Meeting Abstract
The Viviparity-Driven Conflict Hypothesis (VDCH) predicts that the mammalian placenta provides a novel arena for parent-offspring conflict over resources. Parent-offspring conflict is a predicted to result from inequalities in the optimal quantity of resources transferred from the parent to the offspring. This conflict is exaggerated if females’ mate with multiple males because of lower coefficients of relatedness that result from being a half- rather than a full-sibling. Conflict theory predicts that there will be a reconciliation of conflict within populations but differences among populations in how conflict is resolved. If so, females may be able to recognize and differentially allocate resources to offspring sired by males from her own population. The principles of the VDCH can be extended to matrotrophic (embryonic mother-feeding) livebearing fishes (family: Poeciliidae) such as Heterandria formosa, which is particularly suited to test the predictions of the VDCH because their populations exhibit dramatic differences in offspring size. In this experiment, females from either large-offspring producing or small-offspring producing populations were artificially inseminated with a combination of sperm from males originating from their own population, a different population, or both. Additionally, treatments consisted of either two or four males (with the volume of sperm held constant) to determine whether mating with multiple males affects offspring number or size within and among broods. Preliminary results suggest that the paternal genome dictates offspring size when males from a single population are used. However, when sperm is mixed from multiple populations of males, the size of the resulting offspring is biased in one population.
