Meeting Abstract
The Viviparity-Driven Conflict Hypothesis (VDCH) predicts that the placenta provides a novel arena for conflict over resources. Parent-offspring conflict is a predicted to occur because the optimal quantity of resources for an offspring to get from its mother is more than is in the best interest of the mother to provide. This conflict is exaggerated if females’ mate with multiple males. 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. Alternatively, the offspring of males from foreign populations may be better (or worse) at acquiring resources from their mother. Heterandria formosa, a placental fish, 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 to determine whether mating with multiple males affects offspring number or size within and among broods. Our results suggest that the paternal population dictates offspring size in uni-directional crosses. However, when sperm is mixed from multiple populations of males, the size of the resulting offspring depends on how many males were used, and the resulting offspring size in these crosses is different depending on the female’s population of origin.
