Male mating success and risk of predation in a wolf

0[ Traits that bene_t males through sexual selection are simultaneously expected to impair males by provoking costs through natural selection[ If we consider the two male _tness components\ mating success and viability\ then we may expect that the increase in male mating success resulting from a larger trait size will be counter! balanced by an increase in viability costs[ 1[ We studied the bene_ts and costs of male mate searching and sexual signalling activity in the wolf spider Hygrolycosa rubrofasciata[ In the _eld\ males search females actively and court them by drumming dry leaves with their abdomen[ Females have been shown to prefer males with high drumming rate[ Male moving and especially drumming is energetically highly demanding and drumming results in signi_cant mortality costs[ 2[ Our objective in this study was to determine whether male mate!searching activity or drumming activity a}ect male mating success and the risk of males being predated[ 3[ It was evident that both higher mate!searching activity and higher drumming activity bene_ted males by increasing their mating success[ Higher mate!searching activity clearly impaired males by causing direct increase in predation risk[ There was also a slight tendency that more actively drumming males had higher risk of predation and from all of the predated males 02[2) were caught directly after they had drum! med[ Furthermore\ male drumming activity decreased drastically in the presence of the predator[ 4[ We conclude that in H[ rubrofasciata both increased mate!searching activity and drumming activity bene_t males through sexual selection\ but at the same time natural selection provokes direct balancing costs on the same traits[