Sexual conflict and the evolution of female mate choice and male social dominance

Abstract

Con£icts between the sexes over control of reproduction are thought to lead to a cost of sexual selection through the evolution of male traits that manipulate female reproductive physiology and behaviour, and female traits that resist this manipulation. Although studies have begun to document negative ¢tness e¡ects of sexual con£ict, studies showing the expected association between sexual con£ict and the speci¢c behavioural mechanisms of sexual selection are lacking. Here we experimentally manipulated the opportunity for sexual con£ict in the cockroach Nauphoeta cinerea and showed that, for this species, odour cues in the social environment in£uence the behavioural strategies and ¢tness of males and females during sexual selection. Females provided with the opportunity for discriminating between males but not necessarily mating with preferred males produced fewer male o¡spring than females mated at random. The number of female o¡spring produced was not a¡ected, nor was the viability of the o¡spring. Experimental modi¢cation of the composition of the males' pheromone showed that the fecundity e¡ects were caused by exposure to the pheromone component that makes males attractive to females but also makes males less likely to be dominant. Female mate choice therefore carries a demographic cost but functions to avoid male manipulation and aggression. Male^male competition appears to function to circumvent mate choice rather than directly manipulating females, as the mate choice can be cryptic. The dynamic struggle between the sexes for control of mating opportunities and outcomes in N. cinerea therefore reveals a unique role for sexual con£ict in the evolution of the behavioural components of sexual selection.

The human brain is a detector of chemosensorily transmitted HLA-class I-similarity in same- and opposite-sex relations

“…Furthermore, the reduced fitness in inbred mice is related to the reduced survivorship of males in competitive conditions (Meagher et al 2000). Thus, male competitive behaviour could have evolved secondary to female mate choice (Moore et al 2001) on the basis of the same MHC-related regulatory mechanisms.…”

“…heterozygote and rare allele advantage, inbreeding avoidance; reviewed by Eklund 1994 andPenn &Potts 1999). However, while sexual selection is traditionally considered to include inter-and intrasexual components (Moshkin et al 2000;Moore et al 2001;Olsson et al 2003), it has not been shown whether the MHC also contributes to male competitive behaviour.…”

Male–female conflict and genitalia: failure to confirm predictions in insects and spiders

“…Some evolutionary phenomena that were previously explained by mate choice may be better explained by coevolution of males and females resulting from conflicts of interest between the sexes over control of copulation and fertilization (Parker, 1979;Chapman et al, 1995Chapman et al, , 2003Rice, 1996;Alexander, Marshall & Cooley, 1997;Holland & Rice, 1998Rice & HoUand, 1999;Johnstone & Keller, 2000;Michiels, 1998;Gavrilets, Arnqvist & Friberg, 2001;Pitnick, Brown & Miller, 2001 a;Pitnick, Reagan & Holland, 2001 ¿;Stutt & Siva-Jothy, 2001; Moore et al, 2001). These recent discussions emphasize one particular class of direct benefits that a female could derive from resisting male sexual behaviour: avoidance of male-inflicted reductions in her ability to produce offspring.…”

Protein and carbohydrate intake influence sperm number and fertility in male cockroaches, but not sperm viability

“…Most males are able to produce a spermatophylax that exceeds this threshold and therefore typically avoid sperm competition when mating with a virgin female [42]. Sperm competition is not completely eliminated by this mechanism, however, as females can remate after the parturition of their first clutch [40,41] and can store sperm for their entire lifespan [41,42]. There is already compelling evidence that sperm production is costly in N. cinerea.…”

“…Male N. cinerea produce a complex ejaculate (the spermatophore) consisting of sperm enclosed in a membranous sac (the ampulla) that is embedded in a gelatinous, proteinaceous mass (the spermatophylax) [40]. If the spermatophylax is above a threshold size, it stimulates a stretch receptor in the female bursa copulatrix that inhibits remating behaviour [35,41,42]. Most males are able to produce a spermatophylax that exceeds this threshold and therefore typically avoid sperm competition when mating with a virgin female [42].…”