ENERGETIC COSTS OF MATE GUARDING BEHAVIOR IN MALE STREAM-DWELLING ISOPODS

In the stream-dwelling isopod Lirceus fontinalis, mates and females en gage in a precopulatory mate guarding phase prior to mating. We examin ed the energetic costs of mate guarding behavior in males by separatel y assaying glycogen and lipid content at different time increments fol lowing mating. We found that males that had recently mated possessed r educed glycogen reserves and that these reserves were fully replenishe d within 36 h. Conversely, we found that male lipid reserves were unaf fected by time since mating. We concluded that precopulatory mate guar ding behavior is energetically costly to males and that glycogen is th e energy source utilized to pay that cost. We also examined whether fo od deprivation during the mate guarding phase affected male energy res erves (glycogen) at the end of that phase, We found that males that we re held in the laboratory and starved during mate guarding possessed r educed glycogen at the termination of the phase when compared to fed m ales. This reduced quantity was equivalent to the glycogen reserves of recently mated males collected from the field. We propose that food d eprivation during the mate guarding phase explains the reduction in gl ycogen reserves at the termination of that phase. We discuss these res ults with reference to patterns of refuge use behavior during the mate guarding phase.