Showing papers in "Amphibia-reptilia in 1999"

Early metamorphosis in common frog Rana temporaria tadpoles at risk of drying: an experimental demonstration

Abstract: Does the development rate of common frog tadpoles accelerate if their habitat dries? To study this, the water level in experimental tanks was reduced shortly before time of metamorphosis. Water level remained high in control tanks. The experiment was performed at two different tadpole densities and replicated four times, with tadpoles from different source ponds. The experimental treatment, simulating a drying pond, resulted in earlier metamorphosis while no significant difference in size at metamorphosis was found. Resources per capita decreased as a result of the decreased water level so the increase in development rate was not an effect of feeding conditions. Temperatures in the tanks were such that it is unlikely that the increased development rate was due to temperature effects. I interpret the advancement of metamorphosis as an adaptive response to the threat of drying. This response has been documented for several other anuran species. All those breed in temporary water bodies, supporting the hypothesis that the trait is an evolved adaptation for breeding in such waters.

Salt tolerance of Rana temporaria: spawning site selection and survival during embryonic development (Amphibia, Anura)

Abstract: Spawning site selection of Rana temporaria is dependent on the salinity of the water. In the nature reserve 'Salzwiesen von Munzenberg' (Germany) the frogs avoided increased conductivity values, Cl - ion concentrations and salinities and selected lower values for spawning. In the laboratory Gosner stages 20/21 to 22/23 were more sensitive to sodium than the earlier G stages 8 to 20/21 (exposition for 72 h) though they were exposed for the shorter time period of 24 h. The 'no observed effect concentration' (NOEC) between G stages 8/9 and 20/21 was 648 ppm (3350 μS, 2.2‰ salinity) for Na + and 1872 ppm (6500 μS, 4.0‰ salinity) for K + . The NOEC between G stages 20/21 and 22/23 was 1490 ppm (7400 μS, 4.5‰ salinity) for Na + and for K + also 1872 ppm (6500 μS, 4.0‰ salinity). All developmental stages tolerated much higher ion concentrations and conductivity values in the laboratory than the adult frogs selected for spawning.

Foraging modes in lacertid lizards from southern Africa

Abstract: Most lacertids are active foragers, but intrafamilial variation in foraging mode is greater than in most lizard families. We collected data on eight species of African lacertids to assess this variation. Both active and ambush foraging occurred within Pedioplanis and Meroles. Meroles ctenodactylus had a proportion of time moving and proportion of attacked prey detected while moving intermediate to those for actively foraging and ambushing Pedioplanis, but its number of movements per minute was exceptionally high. This species has a unique mixed foraging mode. Like active foragers, it seeks food by tongue-flicking while moving and spends a high percentage of the time moving. Like ambush foragers, it searches visually for prey during pauses between movements. Our findings confirm published data on four Kalahari lacertids. We discuss the history of foraging modes in advanced lacertids.

Overgrowing forest as a possible cause for the local extinction of Vipera aspis in the northern Swiss Jura mountains

Abstract: In the northern Swiss Jura mountains, the Asp viper Vipera aspis was common until the 1940ies. During the past 50 years many local populations went extinct and nowadays the species is considered as threatened. We compared habitat characteristics of localities with extant viper populations with those of localities where the species became extinct. These two groups of localities did not differ in exposure, altitude, inclination, soil structure and cover of ground vegetation. However, localities where the species is still found were situated more frequently at forest edges, in dry meadows and at roadsides, whereas localities in which V. aspis became extinct were situated more frequently in forests. Tree density was lower at localities where the viper is still present. The results suggest that former habitats of V. aspis became overgrown by bushes and trees, which in turn may have led to a colder, more humid and thus unfavourable microclimate for V. aspis. We conclude that logging is an essential tool to maintain suitable habitat for this thermophilous ovoviviparous reptile.

Biparental care in the tadpole-feeding Amazonian treefrog Osteocephalus oophagus

Abstract: The Central Amazonian treefrog Osteocephalus oophagus breeds in water-filled bromeliad or palm tree leaf axils or in treeholes. The larvae feed on eggs provided by their parents; larvae not provided with eggs die. Survival of the larvae is ensured by the fact that the pair always spawns at the same site. They return at intervals of 5 to 7 days. Pair bonding is the rule in areas with low frog densities. The first eggs develop into tadpoles and later clutches of fertilized eggs serve as food. There is no apparent communication system between larvae and mother. After metamorphosis of the larvae the pair continues to lay eggs into the same leaf axils and these eggs also develop into tadpoles. This behavior is compared to that of other frogs that feed their tadpoles on eggs. It seems to be the least advanced mode of parental care involving tadpole feeding and demonstrates one of the initial steps that has led to more complex parental care behaviors in frogs.

