Intraspecific brood mixing and reduced polyandry in a maternal mouth-brooding cichlid

Microsatellite loci were used to evaluate the level of polyandry and intraspecific brood mixing in Protomelas c.f. spilopterus, a paedophagous, maternal mouth-brooding cichlid from Lake Malawi, Africa. We found that broods were fertilized by one to three males, which was a reduced level of multiple paternity compared to other mouth-brooding cichlids. Low density of breeding males and the risk of intraspecific predation are likely explanations for reduced polyandry. Intraspecific brood-mixing was found in four out of the six broods examined, with the proportions of foreign fry ranging from 6% to 65%. The potential origins of brood mixing are discussed, although no firm conclusions can be drawn given the limited behavioral observations for this species.