Reproductive plasticity in the lizard Ameiva ameiva across distinct climatic domains in Brazil

The Neotropical lizard Ameiva ameiva is widespread in Brazil, occurring in contrasting climatic regimes that can shape its reproductive tactics. Here, we compared reproductive traits of three populations from equatorial, tropical wet-dry and tropical equatorial domains using museum specimens to evaluate geographic variation in reproductive tactics. We examined male and female reproductive tracts macro- and microscopically to characterize individual and population-level reproductive cycles. Males produced sperm year-round, and most individuals remained in recrudescence or spermiogenesis. Females showed follicular growth and oviductal changes that tracked vitellogenic stages and seasons, revealing population-specific adjustments. Mating coincided with vitellogenesis and ovulation in all populations, and the presence of mating plugs and stored sperm may indicate that females can produce multiple clutches per reproductive season. Together, these patterns show that A. ameiva exhibits a continuous reproductive cycle at the individual level but a seasonal, semi-synchronous cycle at the population level. Temporal differences among populations, particularly in the timing of vitellogenesis and mating, thus demonstrate reproductive plasticity that may contribute to the species's ability to persist across diverse and changing environments.