Egg presence, egg loss, and female mate preferences in the sand goby (Pomatoschistus minutus)

Abstract

We studied the effect of egg presence on female mate choice in a fish with paternal care. Females who were allowed a free choice between two males mated within a shorter time than females who were randomly assigned to a particular male. When a second female was allowed to choose among the males, she preferred the same male as the previous female. This result shows that females are concordant in their mate choice. When the initial female was randomly assigned to mate with one of two males (forced choice), the second female mated randomly with respect to the first one. Thus females do not prefer males with eggs. If the initial female was given a free choice, but the eggs were removed from the chosen male, the test female mated randomly. When both the males initially had mated but one randomly determined male's eggs were removed, the test female preferred the male who was still guarding eggs. These experiments show that females avoid spawning in unsuccessful nests. When the females in the free choice/egg removal experiment mated with the unsuccessful male there was a considerably bigger size difference in favor of this male than when the females mated with the other male. We conclude that female sand gobies show clear mate preferences, but that they do not prefer males with eggs over males without eggs. They do, however, avoid mating with males guarding unsuccessful nests. We therefore suggest that egg loss could be an important factor selecting for egg preference.