Females increase parental care, but not fecundity, when mated to high-quality males in a biparental fish

Abstract

Positive differential allocation predicts that females will increase their parental investment when mated to high-quality males due to the benefits that these males provide to offspring. Differential allocation predicts trade-offs between current and future reproduction, but investment trade-offs can also occur within a breeding event for species that provide parental care. However, differential allocation studies that have examined investment in both gametic effort and parental care remain rare and have only been conducted in birds. Fish may have more conservative investment strategies due to the large effect that current reproductive investment has on future reproductive potential. We examined gametic effort and parental care in the convict cichlid, Amatitlania siquia, a biparental fish, in response to male size, a proxy for quality. We randomly mated females to either large or small males and measured fecundity and parental behaviour of both parents. Females mated to large males did not increase their fecundity, but did provide more parental care to offspring during the larval stage, which is when male desertion in natural populations is most likely. Male size did not predict the amount of paternal care provided to offspring during the larval stage. Female condition at the end of the breeding event was negatively associated with higher fecundity and level of maternal care provided. The observed pattern of maternal investment suggests that females limit costs to future reproduction by limiting their increased investment to only one component of their reproductive effort. The increase in maternal investment during the larval stage may also serve to stabilize the pair bond and ensure continued male care, which ultimately increases the reproductive success of both parents. These results highlight important taxonomic and parental care pattern differences and broaden our understanding of the factors that influence differential allocation in diverse taxa.