Authors: Cristina Arzabe, Cynara Xavier De Carvalho And Marcos A. Goes Costa

Authors: Félix B. Cruz

Authors: Nora R. Ibargüengoytía And Victor E. Cussac

Abstract: Squamate viviparity has evolved on several occasions, and probably independently within the genus Liolaemus itself. Hypotheses about the origin of reptilian viviparity emphasize the advantage of providing an adequate thermal environment for the embryo. At the same time, high latitudes and altitudes limit the availability of heat to perform vitellogenesis and gestation. The genus Liolaemus includes both oviparous and viviparous modes of reproduction, as well as reproductive cycles with great variations in the timing of the events. In the present work maximum juvenile size, sexual dimorphism, gonadal cycle and litter size of viviparous Liolaemus elongatus were studied. Female lizards may have annual or biennial cycles, but males reproduce annually in synchronization with the female cycle. Phenotypic plasticity may be one way that allows the species to cope with environmental constraints, and may be a reproductive adaptation that Liolaemus has evolved in response to the the cold climate in the highlands of southern South America.

Authors: Carmen Díaz- Paniagua

Abstract: A breeding population of small marbled newts in a temporary pond in SW Spain was sampled over five successive years. Males and females entered the pond just after it flooded in autumn. The adult aquatic season persisted until March or April, with maximum capture rates occurring mostly in January. Several sampling methods were used of which the most efficient was funnel trapping. Recapture rates were low. The population was estimated at about 1000 newts in 1987. Sex ratio did not differ from 1:1 in three seasons. In the other two seasons, which were characterized by low autumn rainfall, males outnumbered females by 2:1, probably as a result of many females failing to enter the pond to breed in those years. In the last two study years, the mean body size of newts was smaller than in previous years, possibly as a consequence of the adverse conditions of the two preceding autumns, which would have had repercussions for the growth of juveniles. An increase in physical condition and individual body mass throughout the aquatic season was observed in both sexes, confirming that the adult aquatic phase is advantageous for growth and maintenance of newts, as well as being necessary for reproduction. The age structure of the population was obtained in one of the seasons. Most males and females were 2-3 years old and a small percentage was one year old. The frequency of 1 year old mature females was lower than that of males. Females showed higher survival rates than males.

Authors: Adrian Hailey And John P. Loveridge

Abstract: It is difficult to devise physical models which precisely mimic the body temperatures (T_b 's) of large reptiles in the field. Studies of large reptiles have the compensating advantage that individuals can be fol lowed for long periods, so that translocated individuals can be used as ' living models'. We compare T_b's of two tortoise species in an enclosure in Harare (altitude 1500 m) with those in the field at Sengwa (900m), where mean air temperatures were about 5°C higher. Kinixys spekii, which occurs naturally near Harare, had similar T_b 's at the two sites (means 27.6 and 27.0°C, respectively). Geochelone pardalis had significantly lower T_b 's in Harare (29. 1 °C) than at Sengwa (32.6°C), even though activity was shifted towards midday in Harare. The inability to reach high T_b during activity may explain the absence of G. pardalis near Harare, and the distribution of this species in southern Africa.

Authors: M. A. Rodríguez-domínguez , C. Castillo , J. J. Coello And M. Molina-borja

Abstract: Morphological variation was investigated in 56 live adult specimens (3 1 male, 25 female) and ten dead near-hatching embryos of G. simonyi machadoi from the "Centro de Reproducción e Investigación del lagarto gigante del Hierro" (Frontera, El Hierro). Dimensions, scalation and teeth traits were measured and quantified. Males and females differed significantly (multivariate analysis of variance) in most of these traits, with values for males being greater than those for females. All traits significantly increased with SVL at a greater rate in males than in females, except for body weight, where no significant difference was found. A qualitative comparison between data from G. s. machadoi and those for ten G. s. simonyi showed that for most biometric traits, ranges overlapped for the two subspecies, but mean and maximum values were higher in G. s. simonyi. Hind limb length increased at a greater rate relative to SVL in G. s. simonyi than in G. s. machadoi.

Authors: Carl H. Ernst , James C . Wilgenbusch , Timothy P. Boucher And Steven W. Sekscienski

Abstract: Male Florida box turtles, Terrapene carolina bauri, grow proportionally longer relative to their height and width, than do females, resulting in a longer, flatter carapace, whereas females develop shorter, higher, and slightly narrower carapaces, possibly as an adaptation to accommodate hard-shelled eggs before oviposition. The subspecies has a typical growth pattern for a North American emydine turtle. Growth is rapid in juveniles, but starts to slow once maturity is reached at an age of 12-13 years. Growth rates approach an asymptote at about age 17 years in males and 16 years in females; very little growth occurs after age 20 years. Florida T. c. bauri grows at a slower annual rate than does T. c. carolina from Maryland despite having a longer annual activity and growth period. The data presented here may be considered to represent the average growth pattern for T. c. bauri in Florida. The cervical scute and all vertebral scutes have a greater width:length ratio in juveniles, but this ratio declines as the scutes lengthen with elongation of the carapace; however, the rate of increase in length varies among the scutes

Authors: Daniel G. Blackburn

Abstract: Among squamate reptiles, gravid females are frequently said to be able to resorb infertile and malformed eggs from their oviducts. This pattern, if it existed, would allow females to recycle nutrients from abortive attempts at reproduction, and to increase lifetime reproductive potential by modul . ating reproductive effort according to environmental circumstances. However, a review of the literature reveals that evidence for oviductal egg resorption is weak, and does not preclude other fates for abortive eggs (egg retention or expulsion). Furthermore, for the oviduct to resorb eggs would require that it have the functional properties of the digestive tract, properties that may be incompatible with its several reproductive functions. Future work should not assume oviductal egg resorption in squamates without definitive evidence that the eggs are not simply aborted or retained by females foll owing absorption of water.