Biology Reference
In-Depth Information
(a)
(b)
Effort of female
Effort of male
(c)
(d)
ESS
's best response
's best response
1
2
4
3
ESS
's best response
's best response
ESS
x
Effort of female
Effort of female
Fig. 8.5
Male-female conflict over how much care to provide (Houston & Davies 1985).
(a) A male's best response to the female's parental effort; (b) a female's best response
to the male's parental effort. These shallow slopes involve incomplete compensation,
so if the partner reduces its effort, the other increases but not sufficiently to compensate
for the loss. (c) Plotting both responses together shows that these lead to stable
biparental care. Imagine, for example, that the female plays effort
x
. The male's best
response is one. The female then replies with two, the male with three, the female
with four, and so on, reactions proceeding by smaller and smaller amounts until the
intersection which is the ESS. (d) If reactions have slopes steeper than one (over-
compensation) the intersection is unstable; responses proceed by larger and larger
amounts until one parent ends up doing all the work. The reader is invited to start with
any female effort and then follow the male's best response, the female's best reply, and
so on. The ESS is for uniparental care by either male or female. Which parent it is
depends on the starting point of the game.