Keratohyalin-like granules in embryonic and regenerating epidermis of lizards and Sphenodon punctatus (Reptilia, Lepidosauria)

Abstract: Epidermal shedding in lepidosaurians is determined by the formation of an intraepidermal shedding complex, made of an upper clear layer which interdigitates with a lower oberhautchen layer. The latter produces species-specific microornamentations. The ultrastructure of embryonic and regenerating epidermis in seven species of lizards representing five different squamate families (Gekkonidae, Agamidae, Lacertidae, Iguanidae and Scincidae), and on the regenerating caudal epidermis of the tuatara (Sphenodon punctatus, suborder Sphenodontia), has shown a broad variation in dimension and morphology of keratohyalin-like granules present in the clear layer of the shedding complex. Where the oberhautchen ornamentations are well developed, like in the setae of the climbing pads, keratohyalin-like granules appear more irregular, larger or more numerous. The present study suggests that keratohyalin-like granules might be involved in the formation of a fibrous network around the forming oberhautchen microornamentations.

Ecology and conservation of the Milos viper, Macrovipera schweizeri (Werner, 1935)

Abstract: The Milos viper (Macrovipera schweizeri) is nocturnal from early summer until mid-September. The typical habitat was maquis terrain with small and large bushes on gravel or rocky ground. Telemetric studies showed that cryptic basking behaviour was used during 23.5% of the localisations, and a preference for large bushes (77.7%). The mean distance moved between two succeeding days was 28.5 m (with s_ x , of 47.9), and in general, the male home range covered an area of 10 to 20 ha, while the female home range was smaller. Hibernacula were south facing and situated in the middle of the home ranges. Population density was 50 adult vipers per km 2 in the optimal habitats. The total population for western Milos was estimated to be around 2,500 adult vipers during the study period (1993-98). The present total population on Milos seems to be below 3,000 adult animals. The species has been isolated since the Pliocene, and adapted to a diet of passerine birds. A pattern of twice-a-year foraging during spring and autumn bird migrations was highlighted. During spring, the vipers tend to be concentrated around water pools; in the dry autumn nights they climb up trees for resting birds. In years with a cold spring or autumn, critical situations may occur with starvation, resulting in cyclic population patterns. Mid-May is the mating period. The female reproductive cycle is biennial. The sex ratio is nearly equal. Around 600 specimens reach adulthood and participate in the reproductive activities each year. Mining and fires destroy habitat. The yearly estimated removal by man and road killing of vipers is up to 500-600 adult specimens. Thus, the input and out-take of adult specimens is of the same magnitude, and equal to a yearly 25% turnover. This indicates a very delicate balance, and even a small change that increases the removed number can lead towards a rapid extinction. A conservation program is urgently needed and should include the establishment of protected areas, the closing of roads for night-time driving, and prohibition of increased mining activities.

Male-female spacing patterns in the lizard, Sceloporus virgatus

Abstract: The spatial distribution of Sceloporus virgatus in the Chiricahua Mountains of Arizona was studied during the breeding season. Male home ranges were, on average, more than four times larger than those of females. Home range overlap of both sexes was extensive, with most individuals overlapping multiple males and multiple females. Home range overlap of males with females was significantly correlated with an independently calculated estimate of male mating success. For most females (71%), one of the males overlapped a substantially larger portion of her home range than any other male. Similarly, for most females (76%) a single one of the overlapping males courted the female more often or was sighted at closer distances to the female. The remaining females did not associate primarily with a single male.

Movement- and attack-based indices of foraging mode and ambush foraging in some gekkonid and agamine lizards from Southern Africa.

Abstract: Two lizard foraging modes, ambush and active foraging, are usually quantified by the variables MPM (movements per minute) and PTM (proportion of time spent moving), but both variables may be affected by behaviors other than foraging. We introduce PAM, the proportion of attacks on prey discovered while lizards are moving (in relation to total attacks). PAM focuses exclusively on foraging behavior. Preliminary data reveal a very high, significant rank correlation between PAM and PTM, and a fairly high, but nonsignificant correlation between PAM and MPM. Collection of PAM data can be very time-consuming. In the absence of PAM, PTM appears to be a superior index of foraging activity to MPM, but all three indices provide valuable information on different aspects of foraging. We additionally present data for four agamine and five gekkonid species from southern Africa. The first quantitative data for agamines (all for Agama) agree with previous qualitative assessments that members of several agamine genera are ambush foragers. All the gekkonids, including three species of Rhotropus and one each of Pachydactylus and Phyllodactylus, are ambush foragers, like most geckos studied to date.

