Female preference for preferred males is reversed under low oxygen conditions in the common goby (Pomatoschistus microps)

Abstract

Female preference for males that already have eggs in their nest has been reported in many fish species. The presence of eggs may provide a cue for copying the choice of previous females and may indicate that high-quality care will be available. Consistent with a review of 13 studies, we found that female common gobies (Pomatoschistus microps) preferred to spawn with males that had already been chosen by females and whose nests therefore already contained eggs. However, this preference was reversed under conditions of low dissolved oxygen. We would not expect this reversal if the second female were using eggs as a signal of male genetic attractiveness to other females unless the benefits were outweighed by direct selection. The reversal also could not be explained by differences in active courtship by males, as courtship rates did not differ under low oxygen between males with or without eggs. Low oxygen conditions corresponded with a nearly threefold increase in male ventilation of eggs and a reduction in time spent near a selecting female. The reversal is therefore most likely due to females avoiding males that would be unable to meet the demands of care of a second clutch under low oxygen conditions. Thus, an abiotic feature of the environment reveals plasticity of female choice, consistent with hypothesized changes in benefits of mating with preferred males.