KEY - Exam 2(b)-BZ220(F23)

BZ220 - E VOLUTION KEY - M IDTERM E XAM 2 (V ERSION B) F ALL 2023 ©Jennifer Neuwald (2023) – Please do not distribute or reproduce pg. 1 I NSTRUCTIONS : N AME : ___________________________________ - This exam is worth 100 points. There are 41 questions total worth various points. - Prepare your bubble sheet: include your name, student ID number, test version (you have Version B). - Please write on your exam (add you name, underline key words, scratch out wrong answers, etc.). - Choose the best answer for each question. Record your answer on the answer sheet and your exam. - Some questions require you to choose one or more correct responses for a single question. Those questions will ask you to “select all correct answers.” - Return your answer sheet to the professor. You may keep the exam questions. - A list of equations is on the final page of the exam. 1. H ONOR P LEDGE (0pt): “I will not give, receive, or use any unauthorized assistance for this exam. I pledge that this work represents my own knowledge, effort, and work.” a) True (i.e. I won’t cheat) b) False C OMPREHENSIVE : Q UESTIONS 2-7. T HE FOLLOWING QUESTIONS HAVE MULTIPLE PARTS . For the next two questions, use the word bank to choose the social interaction it describes (2pts each). 2. Bluestripe snapper fish swim together in a coordinated manner (schooling). This confuses predators, thus improving the fitness of all in the group (Price et al. 2008). [ANSWER = mutualism] 3. Threespine stickleback females attack the eggs in nests of other females of their species more often than they attack nests of blackspotted sticklebacks. This decreases the fitness of the attacked female and her offpsring, but does not increase the fitness of the attacking female (FitzGerald 1992). [ANSWER = spite] For the next two questions, use the word bank to choose the study method for hypothesis testing that best applies (2pts each). 4. Geerts et al. (2015) tested the hypothesis that Daphnia populations could adapt to increased water temperatures. They exposed Daphnia to either ambient temperature or +4 ° C and measured the CT max of the groups after 2 years. [ANSWER = experimental] 5. Cubaynes et al. (2022) tested the hypothesis that non-random mating in Canis lupus is an adaptive response to the frequency of Canine Distemper Virus. They collected data from Yellowstone wolf populations on both the frequency of disassortative vs. assortative mating as well as CDV outbreaks. [ANSWER = observational] This is a 2-part question. Complete each sentence using a term from the word bank (1pt each). Sexual dimorphism is seen in plants and animals. Based on the evidence we reviewed in class: 6. In animals, such traits are shaped by _______.[ANSWER = Sexual] 7. In plants, such traits are shaped by _______. [ANSWER = Sexual] Word Bank : a) Mutualism b) Selfishness c) Spite d) Altruism Word Bank : a) Observational b) Experimental c) Comparative Word Bank : a) Natural selection b) Sexual selection DID YOU READ THESE BEFORE STARTING THE EXAM? Plants (and anything that can reproduce sexually) can evolve under sexual selection. This was addressing a misconception. The key here is sexual dimorphism.