Development of testes and differentiation of germ cells in water frogs of the Rana esculenta - complex (Amphibia, Anura)

Abstract: The European water frog, Rana esculenta, is a hybrid whose genome is composed of haploid chromosome sets of its parental species R. lessonae and R. ridibunda. Prior to meiosis one of the parental sets is discarded and the other is duplicated (hybridogenesis). In the parental species sex differentiation begins at tadpole stages 28-30 (Gosner, 1960), at stages 30-36 the testes are composed of proliferating pale spermatogonia 1°. At stages 36-39 a new class of spermatogonia I° (dark) appears. Before first hibernation, seminiferous lobules are filled with cysts containing germ cells at various stages of spermatogenesis up to elongating spermatids. In R. esculenta gonad development is affected from the earliest stages: the gonads are smaller and composed of reduced number of spermatogonia I°. The phase of pale spermatogonia I° proliferation is prolonged up to the second year of life. The structure of the gonads, as well as that of germ cells themselves, are often abnormal.

Land salamanders of the family Hynobiidae from the Neogene and Quaternary of Europe

Abstract: A new extinct genus with two new species of land salamanders of the family Hynobiidae, from the Late Miocene of Polgardi (MN13), Hungary (Parahynobius kordosi gen. n. sp. n.) and from the Lower Pleistocene of Betfia IX/C (MQ1), Romania (Parahynobius betfianus gen. n. sp. n.), is described. The Late Miocene locality of Tardosbanya (MN12) and the Lower Pliocene locality of Osztramos 1C (MN 14), Hungary, also yielded several vertebrae, assigned with some doubt to the above genus (cf. Parahynobius). The new taxa belonged to the westernmost distributed stock of land salamanders of the Hynohius-group, which, based on the available fossil record, reached the Carpathian Basin during Late Miocene and disappeared from the area during Lower Pleistocene times. The Hynobiidae had a wider geographic distribution during the Tertiary and Quaternary compared to their present range, which is limited to Asia.

Phénologie de la reproduction chez Pelodytes punctatus Daudin, 1802 (Amphibia, Anura)

Abstract: Pelodytes punctatus est une espece dont les biotopes de reproduction sont localises en plaine principalement (90% des cas). De nouvelles donnees sur la phenologie de la reproduction ainsi que sur le type de milieu ont ete collectees durant 6 ans sur 4 regions comprenant plus de 35 sites. La periode de ponte principale survient au printemps mais on peut en observer une deuxieme en automne dans le sud de la France. Les œufs sont fixes en cordons par les femelles sur les tiges de plantes aquatiques. Le succes de l'eclosion depend de l'oxygenation de l'eau. La croissance larvaire est relativement rapide en conditions controlees (19°C ± 1°C) et les tetards se metamorphosent 40 a 60 jours apres l'eclosion. Dans le sud, deux categories de tetards sont observees en automne, les plus petits hivernent et se metamorphosent durant le printemps suivant.

Cytotaxonomic considerations with the description of two new NOR locations for South American toads, genus Bufo (Anura: Bufonidae)

Abstract: Cytogenetic studies were made on Brazilian Bufo: B. marinus, B. paracnemis, B. ictericus, B. rufus, B. arenarum, B. crucifer, Bufo granulosus, B. pygmaeus and B. margaritifer (= B. typhonius). All these species had a typical karyotype of 2n = 22. Species from the marinus and crucifer groups had NORs on Chromosome 7, species from the granulosus group had NORs on Chromosome 5, and B. margaritifer had NORs on Chromosome 10. The last two locations of NORs are described for the first time for the genus Bufo in South America.

A new Bolivian species of the genus Telmatobius (Anura: Leptodactylidae) with a humeral spine

Abstract: A new species of the genus Telmatobius is described based on two adult males from Chuspipata, Provincia Nor-Yungas, Departamento La Paz, Boliva, at 3050 m asl. This is the second species of the genus known to have an evident, externally projected humeral spine.

Notes on the natural history and habitat use of Eleutherodactylus fitzingeri (Anura: Leptodactylidae)

Abstract: Eleutherodactylus fitzingeri were studied during the dry and rainy seasons at an Atlantic lowland rainforest in Costa Rica. The frogs had one of three dorsal colour patterns (mottled, striped, uniform) and one of two ventral colour patterns (white, yellow). Males had significantly more often a yellow venter than females. Juveniles with a white belly were significantly smaller than juveniles with a yellow belly. Males perched higher than females and juveniles. Perch height in males did not vary with the time of day, weather conditions or behaviour. Calling males used more sheltered perches than silent males, and males calling by day used more sheltered perches than males calling by night. Reproductive activity increased greatly at the onset of the rainy season. Males showed little site attachment.

