Females of many squamates maintain viable sperm in their reproductive tract after insemination. This ‘female sperm storage’ (FSS), has several advantages and clear implications for squamate evolution by dramatically influencing life histories, mating systems, and sexual selection and conflict. In this chapter, we summarize the literature on the anatomy of FSS and reconstruct the evolution of sperm-storage location in squamate reptiles. Our major aim is to provide insights into the evolution of FSS in squamates, with a particular focus on the origin and early evolution of snakes. Various lizard lineages store sperm exclusively in crypts or tubules in the posterior oviduct. Most ‘basal’ lizards (gekkotans) and all ‘basal’ snakes (scolecophidians) studied thus far store sperm in tubules in the anterior oviduct. A few gekkotans and most alethniophidian snakes studied store (or potentially store) sperm in both oviductal regions. Some snakes apparently have evolved morphological adaptations to hold sperm in the posterior oviduct. Based on ancestral state reconstructions, we elaborate a scenario for the evolution of FSS in snakes.
