THE EVOLUTION OF SELF-FERTILIZATION IN PERENNIALS

Many plants are perennials, but studies of self-fertilization do not u sually include features of perennial life histories. We therefore deve lop models that include selfing, a simple form of perenniality, adult inbreeding depression, and an adult survivorship cost to seed producti on, Our analysis shows that inbreeding depression in adults diminishes the genetic transmission advantage associated with selfing, especiall y in long-lived perennials that experience inbreeding depression over many seasons. Perennials also pay a cost when selfing increases total seed set at the expense of future survivorship and reproduction. Such life-history considerations shed new light on the generalization that annuals self-fertilize more than perennials. Past research suggested r eproductive assurance as an explanation for this association, but comm on modes of selfing offer equal reproductive assurance to annuals and perennials. Instead, perennials may avoid selling because of adult inb reeding depression and the cost to future survivorship and reproductio n.