Midterm1-2004-Fall-KEY

Midterm1-2004-Fall-KEY - Name KEY Page 1 of 10...

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Name: KEY Page 1 of 10 Instructions: --Write your name on all the pages --Make sure that all 10 pages are attached. --You may not use calculators or other electronic aids. The math needed to solve a problem should be relatively simple. If you can't do the math, just show what needs to be calculated (e.g., "answer = .5 x .3") --If you get hung up on a problem, skip it; return to it after you’ve answered the “easy” problems. GENERAL ECOLOGY PCB 4044 FALL 2004 MIDTERM I PAGE POINTS POSSIBLE SCORE 2 16 __ JSW ___ 3 13 __ MC ___ 4 12 __ MC ___ 5 7 __ MC ___ 6 12 __ MC ___ 7 6 __ CWO ___ 8 14 __ CWO ___ 9 10 __ CWO ___ 10 10 __ JSW ___ _____ _________ TOTAL 100 _____
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Name: KEY Page 2 of 10 2-1. An herbivorous insect (known as Species X ) occurs on several islands off the coast of Florida, but is absent from the mainland. Two others species show the opposite pattern: an insectivorous bird and a close relative of the insect (also an herbivorous insect) occur only on the mainland (but not on the islands). You know nothing else about the system a) (6 points) List two hypotheses that might explain the absence of Species X from the mainland (each hypothesis should emphasize a different process). There were man y options, such as: Predation from the birds species limits X's distribution Competition from the close relative prevents X from persisting on the mainland The insect has limited dispersal ability and cannot disperse to the mainland (but could make it there if it did) – of course, this ignores the issue of why X is limited to the islands now. A variety of other hypotheses could be given relying on information not in the problem (e.g. ., X feeds on a plant that is restricted to the islands – the host plant does not occur on the mainland). 2-2. (10 points) For each of the following, explain why it is an essential element of a well designed experiment. Replication No two units (individuals, cages, petri dishes, incubators, etc.) are identical. Replication is needed to quantify the amount of variation expected between units that are subjected to the same treatment, and is therefore need to gauge the importance of any observed difference between two different groups ((i.e., the mean of the two groups will differ due to inherent variation among units – replication provides an estimate of this variation). Controls Controls provide a baseline of comparison; a control contains all factors as another treatment except the factor of interest (a control is not "do nothing"). Thus, a control is a treatment group that allows the investigator to isolate the effect of interest: e.g., the administration of a drug can cause improvement of health via a psychological effect resulting from the patients expectation of improvements – hence a placebo is usually administered to a control group to remove this effect and isolate the effect of the drug.
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Name: KEY Page 3 of 10 3-1. (6 points) A population grows according to the standard logistic equation (without time lags). At very low densities (close to zero), the per capita growth rate is 0.40 / year. At a density of 70, the per capita growth rate is zero.
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This note was uploaded on 06/04/2011 for the course PCB 4043 taught by Professor Osenberg during the Spring '10 term at University of Florida.

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Midterm1-2004-Fall-KEY - Name KEY Page 1 of 10...

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