The Herpetological Journal

pp.425-434

Authors: Adrian Hailey And N . S . Loumbourdis

Abstract: Female Testudo hermanni at Alyki, northern Greece were sexually mature at a mean straight carapace length of 150mm, based on the frequency of finding eggs by X-ray or oxytocin injection during the nesting season. Oxytocin-induced egg laying behaviour is described. Egg width (r = 0.49), shape (r = -0.32) and weight (r = 0.30) were all significantly related to body size. Hatchling wet weight was strongly related to egg weight. Hatchlings of T. hermanni were lighter than those of T. graeca and T. marginata in terms of dry weight/egg weight. This pattern reflects the low energy content of T. hermanni eggs, and is possibly a consequence of the use of more productive habitats by this species. Clutch size and clutch mass were weakly related to body size; reproductive potential declined in the largest females. Simple and stratified calculations gave similar estimates of the total reproductive potential of adult females in two populations at Alyki. There were, in round numbers, 250 adult females on the main heath producing 1 ,700 eggs per year, and 65 adult females on the salt works heath producing 450 eggs per year. Nest predation was low at A lyki, judging from the rarity of destroyed natural nests. This was confirmed by burying chicken eggs to stimulate tortoise nests. About 90 per cent of nests probably remain undisturbed during the incubation period.

pp.435-446

Authors: Migufi. Lizana. Valentin Pérez-mellado And Maria José Ciudad

Abstract: This study examines the structure of an Amphibian community. composed of 10 species in the Central System of Spain. We studied resource partitioning in the main dimensions of the niche (food, space and time). the overlap in each dimension and the overall overlap. From a multidimensional scaling analysis (MDS) of the overlap matrices we inferred that the spatial dimension is the main factor responsible for species segregation. Overlap along the time and food dimensions was significantly correlated. The community is structured into three guilds formed, respectively by the aquatic anurans. the terrestrial anurans together with a terrestrial salamander, and the newts.

pp.447-453

Authors: Carmen Diaz-Paniagua

Abstract: Breeding habitats of 10 amphibian species were investigated and classified by their physical characteristics. The relative larval abundance of the species was analysed in 15 temporary ponds, resulting in positive correlations with the area of the ponds, whereas negative correlations were found between species diversity and the persistence of the ponds. Regarding the use of their habitats, one species was not correlated with any one, and among the others, two groups of species were differentiated because of their negative associations.

pp.454-457

Authors: Trevor J. C. Beebee

Abstract: (I) Protein electrophoretic patterns from early life stages of two anurans, Bufo bufo and Bufo calamita, were compared. Samples were taken from two widely-separated populations of each species.
(2) Spawn jelly of the two toads could be distinguished reliably by t he difference in molecular weight of a single major component (30,000 in B. bufo, 35,000 in B. calamita).
(3) Small tadpole total proteins could be distinguished by the presence (B. bufo) or virtual absence (B. calamita) of two characteristic proteins of M rs 49,000 and 53,000.
( 4) Large tadpole tailfin proteins also differed in a species-specific way; B. bufo exhibited a strong band of Mr 62,000 that was almost absent in B. calamita, while the latter species had a doublet (Mrs 57,000 and 58,000) instead of the single 57,000 Mr polypeptide seen in B. bufo.

pp.458-462

Authors: D. C. Deeming And M. W. J. Ferguson

Abstract: The mass, length and breadth of 572 eggs of Alligator mississippiensis were measured and described as a complete sample and as subsets of 14 clutches. Egg volume and density were calculated. A multiple regression equation was generated to predict initial egg mass from egg length and breadth. A weight coefficient (KM) was determined for alligator eggs and its value was compared both to published values for avian eggs and to values for other crocodilian eggs calculated from literature data. The value of KM in crocodilians was higher than in avian eggs implying that the density of alligator eggs was much higher than the density of avian eggs. Egg volume in alligators was also estimated using the volume coefficient (Ky) for avian eggs but this was found not to be applicable.

pp.462-465

Authors: C. J. Reading

Abstract: In a series of laboratory experiments, male palmate newts that had no previous experience of anuran tadpoles as potential prey were conditioned for five days to small worms, common frog tadpoles, common toad tadpoles or a 50:50 mixture of frog+toad tadpoles. During three experiments, conditioned newts were offered I) a 50:50 mixture of frog+toad tadpoles 2) only frog tadpoles or 3) only toad tadpoles.
The results showed that palmate newts with no previous experience of either frog or toad tadpoles very quickly learnt to distinguish between t hem and take only frog tadpoles. This was supported by the results of a fourth experiment using male palmate newts from a pond that contained both tadpole species. Common toad tadpoles were almost totally rejected.
The conclusion is, that common frog tadpoles gain no long term protection against predation from palmate newts through associating with common toad tadpoles.

pp.465-473

Authors: Antonia M. Cirer And Juan-pablo Martinez-rica

Abstract: The variation in morphological and colouring features shown by the insular lacertid populations of Podarcis pityusensis is discussed from the point of view of their adaptive advantages to specific insular ecosystems. Insularity factors, i.e. area and island-age, have been found to be related t.o average body size, and the average luminosity of each population. Populations tend to show a size increase, a greater morphological homogeneity and darker dorsal colouring on smaller and older islands. The advantages of larger size and melanism are discussed as well as their possible causes in the insular microecosystems of the Pityusic Archipelago. Genetic drift seems to play a secondary role, whereas a positive selection in favour of melanism and giant ism is observed. Both features are not linked as cause and effect, but seem to share a common cause: isolation and time enough to allow selection to take place. Predation, though slight in degree, does exist, and seems to be one of the selective pressures favouring melanism, together with the parallel trend towards an increase in body size and the need to an effective thermoregulation during the early hours of the day.

pp.474-477

Authors: Erstratios D. Vala Kos And Rosa-maria Polymeni

Abstract: This report gives data on the feeding ecology of Cyrtodactylus kotschyi (Sauria-Gekkonidae), during the wet season in the mediterranean ecosystems of the Aegean. C. korsch ri feeds mainly on the larvae of insects. There are no significant differences in the food of this gecko among the different populations in the Aegean ecosystems.