Biology Reference
In-Depth Information
which side the mouth twists to, facilitating scale-eating from one side of a host fish).
Raymond
et al
. (1996) suggest left-handedness in humans has been maintained by
frequency dependent advantage in fights; in interactive sports, which depend on fighting
ability either directly (boxing, fencing) or indirectly (tennis), there are more left-handers
in the sporting elite than expected from the population at large. However, in non-
interactive sports (gymnastics, dart, snooker, javelin) left-handers do not have an
unusual advantage.
TOPICS FOR DISCUSSION
1.
In David Harper's experiment with ducks (Fig. 5.2b), the equilibrium flock sizes occur
within a minute, before each duck has had time to visit both patches. How could ducks
reach the stable distribution so quickly? What rules could individuals use?
2.
How can the effects of predation differences between patches be incorporated into the ideal
free distribution? (see Abrahams & Dill, 1989).
3.
How would you apply the idea of economic defendability to resources other than food (e.g.
nest sites, mates)?
4.
Condition dependent tactics are more common in nature than alternative genetic
strategies. Why?
5.
Would you expect all populations of dung beetles to switch to horned males at the same
body size threshold? If not, why?
6.
How would you measure the reproductive success of the three male morphs of the ruff
(territorial, satellite, female mimic)?
7.
Another example of a 'rock-paper-scissors' game is provided by strains of the bacterium
Escherichia coli
. These strains can produce a toxin or not, and they can be resistant to a toxin
or not. Experiments by Kerr
et al
. (2002) reveal which conditions lead to the coexistence of
several strains (see also the commentary by Nowak & Sigmund, 2002). Compare these
bacterial games with the lizards we discussed in this chapter.
8.
Should we expect all animals to have personalities?
