Biology Reference
In-Depth Information
(a)
1.0
0.5
50
100
Time (min)
spent in copula with female
B
(b)
1.0
Predicted
0.5
Observed
A
156.5
50
100
Search and guard time
S
= 156.5 min
Time (min)
spent in copula with female
Fig. B3.1.1
(a) The proportion of eggs fertilized by a male dung fly (
Scatophaga
stercoraria
) as a function of copulation time: results from sperm competition experiments.
(b) The predicted optimal copulation time (that which maximizes the proportion of eggs
fertilized per minute), given the shape of the fertilization curve and the fact that it takes
156 min to search for and guard a female, is 41 min. The optimal time is found by drawing
the line AB. The observed average copulation time, 36 min, is close to the predicted value
(Parker, 1970a; Parker & Stuart, 1976) (photo of a pair of dung flies © Leigh Simmons).
