A few years ago the population of male blue moon butterflies on the island of Samoa declined. One hypothesis for the decline of the male butterflies is that a parasite infected the cells of female butterflies. The parasite was passed to offspring through the females' eggs and killed the male butterfly embryos. At one point during the decline, nearly all the butterflies in the population was females, but after five years the number of males in the population increased significantly. Which explanation most likely accounts for the increase in the number of male butterflies in the five years after the initial parasite problem?​