Does the winner-loser effect determine male mating success?

Area of Science:

• Behavioral Ecology
• Animal Behavior
• Evolutionary Biology

Background:

• The winner-loser effect describes how prior contest outcomes influence future success.
• This effect is well-documented in competitive interactions.
• Its impact on reproductive success, particularly mating behavior, remains less understood.

Purpose of the Study:

• To investigate if winning or losing fights influences male mosquitofish mating success.
• To determine if the winner-loser effect extends to reproductive behavior in *Gambusia holbrooki*.

Main Methods:

• Male mosquitofish (*Gambusia holbrooki*) engaged in staged fights, establishing 'winner' and 'loser' groups.
• Size-matched winners and losers were paired with a female in a trio setting.
• Male-female association time and copulation attempts (successful and unsuccessful) were recorded.

Main Results:

• Males who won previous fights spent significantly more time associating with females.
• Winning or losing did not affect the number of copulation attempts or success rate.
• Male size impacted mating success differently: larger losers had fewer successful copulations, while size did not affect winners.

Conclusions:

• The winner-loser effect influences pre-copulatory mating behavior (female association) in male mosquitofish.
• While winning may increase mating opportunities, it does not directly enhance copulation success in this species.
• The interaction between dominance status and body size affects reproductive success, with larger losers being disproportionately disadvantaged.