BIOLOGY 262, PRINCIPLES OF BIOLOGY: ORGANISMIC BIOLOGY POPULATION ECOLOGY REVIEW QUESTIONS Review Questions 1. For the following life table for a single cohort of yellow perch (a fish) in a large pond fill in each provided column (see p. 962). Age in years Number Alive Survivorship Mortality Rate 0 1000 1.00 1 250 2 125 3 94 4 80 5 72 6 67 7 64 Graph the survivorship you calculated above. What type of survivorship curve is this? If you wanted the biggest "bang for your buck" when stocking perch into this pond would it be better to stock 100 newly hatched fish, 100 1-year-old fish, or 100 2-year-old fish? Why? 2. Explain how exponential and logistic population growth models differ? Sketch a quick graph of each. Which is the model that more closely approximates real systems? 3. For a population undergoing exponential growth with a starting size of 10000 and an intrinsic rate of increase of 0.5, what is the population size after 1 year? 2 years? 4. For a population undergoing exponential growth with a starting size of 5000 and an intrinsic rate of increase of 0.01, what is the population size after 1 year? 2 years? 5. Elephants and whales a have very low rmax . Fruit flies have a very high rmax . Can elephant and whale populations undergo exponential growth if there are sufficient resources and no predation (or hunting)? Graph a fruit fly and a whale population in an unlimited environment on the same graph (time = x-axis; N = y-axis). 6. For a population undergoing logistic growth with a starting size of 10000, an intrinsic rate of increase of 0.5, and a carrying capacity of 20000, what is the population size after 1 year? 2 years? 37. For a population undergoing logistic growth with a starting size of 5000, an intrinsic rate of increase of 0.01, and a carrying capacity of 20000, what is the population size after 1 year? 2 years? 3 years? 4 years? 5 years? 6 years? Graph your seven population sizes (the starting one plus the six you calculated) with years as the x-axis and N as the y-axis. Does your graph look like part of the logistic growth curve? If so, what part? 8. In a suburban area there were three patches of unmodified habitat supporting a threatened species of small lizard. A new shopping center was built destroying one of the patches of habitat (and therefore all the lizards in that patch as well. Over the period of a few years all the lizards in the other two patches that were not altered by the new shopping center disappeared. What most likely happened? How might a detailed population study of the patches before construction began have predicted that this would occur? 9. An outbreak of bubonic and pneumonic plague (caused by the bacterium Yersinia pestis) in Europe in 1347-1351 reduced the European population by one third (25 million +). Plague (Yersinia pestis) kills from 80%-95% of its sufferers quickly (killing in from a few hours to a few weeks). The 5%-20% who recover are immune. Tuberculosis (caused by the bacterium Mycobacterium tuberculosis) has also afflicted Europe in the Middle Ages but has never caused a significant reduction in population. Tuberculosis (Mycobacterium tuberculosis) kills less than 5% of its sufferers within a year, the remaining 95% do not recover but may be asymptomatic for from 2-50 years with the disease re-emerging and killing the infected person at the latest when the immune system becomes less effective in old age. Why did plague (mortality rate of infected individuals by plague 80%-95%) have a more marked effect decreasing the European population than tuberculosis (mortality rate of infected individuals by tuberculosis near 100%)? (Hint: Think about human life history and reproductive value.) 10. Explain why epidemic disease has had a much greater negative effect on human population size than warfare? (i.e., Why is the population reduction due to traditional warfare more easily overcome than those from typical epidemic diseases?) 11. A typical orange roughy fillet comes from a 15-30 year old deep sea fish captured on their spawning grounds to which each fish returns every 3-5 years. A typical cod fillet comes from a 2-10 year old shallow ocean fish that returns to its spawning grounds every year. The orange rough fishery started in the 1980s has almost collapsed with catches currently a fraction of what they were. The cod fishery off of the East Coast of the U.S. collapsed in the mid-1990s after being exploited since the 1500s. Although both fisheries collapsed due to overexploitation that resulted in very small fish populations (too small to be economically viable for harvesting), explain why the cod sustained so much more exploitation than orange roughy before
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