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

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