Authors: Martin J. Gil, Fatima Guerrero And Valentin Perez-mellado

Abstract: We studied dieI variation in preferred body temperatures (T_P) of adult and subadult geckos (Tarentola mauritanica) in a laboratory thermogradient. Overall T_P averaged 31 .6°C and is significantly higher that the activity body temperatures recorded in the field. We did not detect differences in T_P between adult and subadult lizards. T_P varied according to a diel cycle. There was a gradual increase in T_P during the afternoon-early evening period, leading to peak values just before the beginning of the night-time activity period. During the subsequent hours, T_P s decrease again.

Authors: Adolfo Marco, Valentin Perez-mellado And Martin J. Gil-costa

Abstract: The mountain population of Lacerta schreiberi studied at the Sistema Central (Spain) showed a narrow and highly synchronized reproductive period, adjusted to short periods of annual activity, that are characteristic of these Iberian areas. Adult females reached sexual maturity at a minimum age of four years. Only one clutch of eggs is laid per year. The average clutch size of 14 eggs was positively correlated with female body size. Clutch weight was high (25 to 56% of net female weight), and incubation time was long (65 to 1 1 0 days). During incubation eggs reached three times their initial weight. We found a noticeable variability in some reproductive characteristics during the three years under study and among individual females. The greatest phenotypic plasticity was in the size of the eggs, incubation time, and the size of hatchlings, while clutch size showed a higher stability in its average values.

Authors: Jaime Bosch And Inmaculada López-bueis

Abstract: The dorsal pattern of six populations of Salamandra salamandra was studied. Several quantitative characters of the dorsal spots (number, area, perimeter, axes length, co-ordinates of the centre of gravity, etc.) were analysed using computer assisted technology. The study of these characters results in unexpected clustering of the populations. The population of Macizo de Pefialara, which is considered within S. s. bejarae seems to be closely related to the S. s. almanzoris populations.

Authors: J. R. Downie

Abstract: Eggs of the neotropical frog Leptodactylus fuscus (Anura: Leptodactylidae) are laid in foamy masses in burrows close to sites of temporary pools. After about two days, tadpoles hatch into the foam, but after two days further development, ifno rain has fallen, the tadpoles enter a period of developmental arrest, maintained until rain falls and the nest is inundated. Results reported here document the developmental status of the arrested tadpoles, and compare this with tadpoles that enter water immediately. Arrest involves a gradual slowing and eventual cessation of cell proliferation, a slowing of hatching gland degeneration, a cessation of limb bud morphogenesis and slowing of yolk utilization from intestinal lining cells. Arrest is not simply the result of lack of food, since the intestinal lining contains abundant yolk particles when it begins. The period of developmental arrest is not unlimited: around 20 days after egg deposition, the resultant tadpoles undergo progressive weight loss and eventually die; death occurred on average 27.5 days after egg deposition,under laboratory conditions.

Authors: J. R. Downie

Abstract: Several experiments were performed to test the hypothesis that foam made by hatched Leptodactylus fuscus tadpoles contains an inhibitor that maintains them in a state of developmental arrest. The results did not support the hypothesis. Tadpole-made foam did not inhibit the development of earlier stage L. fuscus, later stage L. fuscus or tadpoles of another species, Colostethus trinitatis, nor did removal from foam in itself release tadpoles from developmental arrest. Developmental arrest was found not to be obligate: tadpoles transferred to water at prearrest stages developed continuously through to later stages. Preliminary evidence suggested that transfer to water alone, irrespective of the presence of food, allowed tadpoles to bypass the arrest stage at least partially, possibly using their yolk reserves to continue development. The possibility that developmental arrest is mediated via Candida or Prototheca infection is briefly discussed.

Authors: John Davenport And Gayle A. Pearson