BZ220 - E VOLUTION KEY - M IDTERM E XAM 2 (V ERSION B) F ALL 2023 ©Jennifer Neuwald (2023) – Please do not distribute or reproduce pg. 2 M ULTIPLE C HOICE : Q UESTIONS 8-31 (3 PTS EACH ). C HOOSE THE O PTION THAT BEST ANSWERS THE QUESTION . 8. For this question, no calculations are needed. A research team from Salem has tested a population of Cucurbita pepo (pumpkins) to see if they are in Hardy-Weinberg Equilibrium (HWE) at the J-locus . They find the data listed below. From this they conclude: freq(JJ) freq(Jj) freq(jj) Observed 0.60 0.08 0.32 Expected 0.41 0.46 0.13 a) The population is in HWE, and thus, not evolving at this locus b) The population is not in HWE, and thus, not evolving at this locus. c) The population is not in HWE, and thus evolving; there are more heterozygotes observed than expected. d) The population is not in HWE, and thus evolving; there are fewer heterozygotes observed than expected. 9. If the heritability of a variable trait in a population is equal to zero (h 2 = 0), what does that mean for how that trait will evolve by natural selection: a) The trait will not evolve; the phenotypic variation is not based on genetic variation. b) The trait will evolve slowly; the contributions of the other postulates of natural selection will be reduced by the heritability. c) The trait will evolve only if the trait is a discrete trait. d) The trait will evolve as long as it results in an increased fitness of the individual with the trait. 10. When non-random mating occurs: a) Allele frequencies change, but genotype frequencies do not change. b) Genotype frequencies change, but allele frequencies do not change. c) Neither allele frequencies nor genotype frequencies change. d) Evolution occurs. 11. A dragonfly species has variation in wing pattern that ranges from transparent with very sparse patterns to wings that are so heavily marked they are nearly all black. Indvidiuals with heavy-patterned wings absorb a lot of excess heat, and so tend to overheat and die. Those individuals with nearly transparent wings do not absorb enough heat, and so tend to die from being too cold. Those dragonflies with intermediate patterning absorb an optimal amount of heat and so are successful. Which mode of selection is likely acting on wing- pattern? a) Directional b) Stabilizing c) Disruptive d) Negative frequency-dependent 12. A population of stick insects lives on an isolated island. You measure allele frequencies at a particular genetic locus with has two alleles, A and a . You determine that the frequency of the a-allele is 0.4. If you observe that the frequency of Aa heterozygotes is 0.36 in this population, what is the inbreeding coefficient? a) 0.48 b) 0.75 c) 0.25 d) 0.36 Recall the activity we did to demonstrate how genotype frequencies change (i.e., assortative e mating gives rise to more homozygotes), but that the frequency of the alleles only change if another force of evolution acts in combination with NRM See the walk-through at the end of this answer key

BZ220 - E VOLUTION KEY - M IDTERM E XAM 2 (V ERSION B) F ALL 2023 ©Jennifer Neuwald (2023) – Please do not distribute or reproduce pg. 4 18. The Centers for Disease Control (CDC) is proposing including the Influenza A strains recommended by the World Health Organization (WHO) in this year’s vaccine. A congressman objects, since similar strains were in last year’s vaccine and he is concerned about wasting the taxpayer’s money. Which of the following would best explain why the WHO strains should be included in this year’s vaccine? a) The rate of evolution for Influenza A is very high. Mutations in the antigenic sites of these strains results in our immune cells being unfamiliar with this form of the virus, and thus, cannot effectively fight infection. b) There are high levels of synonymous mutations in the non-antigenic sites of Influenza A strains, and thus, vaccines must constantly be updated to account for these new proteins. c) Vaccines can contain an infinite number of strains, and so all new strains, regardless of how likely they are to be a problem for human health, should be included in the vaccine. d) They shouldn’t! If a similar strain was in last year’s vaccine, the CDC should include a rare, new strain instead. 19. Which of the following best describes why understanding our own evolutionary history as a species can help inform medical practice? a) All of the medical problems humans suffer from today are a result of being poorly adapted to our current environment. b) Evolutionary mechanisms have worked to shape our species. Identifying which processes have influenced different traits helps develop appropriate medical strategies. c) Humans are no longer evolving due to our current environment. Therefore, our medical strategies must be based on our evolutionary history. d) The pathogens that we are subjected to are more dangerous to our species now than in the past. Therefore, knowing how we have diverged from ancestors will help evolve resistance to these pathogens. 20. Which of the following is a FALSE statement about the history of extinctions on Earth? a) There have been 5 mass extinctions in the history of earth. We are currently experiencing a 6 th mass extinction event during the Anthropocene. b) Extinction is a natural, evolutionary process. c) Background extinction rates occur at a consistent, low level throughout time. d) The rate of extinctions of vertebrates during the Cretaceous-Paleogene extinction event (which lead to the extinction of most dinosaurs) was higher than the rate of extinction we observe today. 21. Which of the following increases extinction risk the most in small populations? a) Mutation b) Purging c) Genetic Drift d) Environmental Heterogeneity 22. Which of the following is not a quality of good experimental design? a) Small sample size. b) Including control groups to test the effect of the treatment itself. c) Randomization to control for potential bias. d) Replication. Many people chose (b); Purging is when deleterious alleles are removed from the population, so that would be a GOOD thing.

