MATERNAL EFFECTS ON OFFSPRING QUALITY IN POECILIID FISHES

We evaluated the effects of maternal environment on offspring size and composition in three species of poeciliid fishes. We chose food avail ability as the environmental factor for study. Mature females were ass igned to either high or low food for an interval of time, then randoml y reassigned to high or low food, with the restriction that there be e qual numbers in each of four treatments: high-high, high-low, low-high , and low-low food availability. The three species chosen for study di ffer in the pattern of maternal provisioning. Poecilia reticulata and Priapichthys festae mothers provide all resources necessary for develo pment as yolk, prior to fertilization. In contrast, Heterandria formos a mothers continue to provision the young throughout development. Thes e species also differ in whether or not they have superfetation, or th e ability to carry multiple broods of young in different stages of dev elopment. P. reticulata does not have superfetation while the other tw o species do. We were interested in whether the pattern of maternal pr ovisioning or superfetation influenced the maternal effect. The two le cithotrophic species responded to low food by producing larger young w ith greater fat reserves. H. formosa, the matrotrophic species, respon ded to low food by producing smaller young. We propose that the produc tion of large young in the face of low food availability might represe nt adaptive plasticity; matrotrophy might represent a constraint that prevents such an adaptive response. Superfetation had no impact on thi s maternal effect.