Unformatted text preview: PCB 4043: Homework #7 This HW is intended to help you grapple with the math that we have been doing in lecture. Provide a short answer. You’ll need to answer portions of the HW by using Excel. This exercise will also prepare you for the lab on Sea Turtle dynamics. If you can do this homework, you’ll be well prepared to crank through that lab also. You are studying a species of endangered birds; and you have been studying one of the last remaining populations of these birds. This bird reproduces each spring. Each summer you tag each new fledging and record the fate of older birds. Based upon the data you’ve collected, you have parameterized a stage‐structured demographic model. You construct the following life cycle diagram. 0.1
0.3 0.5 Small Large Medium 0.3
0.6 0.5 Newborns 10 1. What fraction of the birds in the “small” class die each year? 2. Which group has the higher annual survival? 3. Which group has the lowest annual survival? 4. Which group(s) can reproduce? 5. Project the size of this population one time step into the future if this past summer (call this time 0) you counted 20, 10, 10, 10 individuals in the four classes (from Newborn to Large). Do this “by hand”. What are the new numbers of Newborns, Small, Medium and Large birds (i.e., at time 1)? 6. Now do this projection in Excel and extend it for 40 years (the hard part is doing this for the first year – then you can just have Excel repeat the process for the other 39 steps). Check the first year and make sure Excel got the same answer you got doing it by hand. If you’ve set up the Excel file incorrectly, now’s the time to figure it out. Please do not worry about having “fractions” of individuals (e.g., 3.33 birds) – that’s okay with me. 7. What is the predicted population growth rate (Nt+1/Nt) for each annual increment? 8. Is the population growing, declining or staying the same? 9. Does the growth rate change in a consistent way? Why? What happens to the age structure over this 40 year period? ...
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- Spring '11
- life cycle diagram, predicted population growth, Sea Turtle dynamics., annual survival, lowest annual survival, higher annual survival