Sexual activity and plasma levels of sex steroids in the aspic viper Vipera aspis L. (Reptilia, Viperidae).

Reproductive behavior and associated sexual activity was studied in individual male and female Vipera aspis over a 3-year period in western France in an attempt to correlate mating behavior with blood levels of gonadal sex steroids. Males had higher average levels of both testosterone (T) and 5 alpha-dihydrotestosterone (DHT) than females. Levels of progesterone (P) did not differ significantly between the two sexes but estradiol-17 beta (E2) concentrations were significantly higher in females during the season of mating.

Histology of the reproductive tract of hybrids between gonochoristic males and parthenogenetic females of Lepidodactylus lugubris in French Polynesia (Reptilia, Gekkonidae).

Parthenogenetic populations of the gecko Lepidodactylus lugubris are widespread throughout Polynesia. They often occur parapatrically, and occasionally syntopically, with the increasingly rare bisexual populations. In these instances, a small number of hybrid individuals occur and include both "female" and "male" external phenotypes, both with greatly reduced gonads.

Patterns of breeding in two species of agamid lizards in the arid subtropical Pilbara region of Western Australia.

The reproductive cycles of two annual species of desert agamids have been studied over a 7-year period in the arid Pilbara region of Western Australia in an effort to identify proximate factors influencing their disparate modes of reproduction. Amphibolurus (= Ctenophorus) nuchalis breeds regularly in spring (September-October in the southern hemisphere) in the southern parts of its range, following reliable winter rainfall which stimulates insect abundance sufficient to sustain their reproductive effort. In the Pilbara region, however, winter rainfall is small and erratic and total rainfall is influenced primarily by summer cyclones.

Seasonal changes in plasma sex steroid levels in the male tuatara, Sphenodon punctatus, from Stephens Island, New Zealand.

A unique opportunity, occasioned by the sacrifice of five male tuataras (Sphenodon punctatus), was taken to measure the circulating levels of a number of sex steroids, and other parameters, at different seasons throughout the year on Stephens Island, New Zealand. Male tuataras exhibit continuous spermatocytogenesis throughout the year (H. Saint Girons and D.

[Effect of temperature on oxygen consumption of Vipera seoanei Lataste, 1879 (Reptilia, Viperidae) acclimatized to natural conditions].

Relations between respiration rates and temperature for 5 young Vipers previously maintained under natural climatic conditions were analysed from 15 to 30 degrees C. Oxygen consumption increases with temperature and concurrently with a constant Q10, at least for medium consumption, and drops as spontaneous activity is higher.