Sexual responsiveness is condition-dependent in female guppies, but preference functions are not

Variation in mate choice behaviour among females within a population may influence the strength and form of sexual selection, yet the basis for any such variation is still poorly understood. Condition-dependence may be an important source of variation in female sexual responsiveness and in the preference functions for male display traits that she expresses when choosing. We manipulated food intake of female guppies (Poecilia reticulata), and examined the effect on several measures of condition and various components of mate choice behaviour.

Diet significantly influenced four measures of female condition: standard length, weight, reproductive status and somatic fat reserves. Diet also significantly affected female sexual responsiveness, but not preference functions: females in good and poor condition prefer the same males.

Variation in female condition within populations is therefore unlikely to influence the direction of sexual selection imposed by female choice. It may, however, influence the strength of sexual selection due to its effects on female responsiveness. The relative importance of female choice as a sexually selective force may also covary with female condition, however, because low responsiveness may result in sneak copulations being relatively more important as a determinant of the paternity of offspring. Differences among populations in mean condition may also influence geographic differences in the strength of sexual selection.