Abstract

Two spermatogenetic cycles, vernal and aestival, have been described in temperate colubrid snakes. In both cycles, mating occurs in the spring, although vernal species produce spermatozoa in spring, just before mating, while aestival species use spermatozoa produced the previous summer. In this study, we describe the reproductive cycles of male and female Malpolon monspessulanus (Colubridae), and compare them to previously published cycles of five other snake species, four vernal and one aestival, inhabiting the same area. We also examine the consequences of both spermatogenesis cycles over the entire reproductive processes of male and female snakes in the south-eastern Iberian Peninsula. Vernal species mate later than do aestival species, as males must produce spermatozoa just prior to mating. However, vernal species are able to condense spermatogenesis and vitellogenesis processes, hence undertaking oviposition at the same time as aestival species. Here we discuss advantages of accomplishing the entire reproductive cycle in one (vernal species) or two (aestival species) calendar years. We also found that mature male M. monspessulanus exhibit decreased testes volume relative to body size. Large testes are expected in scenarios of sperm competition. The mating system of M. monspessulanus (territoriality, mate guarding, male–male combat) does not suggest sperm competition, hence it may be more advantageous for males of this species to invest in body size than in testes size.