full text - Caspar Bgsu - Bowling Green State University

2. Evolutionary Aspects of Aggression: The Importance of Sexual Selection 15
the benefit of winning—the value of the contested item—is much larger than the
cost of losing. If the choice is reproduction or death, fights become deadly. This is
why fights among elephant seals are so fierce and bloody. The chance to mate
occurs only once per year and most males never even get close. For the successful
males it is another story—in a study of Southern elephant seals, harem holders
accounted for 89.6% of the recorded paternities (Fabiani et al., 2004; Fig. 2.2).
The sequential assessment game is a variant of a game theoretical setup
termed the “hawk-dove game” (see also Chapter 3). In this game, there are two
possible strategies: always fight (“hawk”) and always yield (“dove”), where it is
assumed that the two competitors have equal fighting ability. An Evolutionarily
Number of males Number of males
12
8
4
0
12
8
4
RUB96
SF96
SF97
0 1 2 7 0 1 12 1 24
SI196 SI296 SI297
0
0 1 24 0 1 2 8 21 0
12
1 2 8 32
Number of males
8
4
SM96
HH
NHH
0
0 2 12
Number of paternities
Figure 2.2. Number of paternities achieved by the harem holder (HH) and the other males (NHM)
associated with each harem in seven different populations of Southern elephant seals
(from Fabiani et al., 2004).