The Herpetological Journal

pp.111-117

Authors: Nora R. Ibargüengoytia 1 And Victor E. Cussac

Abstract: Female Liolaemus elongatus and Liolaemus pictus have biennial and triennial reproductive cycles respectively, with a low availability of reproductive females during the breeding season. Previous results have shown slight interspecific differences in sexual dimorphism between L. pictus and L. elongatus, coinciding with differential accessibility to females. Present results show major interspecific differences in the timing of spermatogenesis. Male L. pictus begin to reproduce during the first year of adulthood and remain active during a long breeding season. In contrast, male L. elongatus delay reproduction for one year and reproduce during a narrower period, in synchrony with the female reproductive cycle. Male L. elongatus showed an increasing testicular size during spermatogenesis, and a reduction in size when the first spermatozoa appear. Liolaemus pictus had spermatozoa in seminiferous tubules for the entire sampling period, from spring to autumn. The existence of severe thermal constraints for vitellogenesis and pregnancy set the following chain of causal events: environmental conditions - female cycle - male cycle and male dimorphic traits. This sequence of events shows how environmental cues can constrain the female cycle, and female availability, and thereby also affect the male cycle and the development of male dimorphic traits.

Keywords: Sexual dimorphism, Liolaemus, male reproductive cycles