This question is to check that you are physically in the room. If you are not in the classroom (or in an approved proctoring center) immediately shut the exam down and contact your instructor. You must get this question correct for your exam to be graded. If you are in a proctoring center skip this question.  What is the two word secret code shared in the room? 

Part 4 – Short Essay Questions. Answer only 2 of the 3 following questions. If you answer all 3, only the first 2 questions will be graded.

A researcher is studying the interaction between a bird species and a small mite species that lives on the bird’s feathers. The mites feed on the bird’s blood, causing the bird to lose feathers and expend more energy maintaining its health. The mites benefit from feeding on the bird, but the bird’s health declines as a result of the interaction. Based on this information, which of the following types of interactions best describes this relationship?

In a soil environment, two species of bacteria, Bacterium A and Bacterium B, live in close proximity. Bacterium A is capable of breaking down complex organic molecules in the soil into simpler compounds. Bacterium B cannot break down these complex molecules on its own, but it benefits by absorbing the simpler compounds released by Bacterium A. Bacterium A, however, is unaffected by the presence of Bacterium B and continues its metabolic activity as usual. Which of the following terms best describes the interaction between Bacterium A and Bacterium B?

A) A vampire bat shares food with a sibling who is starving, increasing the sibling’s survival chance by 40%. The cost to the donor is a 10% reduction in its own survival. The donor and recipient are full siblings (i.e. they share the same mother and father). Does this food-sharing behavior satisfy Hamilton’s Rule, and is it likely to be favored? (Need to show calculations to receive full credit) B) Now consider a scenario where the same bat is sharing food with a starving grandparent, increasing the grandparent’s survival chance by 40%. The cost to the donor remains a 10% reduction in its own survival. The relatedness coefficient between the donor and grandparent is r=0.25. Does this food-sharing behavior satisfy Hamilton’s Rule, and is it likely to be favored? (Need to show calculations to receive full credit)

You are given the following data on population densities for two herbivores, Species X and Species Y, in an experimental plot with varying abundances of the same plant species: Plant Abundance (biomass) Species X Density (ind/km²) Species Y Density (ind/km²) Low 5 15 Medium 10 20 High 18 10 A. Based on the data, what might be a reason for the decrease in Species Y density at high plant abundance? B. What ecological concept could explain the contrasting densities of Species X and Y at high plant abundance?

Equations discussed in Chapters 54 – 57: * = multiplication sign dn/dt = B – D dn/dt = b*N – d*N r = (b-d) dn/dt = r*N dn/dt = r*N * ((K-N)/K) Ro = sum (lx * mx) Nt = No * Rot r*B > C Ppersist = 1−E+(M*(1−E)) Pregional = 1−(Pextinct A * Pextinct B * Pextinct C * Pextinct D) Where Pextinct = 1−Ppersist lx = nx/no Nt+1 = Nt*Ro Nt = No*Rot

Two species of lizards living on the same island have similar diets and body sizes. Over time, one species evolves longer limbs, allowing it to capture different prey. This is an example of:

Which of the following traits is most characteristic of an r-selected population?

A desert plant species blooms only after a significant rainfall event. When enough water is absorbed by its roots, a hormonal signal triggers the plant to flower and reproduce. Is the hormone-induced flowering a proximate or ultimate cause of behavior?