7. What is the male's extended phenotype,
and give an example of an experimental test of the role of the
male's extended phenotype in affecting female choice. Why is it
necessary to do such experiments?
A males extended phenotype is a characteristic outside of the
male's body that a female chooses on when deciding to mate, i.e.
territory size or quality. (3 points)
Total points for mention of an example from class and an experiment
design that emphasizes manipulations that are able to tease apart
male phenotype characteristics (i.e. male appearance or body size)
and the male's extended phenotype (i.e. territory). (14 points
- points vary on detail and explanation)
Ex. Females might choose males on the basis of the quality of
the male or the quality of the territory that the male secures.
Howard (1979) demonstrated that male bull frogs tend to mate with
the largest male bull frogs and their is a positive relationship
between male bull frog size and the number of females that a male
secures as mates. Howard assessed the quality of the male and
the male's territory, by tracking the survival of the eggs through
to hatching as a tadpole. Such aspects of territory quality
can be considered part of the male's extended phenotype.
Another example would be shrikes and lizards jewelry.
Cause and Effect is the key -- answering cause and effect.
A female can choose a male on the basis of a number of potential
traits, and such male traits might indeed be correlated with one
another or indeed, correlated with the female preference per se.
It is essential to perform manipulative experiments of the male
trait to isolate the effect of a specific male trait on the preferences
of females. (3 points)