BZ220 - E VOLUTION KEY - M IDTERM E XAM 2 (V ERSION B) F ALL 2023 ©Jennifer Neuwald (2023) – Please do not distribute or reproduce pg. 5 23. Shivering is a response in birds that increases endothermically generated heat in the body. Dark-eyed juncos exposed to cold temperatures for one week have an increased capacity for shivering. This allows the birds to maintain shivering for longer (and thus, stay warm longer). Based on these data, being able to adjust shivering capacity in response to temperature is an example of: a) An evolutionary constraint to living in a cold environment b) Phenotypic plasticity c) An exaptation d) An evolutionary trade-off 24. What is the Red Queen hypothesis? a) Sexual selection is driven by female choice. b) Genetic diversity is maintained by natural selection. c) Female-inherited genomes (such as mitochondrial DNA) will swamp the expression of bi-parentally inherited DNA (such as nuclear DNA). d) Organisms must constantly evolve and adapt in order to survive against ever-evolving opposing species (e.g., predators, parasites, etc.). 25. Asexual reproduction is seen more often in plants than in animals. Which of the following is an example of an asexual reproduction mechanism in animals ? a) Vegetative propagation b) Apomixis c) Parthenogenesis d) Binary fission 26. A species of mangrove trees lives in two different habitats. The coastal habitat experiences a lot of weather fluctuations and seasonal ecosystem turnover. The bay habitat is protected from weather fluctuations and has a stable ecosystem. Which of the following would be a reasonable prediction for this species: a) Coastal populations have higher sexual reproduction. Bay populations have higher asexual reproduction. b) Coastal populations have higher asexual reproduction. Bay populations have higher sexual reproduction. c) Both populations have higher asexual reproduction. d) Both populations have higher sexual reproduction. 27. Sexually-selected traits that appear to be detrimental for survival can still evolve in the population, because: a) They still have an overall positive effect on fitness, despite reduced survival. b) They are only expressed in individuals at certain times of the year (i.e., breeding season). c) They are better for the species, even if they are detrimental to the individual. d) They are continually reintroduced by mutation. 28. The figure to the right describes the relationship between number of mates and number of offspring for the two sexes. Based on this information, we can infer that: a) Males have higher fitness than females, but females have higher survival than males. b) Natural selection will not be as strong as sexual selection in either sex. c) Sexual selection will act more strongly on males. d) Sexual selection will act more strongly on females. 0 20 40 60 80 100 120 0 1 2 3 4 5 Number of Offspring Number of mates males females Many people chose (c); We have no evidence of past function for shivering being different from current function. In addition, this is asking specifically about the ability to ADJUST shivering in response to the environment. This is based on the Tangled Bank Hypothesis; The more heterogenous the environment and/or the more the environment changes, the more advantageous sexual reproduction is

BZ220 - E VOLUTION KEY - M IDTERM E XAM 2 (V ERSION B) F ALL 2023 ©Jennifer Neuwald (2023) – Please do not distribute or reproduce pg. 7 34. Disassortative mating leads to increases in homozygosity while assortative mating leads to increases in heterozygosity. a) True b) False 35. A species of dragonfly has a gene that expresses early in life as a beneficial trait that makes nymphs unpalatable (i.e., taste bad) to predators. This same gene expresses late in life as a deleterious trait that results in a brittle exoskeleton, which causes mortality. Based on the information above, is the following statement True or False: