Multiple Paternity in the Common Five-lined Skink (Plestiodon fasciatus)

Abstract

Multiple mating and sperm storage can influence reproductive strategies of males and females. Male reproductive success is often limited by the ability to acquire mates; therefore, males have evolved strategies to mate with multiple females. In contrast, the number of offspring a female produces is generally not limited by the quantity of sexual partners; thus, selection for multiple matings is expected to be weaker than in males. Evidence of polyandry and sperm storage is widespread among lizards. We investigated whether female Common Five- lined Skinks (Plestiodon fasciatus) could store viable sperm between reproductive cycles, estimated the frequency of multiple paternity, and examined the sharing of paternity within clutches. Females were unable to store viable sperm between successive clutches. Most clutches (65%) had multiple sires, but within those clutches, there was unequal sharing of paternity. Although we cannot determine the function of polyandry from our data, we suggest possible causes of polyandry in the mating system of this species. Multiple mating by males and females has been well documented in numerous vertebrate and invertebrate taxa (Birkhead and Moller, 1998). Although widespread, the evolution of polyandry is more difficult to explain based on the existing literature than is polygyny. For males, mating opportunities are the most severe limitation of reproductive success, and accordingly, selection has driven male strategies toward the acquisition of multiple females (Andersson, 1994; Birkhead and Moller, 1998; Birkhead, 2000). In contrast, for females, a single mating typically can fertilize their ova and reproductive success is generally not constrained by the number of partners (Bateman, 1948; Trivers, 1972; but see Madsen et al., 1992).