Final Exam                                                                                                                         Evolution 2022

Name:75 points

Directions: Please read all directions and questions carefully.Make sure to answer all parts of eachquestion.You can use your book, scientific literature, and lecture presentations. You may also use the R code for understanding population genetics and creating figures and any materials that have been posted at Brightspace.You may also use the internet; however, relying solely on non-primary sourcescan be risky – you can do so, but at your own peril. Please upload this Word document (.docx) in Brightspace (course content > assignments > final exam) by Saturday, April 30^that 2pm. Late assignments will be penalized 10 points per day until 7 days past due, at which point they will be assigned a 0. Please see syllabus for discussion of plagiarism and other relevant details. Please space out questions as needed. Lastly, remember you are not to discuss your questions or answers with anybody currently (or previously) taking this class (this is an independent assignment).Any instances of collaboration will result in a score of 0 points on both exams; this is a solo assignment. You may reach out to Morgan or myself with questions (especially for clarification). Thank you for an awesome semester – you were a great class, and I very much appreciated your insights and participation!

Section 1 (25 points): Population genetics; 5 questions. (Lectures 1-10).

Section 2 (25 points): Rapid evolution through bioinformatics; 1 question. (Lectures 11-15).

Section 3 (25 points):Speciation through phenotypic evolution; 5 questions (Lectures 15+).

Section 1 (25 points):

Question 1: Fill in the blanks (4 pts) – options include “increases”, “decreases”, or “does not change”.

1. Genetic drift _____decreases_______________ genetic diversity within populations and ___increases_____________ genetic differentiation between populations.

• Directional selection  ______decreases______________ genetic diversity within populations and _____decreases___________ genetic differentiation between populations.

• Mutation  _________increases___________ genetic diversity within populations and _________increases_______ genetic differentiation between populations.

• Gene flow  ____increases________________ genetic diversity within populations and ______decreases (due to homogenizing)__________ genetic differentiation between populations.

Question 2:What mechanisms could create two populations to have an F_ST value of 0.99? Name and describe at least 3 mechanisms (5 points):

Question 3: Fill in the blanks (6 pts) –the three requirements for a response to selection are:

1. Variation in Phenotype____________________________________________________
2. The phenotype must be heritable____________________________________________
3. Differences in fitness between individuals with different phenotype ________________

Question 4: (10 pts) In southwest Arizona there is a large, isolated population of kangaroo rats with over 1000 individuals and a 50:50 sex ratio. You genotype these kangaroo rats at 10 SNPs. You start this genotyping project in the year 2020. In year 2050, the population undergoes a large population decline to 10 individuals and stays around 10 individuals until the year 2100, at which point you retire (at a very old age). Draw a plot illustrating the allele frequencies of all 10 loci from year 2020 to year 2100. Label all axes clearly!

Now draw a second plot similar to that in the question above, except that in the year 2050 the population does not decline, but instead responds to a new selective pressure in the form of a novel disease spreading into the population. The disease is a strong agent of selection and results in considerable mortality. Importantly, 5 of the loci are neutral and the other 5 are linked to genes that play a role in disease resistance. Explain your plots.

Section 2 (25 points):

Question 4 (25 points) short essay: The domestication of wolves (Canis lupis) into dogs (Canis lupis; sometimes Canis lupis familiaris) occurred approximately 10,000 years ago. Describe how this process occurred from a genetic, phenotypic, and population-genetic standpoint. Specifically, what genes were involved (5 pts), what traits were selected (5 pts), what roles did gene flow and mutation play (10 points), and what were/are the consequences of inbreeding (5pts). Please cite references, preferably from primary literature. 

Section 3 (25 points):

Question 5 (5 points): Four different modes of speciation are…… (name and describe mechanism):

1-Allopatric speciation: Speciation by genetic divergence of populations occupying different and separate geographic regions.

2-Sympatric speciation:Speciation by genetic divergence of populations occupying the same geographic regions.

3-Parapatric speciation:Neighboring populations diverge while they continue to interbreed.

4-Peripatric speciation:Peripatric speciation is a special version of the allopatric speciation mode and happens when one of the isolated populations has very few individuals.

Question 6 (5 points):Prezygotic barriers to reproduction are more likely to facilitate speciation than postzygotic barriers (True or False: Defend your position)

False.

A prezygotic reproductive barrier is a mechanism that prevents fertilization from occurring. Apostzygotic reproductive barrier is a mechanism that reduces the viability or reproductive capacity of hybrid offspring.

Question 7 (5 points): Describe in detail several mechanisms by which sympatric speciation can occur (1 point for each mechanism).

Question 8 (10 points): Define demographic, genetic, and evolutionary rescue (1 pt. each). Imagine you are in charge of managing a declining Pacific salmon population. Describe a situation where each form of rescue (i.e., demographic, genetic, evolutionary) would be most appropriate (3 examples, 2 pts each). Which form of rescue is the least labor intensive (explain your choice; 1pt).