full text - Caspar Bgsu - Bowling Green State University

2. Evolutionary Aspects of Aggression: The Importance of Sexual Selection 17
0.8
log(male/female weight) contrasts
-1.5
0.4
0.0
-1.0 -0.5 0.0 0.5 1.0 1.5
-0.4
-0.8
log(harem size) contrasts
Figure 2.3. Regression line through the origin on harem size and body weight dimorphism. The data
points are from a phylogenetic independent contrasts analysis. There is a significant
relationship between harem size and sexual size dimorphism (b¼0.376, p¼0.000,
R 2 ¼0.577, n¼36) (from Lindenfors et al., 2002).
extant species (Table 2.1). Systematists recognize 26 monophyletic mammalian
orders (Wilson and Reeder (1993)). When investigating each order separately,
the majority of orders also turned out to be significantly male-biased dimorphic
(average male/female mass ratio >1.0 and p