The Elements of Evolution (46-8) Sexual Selection Intensity

Sexual Selection Intensity

In many animals, male reproductive success is more dependent upon competitive mating pressure than it is for females. Hence, sexual selection commonly acts with greater intensity on males than females. The result shows itself in a syndrome of traits, including behaviors.

In courtship, males commonly expend more time and energy, and take greater risks. Males generally court and attempt copulation with a wider range of partners than females. Males are more likely to resort to violence against sexual rivals and to force copulations upon resist-ing partners.

The sexual selection syndrome also includes life-history variables. Because of the sexual competition they face, males take longer to attain sexual maturity. Males tend to have a higher mortality owing to sexual competi-tion.

Then there are the morphological traits: anatomical specializations for aggression, including horns, antlers, enlarged canine teeth, and larger bodies than are ecologi-cally optimal. Males commonly sport more spectacular sexual advertisements, both visual (elaborate and brightly colored adornments) and tactile (complex genitalia).