What do banana slugs know about reproduction?
Our familiar banana slug, Ariolimax californicus, denizen of moist forest floors, has solved one of the major paradoxes of life — sexual reproduction. As practiced by the great majority of animals, sex carries many costs, one being that only females produce offspring while the males simply consume resources and contribute nothing but sperm. And why would any female choose to dilute her genes with those from a male, when a clone could carry 100 percent of her genes? There must be some overriding advantage to sex, otherwise it would not be so prevalent. Most biologists argue that the advantage follows from the greater genetic diversity of siblings carrying various mixtures of genes derived from two parents. This diversity, they argue, gives some offspring a better chance of overcoming new challenges presented by evolving parasites, predators and environments. However, banana slugs have found a way to “have their cake and eat it” by having each sex partner produce both eggs and sperm. A
