and appeared suddenly on Earth.
Adams suggests that the Golgafrinchams who landed here two million years ago are very much the same as modern humans. Using your understanding of natural selection and adaptation, explain why it is unlikely that humans would have stayed the same for two million years after their sudden appearance on Earth.

A class of biology students is asked to make up questions for the final lab exam. individual students submitting challenging questions will receive high marks on the 10% allocated to this assignment. If all students submit questions that are very easy to answer, most students will do well on the lab exam and will get many more marks out of 25 than the few extra marks they can get out of 10 by submitting challenging lab questions.

From an evolutionary standpoint, will the students create easy lab questions to benefit the entire class, or will the students create challenging questions to benefit themselves (and hope that the rest of the class chooses to create easy questions)?

If the earth's land masses were to come together again to form Pangea, would biological diversity increase, decrease or stay the same? Give two examples to support your answer.
What features would put an organism at an advantage in this situation?
What features would put an organism at a disadvantage in this situation?

In the butterfly Asterocampa leilia, males adopt a 'sit and wait' strategy for detecting mates. However, these butterflies are ectothermic. Therefore, body orientation, posture and perch choice have dramatic effects on body temperature. Sitting in a way that would increase the likelihood of seeing a potential mate also maximizes heat absorption. On a hot day, sitting in this position may result in overheating and death of the male.

How might selection affect the perch and posture male butterflies would choose on a hot day? Use the concept of tradeoffs in your discussion.
Hypothetically, assume that a group of males waiting for mates are all genetically related. How might they show altruistic behaviors on a hot day? How would an individual male benefit from such behaviors?

A relatively harmless spider living in the wild has a 33% chance of surviving to reproduce. Another spider from the same species has a genetic mutation, giving it the outward appearance of a highly venomous spider. The mutant spider has an 80% chance of surviving to reproduce.

Why might this mutation, affecting only the appearance of the spider, be advantageous to its possessor?
Assuming that this trait is heritable, but exhibited only by homozygous recessive individuals, how many of the offspring of the mutant spider would display this trait if the mutant mated with a normal spider? Give both possibilities.
Would you expect natural selection to act on this trait? Explain your answer.

Bill Nye has shown that for the Florida mole cricket Scapteriscus acletus, there is considerable variation in the intensity of calls given by males, with larger individuals producing louder calls. He placed 20 males in different sizes of bucket traps and counted the number of trapped females attracted to each male one night. His data is posted outside the lab.

Calculate the selection differential for body size during this mating period.
Loudness of the cricket song correlates with body size. Can we then conclude from the answer in part (a) that natural selection will act to produce an increase in male size and hence, an increase in the intensity of the cricket's song? Why or why not?

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