This is an example of antagonistic pleiotropy. a) True b) False 36. Bacterial pathogens can be treated with antibiotic medicines. Using antibiotics imposes strong selection pressures on the bacterial population. However, because bacteria are asexual, novel antibiotic resistant alleles that arise due to mutation spread very slowly in the population. a) True b) False 37. Because most evolutionary processes occur over long timescales while most crises in conservation are occurring in a short timescale, evolution can be used to understand the genetic history of a population, but can rarely be used to develop strategies and management plans for future conservation. a) True b) False 38. Adaptations arise to meet the needs of a species in a given environment.. a) True b) False 39. Muller’s ratchet describes the accumulation of deleterious alleles, thus leading to mutational load. This is a problem especially in asexually-reproducing species. a) True b) False 40. If sexual selection is acting on female choice in a population, the traits under section include both the male trait and female preference for that trait. a) True b) False Extra credit (3pts) - optional 41. At the end of our “Evolution of Sex” lecture, you were asked to review a news article from Harvard University about how an asexual species of weevil may be coping with changing environmental pressures despite not having the genetic variation of sexually-reproducing species. What was the main mechanism these weevils are using? a) Transposable elements b) Intermediate virus that can transfer genetic information c) Epigenetic changes d) Phenotypic plasticity in seasonal mode of reproduction This is a misconception about adaptations. Adaptations arise due to MUTATION. Selection then acts on that trait, but not because the species NEEDS it.

BZ220 - E VOLUTION KEY - M IDTERM E XAM 2 (V ERSION B) F ALL 2023 ©Jennifer Neuwald (2023) – Please do not distribute or reproduce pg. 8 ------------------------------------------ E ND OF E XAM ------------------------------------------ Formulas that you MAY need to use: p = f (AA) + ½ f (Aa) q =f (aa) + ½ f (Aa) p + q = 1 f (AA) = p 2 f (Aa) = 2pq f (aa) = q 2 f (AA) + f (Aa) + f (aa) = 1 p 2 + 2pq + q 2 = 1 R = h 2 S h 2 = Z offspring - Z population Z parents - Z population p t+1 = p t - ࠵? p t q t+1 = q t + ࠵? p t f(Aa) = 2pq (1- F ) F = 1-( f(Aa)/2pq ) rB – C > 0 E XTRA W ORKSPACE FOR M ATH P ROBLEMS , D IAGRAMMING , OR WHATEVER YOU ’ D LIKE : MATH PROBLEMS: A population of stick insects lives on an isolated island. You measure allele frequencies at a particular genetic locus with has two alleles, A and a. You determine that the frequency of the a-allele is 0.4. If you observe that the frequency of Aa heterozygotes is 0.36 in this population, what is the inbreeding coefficient? • What do we know? f(a) = 0.4 = q ; f(Aa) obs =0.36 • What are we trying to find out? F (inbreeding coefficient); F=1-(Obs/Exp) • What do we need to solve? p ; p+q=1, so p = 1-q = 1-0.4 = 0.6 • 2pq = (2)x(0.6)x(0.4) = 0.48…but this isn’t what we are trying to figure out…we still need F • F = 1-(Obs/Exp) = 1-(0.36/0.48) = 1-0.75 = 0.25 Male lions sometimes work together to take over a pride. Imagine an allele arises in a population of lions that causes brothers to help defend each other’s cubs. If a lion (L1) helps defend his brother’s cubs, his brother (L2) will have 10 additional cubs compared to what he would have without his brother’s help. However, lion L1 will have 3 fewer offspring than if he does not help. Use Hamilton’s rule to determine if such an allele would be favored (and thus, spread) in the population. (assume the brothers are full-sibs) • What do we know? B = 10; C = 3; behavior is between full-sibs (r=0.5) • What are we trying to figure out? If rB-C>0 & if thus, the allele will spread • Solve à (0.5)(10) – (3) = 2 • 2 is greater than 0, so this allele is likely to spread