Female mate choice in the domesticated goat (Capra hircus): Current understandings and implications

Female mate choice is the tendency for females to distinguish among and mate selectively with one specific phenotype. In promiscuous species in which males contribute genes only, females should mate with higher quality males. This propensity accounts for the display of dimorphic characteristics that cannot be explained through Darwin's theory of natural selection. Female mate choice has not been studied in domesticated species like the goat, in part due to single-male breeding programs and the use of artificial insemination which inhibit the opportunity for mate choice. However, existence of mate choice in a domesticated species would suggest that the underlying mechanisms of mate choice are robust. Results from a series of experiments support the concept of mate choice in domestic animals. Female goats are able to distinguish among and show preference for males with higher testosterone (T) concentrations. Females may use a suite of T-dependent physiological and behavioral cues that increase in frequency and intensity during the breeding season to assess potential mates, specifically courtship and chemical cues. Behavior studies indicate that morphological cues are not used to distinguish among males. Instead, males that display intense chemical and/or courtship cues are preferred by estrous females. Analysis of T concentrations reveals that males with higher T concentrations have more intense chemical cues and higher courtship rates than those with lower T concentrations. High testosterone concentrations appear to impose high energetic costs as males with high T concentrations lose more body weight during breeding season, likely due to the increased frequency of T-dependent physiological and behavioral cues. Testosterone concentrations and resulting T-dependent behaviors may serve as an honest indicator of a male's overall fitness.