Variation in endocrine activity in relation to the reproductive cycles of viviparous lizards Phymaturus from Argentin

BORETTO, J. M.; JAHN, G.A.; FORNÉS, M.W.; IBARGUENGOYTIA

San Carlos de Bariloche

Congreso; VI Southen Connection Congress; 2010

The harsh habitats of Phymaturus lizards in the Andean Highlands and the Patagonian Steppe ofArgentina, together with the inability of viviparous to perform vitellogenesis during pregnancy, constrain reproductive cycles. Herein we report the first study of endocrine responses linked to differences in reproduction in P. antofagastensis, P. punae, P. cf. palluma, P. zapalensis, and P. tenebrosus. Hormone assays and ultrastructural studies were used to determine serum estrogen and progesterone in females, serum testosterone in males, and the steroidogenic activity of tubular and interstitial compartments of testes. Females showed interspecific differences in hormone cycles, and males showed interspecific differences to coordinate with female cycles. Testosterone peaks indicate that mating occurs in spring in P. zapalensis, and in mid to late summer in P. antofagastensis and P. punae, respectively. Males of P. cf. palluma with high testosterone were captured throughout the active season. Morphological features characteristic of steroidogenic activity during the spermatogenic cycle were observed in Leydig andSertoli cells, and evidence of temporal asynchrony in steroid synthesis between testicular compartments were found in all species, especially in P. antofagastensis. Temporal separation of steroidogenic activity appears to propitiate the synchronization of male and female cycles, and the adjustment of reproductive activity to the physiological and environmental constraints.