Coercion Experience Enhances Evasion Abilities in Swordtail Females

Coercive mating tactics have been observed in many different species, and are indicative of intense conflict between the sexes— when males and females differ in their reproductive goals, mating strategies which are beneficial to one sex may be detrimental to the other. One such species is the poeciliid fish Xiphophorus nigrensis; but the species' three distinct male genotypes differ in the level of sexual conflict they impose on their females. Each male type exhibits a different mating strategy — coercion, courting, or both — which in turn requires a different behavioral response from a female in order to maximize her fitness. Most notably, the coercive males’ frequent, forceful mating attempts can prove extremely costly, requiring female counter-strategy. Female poeciliids are able to reduce sexual harassment by shoaling with other females (Dadda 2015); and some studies suggest that female poeciliid brains grow larger when under strong sexual conflict pressure (Buechel et. al. 2016). In this study, we tested X. nigrensis females that were raised with coercion-only, courtship-only or both male tactics in a coercion evasion assay. Using Ethovision tracking software, we quantified these differentially reared females’ abilities to evade a coercive male. To date, no previous studies have examined the effects of courtship and coercion on female cognition and behavior directly within the same species. We found that females raised in a courtship-only environment were observed within close proximity to a small coercive male more frequently than females raised in a coercion-only environment. These data reveal important information concerning the effects that experience with each distinct mating strategy may have on female cognition and behavior.