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Evolutionary Biology Exam Study Guide, Cheat Sheet of Evolutionary biology

Evolutionary Biology Exam Study Guide

Typology: Cheat Sheet

2021/2022

Available from 06/19/2023

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BIO305 Exam 2
Instructions:
Answer using a different font (e.g., red font) so that your answers can be distinguished from the
question.
Use FULL SENTENCES in your answers, with proper spelling, grammar, punctuation, and
sentence structure. Points will be docked for improper writing style. This is a writing-enhanced
course.
Species Latin (scientific) names MUST follow proper notation or else points will be docked.
Everything must be in your own words. Plagiarized work will receive a grade of 0 and the
incident will be reported to the Academic Conduct Committee and remain on file in the Office of
the Provost. Plagiarizing more than once will result in an F in the course, with the possibility of
additional sanctions.
The maximum number of points awarded for each answer is listed for each question.
Your responses will overwrite the responses from your previous attempt at this exam. If you
leave blank any questions, your grade from your original attempt will hold. It is possible for your
grade to decrease if you score lower on your second attempt than on your original submitted
attempt.
1. As discussed in class, dark skin color in humans is thought to have been an adaptation in areas
with high levels of solar radiation because the melanin that makes skin dark prevents UV
radiation from damaging folate (involved in neural development) in the bloodstream.
Alternatively, light skin color in humans is thought to have been an adaptation in areas with low
levels of solar radiation because it allows for sufficient UV radiation to produce vitamin D within
the human body. Melanin also protects against skin cancer from UV radiation.
Why is it thought that the need for vitamins (folate and vitamin D) played a stronger role in the
evolution of skin color than did the protective effects of melanin against skin cancer? (4 points)
Folate and vitamin D play a stronger role in the evolution of skin color. Humans are exposed to
UV radiation regardless of their location on the planet and the chance of developing skin cancer
is a possibility for every human, even though skin cancer is less prevalent in people with darks
complexions. Deficiencies in folate and vitamin D is more detrimental to a population rather than
skin cancer which occur in a person’s peak reproductive years. Folate and vitamin D are strong
driving forces for the evolution of skin because it reduces offspring fitness and affect a person
overall health through their immune system and fertility. UV radiation destroy folate which is
essential for embryonic development and sperm health which may cause complications for
infertility in women. Vitamin D deficiency can cause rickets in children and osteomalacia in
adults.
2. Skin color can be measured as albedo (or reflectance), a value ranging from 0 to 1, with low
values representing dark coloration and high values representing light coloration. The
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BIO305 Exam 2

Instructions:

  • Answer using a different font (e.g., red font) so that your answers can be distinguished from the question.
  • Use FULL SENTENCES in your answers, with proper spelling, grammar, punctuation, and sentence structure. Points will be docked for improper writing style. This is a writing-enhanced course.
  • Species Latin (scientific) names MUST follow proper notation or else points will be docked.
  • Everything must be in your own words. Plagiarized work will receive a grade of 0 and the incident will be reported to the Academic Conduct Committee and remain on file in the Office of the Provost. Plagiarizing more than once will result in an F in the course, with the possibility of additional sanctions.
  • The maximum number of points awarded for each answer is listed for each question.
  • Your responses will overwrite the responses from your previous attempt at this exam. If you leave blank any questions, your grade from your original attempt will hold. It is possible for your grade to decrease if you score lower on your second attempt than on your original submitted attempt.
  1. As discussed in class, dark skin color in humans is thought to have been an adaptation in areas with high levels of solar radiation because the melanin that makes skin dark prevents UV radiation from damaging folate (involved in neural development) in the bloodstream. Alternatively, light skin color in humans is thought to have been an adaptation in areas with low levels of solar radiation because it allows for sufficient UV radiation to produce vitamin D within the human body. Melanin also protects against skin cancer from UV radiation. Why is it thought that the need for vitamins (folate and vitamin D) played a stronger role in the evolution of skin color than did the protective effects of melanin against skin cancer? (4 points)

Folate and vitamin D play a stronger role in the evolution of skin color. Humans are exposed to

UV radiation regardless of their location on the planet and the chance of developing skin cancer

is a possibility for every human, even though skin cancer is less prevalent in people with darks

complexions. Deficiencies in folate and vitamin D is more detrimental to a population rather than

skin cancer which occur in a person’s peak reproductive years. Folate and vitamin D are strong

driving forces for the evolution of skin because it reduces offspring fitness and affect a person

overall health through their immune system and fertility. UV radiation destroy folate which is

essential for embryonic development and sperm health which may cause complications for

infertility in women. Vitamin D deficiency can cause rickets in children and osteomalacia in

adults.

  1. Skin color can be measured as albedo (or reflectance), a value ranging from 0 to 1, with low values representing dark coloration and high values representing light coloration. The

measurements are taken under the arms near the arm pits, as opposed to the top of the arms or the face, to reduce the potential for environmental effects on skin albedo. At the end of class on 10/18, you were asked the following question: “What do you predict the heritability of human skin color to be? What would it look like on a graph?” a) What would be on your X and your Y axis on this graph? Clearly state how each axis would be labelled. (2 points) b) How would heritability be represented on this graph? Stated another way, what would you have to draw on the graph to show the heritability? (2 points) c) What is your prediction for the estimate of heritability for human skin color? Clearly explain what this value represents and why you made this prediction. You won’t be graded on the accuracy of your estimate, but rather on your explanation of it. (2 points) a) The x-axis would be parent albedo from 0 to 1 versus the y-axis would be offspring albedo from 0 to 1. b) The graph to best represent this heritability would be a scatterplot with a best fit line and the points of intersection would be between offspring and parent so heritability would be the slope of the line. c) My prediction for skin color heritability would be 0.8 which means that genetics plays a role on skin color variation among people as the amount of melanin individuals have vary and the MC1R gene is a important factor in skin color.

  1. Imagine that in the future scientists discover two different types of alien organisms living on another planet. One type (Type A) is rounder than the other and red, whereas the other type (Type B) is more oval shaped and blue. These organisms reproduce sexually via mating, similar to how mammals on the planet Earth reproduce. How would scientists test whether each of the following reproductive isolating barriers is operating in the speciation process between Type A and Type B? (4 points total – 1 point each) (a) premating (b) postmating-prezygotic (c) intrinsic postzygotic (d) extrinsic postzygotic (a) premating Premating: prevents mating between different species so species A and B would not be able to mate (b) postmating-prezygotic Postmating-prezygotic: The species A and species B will mate but obtain few fertilized eggs. (c) intrinsic postzygotic
  1. Describe a scenario under which asexual reproduction is beneficial to organisms (as opposed to sexual reproduction). Fully explain your answer – what is occurring in order for asexual reproduction to be more beneficial than sexual reproduction? (4 points) Asexual reproduction is preferred by bacteria, and this may be beneficial because asexual reproduction produces offspring that are identical or copies of the parents, only one parent is involved, there is no competition or cost for finding a mate and this means of reproduction saves time. For bacteria, in a safe environment with an abundance of resources, they may prefer sexual reproduction because they do not have to allocate a certain amount of energy into defending themselves against a hostile environment or finding food sources instead they can use their energy to reproduce sexually but this produces offspring with variation and would take longer to complete which is a disadvantage.