Contest interactions and outcomes: relative body size and aggression independently predict contest status

Social network position experiences more variable selection than weaponry in wild subpopulations of forked fungus beetles

“…Social interactions do not require direct contact in B. cornutus ; individuals reorient themselves and wave their antennae towards each other when they are within a few body lengths, suggesting chemical, acoustic and/or visual communication are important in mediating social interactions. Many social behaviours are initiated at a short distance, with individuals reorienting before beginning a combat charge or courtship approach (Mitchem, Debray, Formica, & Brodie III, 2019). Females are able to distinguish losing from winning males based on substrate borne chemical cues (Mitchem et al, in prep), suggesting information about past behavioural outcomes may transmit through network connections.…”

“…there was no 'gambit of the group'; Franks, Ruxton, & James, 2010). Previous work indicates that close physical proximity is an important determinant of individual interactions in B. cornutus (Formica et al, 2012(Formica et al, , 2017Mitchem et al, 2019). Spatial proximity is a common method for constructing social networks (e.g.…”

“…It was somewhat surprising that male weaponry did not experience more variable selection, given the behavioural scenario in which thoracic horns are used by B. cornutus. Males use their horns in physical battles with one another that influence access to courtship opportunities with females (Brown, 1980;Conner, 1988;Mitchem et al, 2019). Previous studies indicate that horn length does not influence mating success in high density subpopulations (Conner, 1989) and that the multivariate body size of social partners further favoured large body size of males through social selection (Formica et al, 2011).…”

Male competition reverses female preference for male chemical cues

“…In this study, we examined the behavior of Bolitotherus cornutus Bolitotherus cornutus are a tenebrionid beetle in which males are distinguished by the presence of elaborate horns, which they use in competition for access to females (Conner, 1988(Conner, , 1989. Usually the larger, more aggressive males with long horns win opportunities to mate and typically choose to court bigger females (Conner, 1988(Conner, , 1989Formica et al, 2016;Mitchem et al, 2019). Males are observed in male-male combat both in the presence and absence of females (Conner, 1988).…”

“…Females have an anal sternite (a hard covering on the ventral surface of the terminal abdominal segment) that acts as a lock system giving the female control over copulation (Conner, 1988), and may use chemical cues during courtship to determine whether copulation should proceed. In this system, larger males have been considered to be of higher quality with more access to females (Conner, 1988;Formica et al, 2016;Mitchem et al, 2019), but previous work done in controlled experiments suggests that females do not necessarily prefer larger males (Brown & Bartalon, 1986;Brown et al, 1985). These studies, however, took place in the absence of male competition.…”