Experimental tests of mate choice in nonhuman mammals: the need for an integrative approach.

Experimental studies of mate choice have normally focused on non-mammal animal species, in which female mating preferences are based on clearly defined male traits. Because mammals are invariably larger and behaviourally more complex, they are less suited to this type of experimentation. Nevertheless, numerous studies on nonhuman mammals have shown that females appear to actively choose their mates. In this Commentary, I review the current literature to reveal that most experimental tests of mate choice in mammals are unable to reveal the actual male phenotypic trait(s) of female preference, which is crucial for identifying male characteristics under sexual selection. In addition, very few studies take into account female oestrous stage, or quantify the fitness benefits to discriminating females. Future work should concentrate on demonstrating female preferences for specific male traits that are shown by genetic paternity analysis to be correlated with male reproductive success, using setups that control for the effects of male and female mating strategies and in which the actual experiments are performed during the female's peak oestrous period.