Problem 1
The northern spread of the African honey bee in North America has slowed in recent years. Discuss how you might find out the reasons for this slowdown, and how you might find out how far it might spread to the north.
Problem 3
Discuss the problem of defining exactly the "geographic distribution" of a plant or animal. Gaston (1991) reviews this problem.
Problem 5
In discussing Liebig's Law of the Minimum, Colinvaux \((1973, \mathrm{p} .278)\) states: The idea of critically limiting physical factors may serve only to obstruct a theoretical ecologist in his quest for a true understanding of nature. ... . To say that animals live where their tolerances let them live has an uninteresting sound to it. It implies that animals have been designed by some arbitrary engineer according to some preconceived sets of tolerances, and that they then have to make do with whatever places on the face of the earth will provide enough of the required factors. Evaluate this critique.
Problem 6
Butterflies in Europe and North America have been extending their range to the north in recent years. Discuss at least three hypotheses that could possibly explain this range extension and indicate what data you would like to have to test these hypotheses.
