Practice_final

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University of British Columbia *

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230

Subject

Biology

Date

Dec 6, 2023

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pdf

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Uploaded by zhifanwang

Practice final from last term • You will get a good idea of the topics that could come up (though climate change was not covered). • It is a good, though not perfect, representation of the styles of questions you could be asked. I say not perfect, because I did not write most of these myself. It was also designed for an open-book online format. This means we assume students could look up answers to anything, so there were no rote memorization questions (e.g., “Define ______”). It also means there was no opportunity to draw. • In general, I include more short answer questions on my final exams and far fewer multiple choice. 1. What characterizes a Darwinian demon (i.e., a species that is not limited by life-history trade offs when maximizing its fitness)? a) High birth rate, high death rate b) Low birth rate, high death rate c) Low birth rate, low death rate d) High birth rate, low death rate 2. Under life-history trade-offs, we expect that as birth rate increases, survival rate… a) Increases b) Decreases c) Stays the same 3. Compared to a K-selected species, an r-selected species is bad at… a) Converting abundant resources into offspring b) Having high birth rates c) Dispersing d) Surviving to reproductive age e) Recovering from disturbance 4. Naked mole rats live in high densities underground. You did an experiment to test whether the density of naked mole rats that survive to reproduce varied with initial density of mole rats in the experiment. Below are the data that you observed. Which statement best describes the result? a) The percent of rats surviving was about the same in plots with 100 rats initially vs 1000 rats initially. b) The percent of rats surviving decreases as the initial density increases. c) The percent of rats surviving was highest at the initial density of 1000 rats. d) The percent of rats surviving increases as initial density increases. 5. Based on the information in the previous question, what is not a plausible explanation for the effect of density on percent survival that you observed? Choose all that apply. a) Disease (we didn’t talk too much about this one, but in general, diseases spread more quickly through large populations) b) Resource partitioning c) Facilitation d) Resource competition e) Disturbance

6. Based on the graph in Q4, are you able to conclude that population growth rates increase or decrease with density? Explain your reasoning in max two sentences. 7. A population of pygmy possums has a current population size of 1,000 individuals. The species does not experience density-dependent or inverse density-dependent growth. If r = -0.1, what will the population size be at t = 10? Round to the nearest whole number. 8. Based on the information in the previous question, what are the possible explanations for the pygmy population’s dynamics over the last 10 years? Choose all that apply. a) The population was above its minimum viable population size b) Allee effects c) Environmental conditions changed from being suitable to unsuitable d) Environmental conditions changed from being unsuitable to suitable e) The population was above its carrying capacity 9. Based on the left-hand graph, which graph on the right correctly represents changes in dN/dt with increasing N? Hint: think derivatives! dN/dt is not the same as r a) A b) B c) C d) D 10. The hint to the previous question states that dN/dt is not the same as r. How does it differ from r, and why is r more informative about population dynamics? Answer in two sentences max. (cont’d on next page)

11. Your research team has been studying the population dynamics of invasive seagrass Zostera japonica (N 1 , dashed line) and native seagrass Zostera marina (N 2 , intentionally left out of this figure) in estuaries. Use the below graph to answer questions a-c. a) What is the carrying capacity of Z. japonica (species 1)? b) What is the competition coefficient of Z. marina on Z. japonica (alpha)? c) What is the outcome of competition? Explain how you reached this conclusion. 12. Researchers studied population dynamics of Zostera marina and Zostera japonica in outer coast habitats in BC (different from previous habitat). Estuaries have lower salinity and lower current compared to the outer coast. Researchers measured carrying capacity and measured the competition coefficients for both species, producing this figure. 13. What are the equilibrium population sizes for Z. japonica and marina based on this figure? (cont’d on next page)

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