Fighting isn’t sexy in lekking Greater Sage-grouse: A relational event model approach for mating interactions

The relationship between aggression and mate choice in mating systems is
critical for understanding the evolution and diversification of sexual
organisms, and yet remains the subject of vigorous debate. A key challenge
is that traditional correlational approaches cannot distinguish underlying
mechanisms of social interaction and can indicate misleading positive
associations between aggression and mating events. We implement a novel
Relational Event Model (REM) incorporating temporal dependencies of events
in a social network to study natural reproductive behavior in a
lek-breeding system where males gather to display and females visit to
evaluate mates, often observing both male courtship displays and fights.
We find that fighting is not attractive to females. Indeed, males are less
likely to start and more likely to leave fights with females present,
plausibly to avoid entanglement in protracted combat cycles arising from
emergent social processes that reduce availability to mate. However,
fighting serves other roles, e.g., to deter copulation interruptions and
rebuff competitors. Our findings support the hypothesis that social
systems regulating conflict and promoting females’ choice based on display
are fundamental to stable lek evolution. Moreover, our analysis highlights
the utility of the REM framework in testing mechanistic hypotheses in
behavioral ecology and evolution.