This review addresses current issues in the study of mating systems and
mate choice and shows how sexual selection results in trade-offs for both
Arbitrary female preferences serve as a null hypothesis for comparison
with the alternative hypotheses of direct and indirect net benefits for
Indirect benefits require heritable male traits and thus raise the issue
of decreasing additive genetic variance which could put female choice out
Accelerating evolution of preferences and traits can result from at least
two mechanisms, but genetic correlation and the consequent possibility for
accelerating evolution will develop whenever heritable preferences and
traits affect mating.
An expanded view of mate choice includes indirect as well as direct
choice. As a result, the coevolution of male and female traits is seen to
have much greater scope than currently appreciated.
The evolution of exaggerated traits and reliable signaling systems for
female assessment results from an optimization of fitness (survival X
reproduction) in males and an optimization of decision-making in noisy
conditions by females.
Discordances between preferences and traits in a population can result
from phylogenetic constraints or from current selection on preferences and
This review thus emphasizes that the evolution of exaggerated traits and
preferences is affected by inevitable trade-offs for the individuals