The ancient genus Selaginella can reveal how natural selection shaped fundamental traits of plant reproduction like morphological differentiation of spores (a prerequisite for the evolution of seeds) and sexual division of reproductive investment. But almost nothing is known of the 'ecological theatre' in which Selaginella evolves. This project will examine the worldwide phylogenetic pattern of reproductive traits in the genus, and combine field and greenhouse studies of Australian and Malaysian species in order to test fundamental ideas in evolutionary ecology such as the theory of sex allocation, and begin to establish the ecological and adaptive counterpart to Selaginella's emerging role as a genomic model organism.