Impact of social context on mating behavior and sperm competition in the western mosquitofish

• In Event: Systematics and Evolutionary Biology Oral Session & Section Meeting

Abstract

The western mosquitofish (Gambusia affinis) is a live bearing species of fish with males that employ a coercive mating system and force copulation with females. In this study we sought to determine whether the social environment of males affects sperm expenditure and mating behaviors. We placed focal males into various social settings, including a control with no stimulus, female stimulus only, and two competition treatments containing a female and either one or two males. Males remained in the treatments for seven days, and sperm samples were collected on days four and seven with behaviors observed on day four prior to sperm collections. We hypothesized that social environment would affect mating behaviors and sperm expenditure in this species. Our initial prediction was that males exposed to competitors would display fewer mating behaviors, but more gonopodial displays and higher sperm expenditure. Conversely, males that had been isolated or exposed only to females would mate more frequently but would have lower sperm expenditure and fewer gonopodial displays. To date, data indicates that the social environment of male G. affinis does not influence mating attempts or frequency of gonopodial displays. Analysis of sperm data revealed that there was a significant impact of social environment on the sperm count collected from males on day seven (p = .003). However, this difference was not significant on day four or for the change between days. More detailed analysis is in progress and full findings of both behavioral and sperm data will be presented at the meeting.

Authors

• Amber Raven, St. Edward's University

• Raelynn Deaton Haynes, St. Edward's University