Mitochondrial DNA sequence data support the allocation of Greek mainland chameleons to Chamaeleo africanus

Abstract: Arnold, E.N., Burton, J.A. (1978): Reptiles and Amphibians of Britain and Europe. London, Collins & Sons.Bruno, S., Maugeri, S. (1990): Guida ai serpenti d’ Italia e d’ Europa. Milano, Editoriale Giorgio Mondadori.Carpenter, C.C., Ferguson, G.W. (1977): Variation and evolution of stereotyped behaviour in reptiles. In: Biologyof theReptilia, Vol. 7, p. 335-554. Gans, C., Tinkle, D.W.,Eds, London, New York, San Francisco, AcademicPress.Tomaselli, R., Balduzzi, A., Filipello, S. (1973): Carta Bioclimatica d’ Italia. Collana Verde 33, MinisteroAgricoltura eForeste, Roma.

Natural body temperature and kinetics of heat-shock protein synthesis in the toad-headed agamid lizard Phrynocephalus interscapularis

Abstract: We demonstrated that in the desert lizard Phrynocephalus interscapularis constitutive synthesis of both members of the hsp70 family of heat shock proteins takes place in summer. Elevation of environmental and body temperatures during the day was accompanied by a pronounced (2.0-2.5 times) increase in hsp70 synthesis. Synthesis of hsps continues during the day and drops to a basal level at night. Northern hybridization analysis demonstrated a higher content of hsp-coding RNA in the cells of P. interscapularis under normal physiological conditions in comparison with the lizard Lacerta vivipara, which inhabits regions with moderate climates.

Interactions between branchiate mole salamanders (Ambystoma talpoideum) and lesser sirens (Siren intermedia): asymmetrical competition and intraguild predation

Abstract: Using field sampling and experiments in natural and artificial ponds, I studied interactions between branchiate adult mole salamanders (Ambystoma talpoideum) and lesser sirens (Siren intermedia), two top predators in temporary ponds of the southeastern United States. The abundance and distribution of these two salamanders were independent among ponds, with A. talpoideum more numerous and widespread than S. intermedia. Both species were more likely to be found in ponds near other intermittent wetlands. Within a pond, captures of these two species were negatively correlated, and a field experiment showed that paedomorphic A. talpoideum avoided traps containing S. intermedia. An experiment in artificial ponds confirmed that interactions between these two species were highly asymmetrical; S. intermedia reduced the growth and recruitment of A. talpoideum without experiencing reciprocal. positive or negative effects. These results suggest that S. intermedia competes with and is an intraguild predator of A. talpoideum, limiting its growth and controlling its recruitment.

Summer habitat population estimate and body size variation in a high altitude population of Rana temporaria

Abstract: Population size and structure of the common frog, Rana temporaria, have been intensively studied by many authors during the last three decades (e.g. Cooke, 1975; Grossenbacher, 1980;Pascual and Montori, 1981;Hintermann,1984;Loman, 1984;Ryser, 1986;Elmberg, 1990; Kneitz, 1998). Most of these papers deal with lowor mid-altitude populations in Central Europe, which are generally located in at least partly forested habitats,whereas few studies have been carried out on the ecology of Rana temporaria in alpine environments (e.g., Balcells, 1975; Elmberg and Lundberg, 1991; Ryser, 1996). In the Alps and Pyrenees the species reaches altitudes as high as 2630 m (Alps: Grossenbacher, 1997) and at least 2700 m (Pyrenees, Ibones de la Facha near Circo de PiedraŽ ta: pers. obs.; Esteban, 1997). Records of almost 3000 m (Balcells, 1975) or 2950 m (Esteban, 1997) probably refer to Beck (1943) who reported R. temporaria at 2965 m (Pic de Cambalès). However, ponds and marshes around this mountain are only found at lower altitudes, and the occurrence of a R. temporaria population at a mountain summit is not probable; the 2965 m altitude information is thus rather doubtful (Grossenbacher, pers. comm.). From 6 to 29 July 1998 we studied R. temporaria specimens inhabiting the Ibón de las Ranas, a medium-sized glacial pond (water surface ca. 170 ́ 60 m; maximum depth 5 m), which is located at ca. 2200 m altitude in the Circo de PiedraŽ ta, western Pyrenees, Aragón, Spain (42° 49 ¢ N, 0° 17 ¢ W). The pond is in an area without forest cover; the only

Allometry and sexual dimorphism in the lung morphology of prairie rattlesnakes, Crotalus viridis viridis

Abstract: We quantified sexual dimorphism and allometric changes in the lung morphology of 160 juvenile and adult specimens of prairie rattlesnake, Crotalus viridis viridis, from a single population. In virtually all lung components, those of males are located more posteriorly than are those of females of the same body size. Males display a longer vascular component than females but there is no sexual dimorphism in size of the avascular component. Thus, males generally have longer lungs than do females at all body sizes. With increasing body size, the lung components are found more anteriorly, relative length of the vascular lung decreases, and relative length of the avascular lung increases in both sexes. However, total lung length increases isometrically with body size. These sexual and allometric differences suggest that intraspecific variation should be taken into account when lung size characters are used in snake systematic studies.

Predation on tadpoles by hatchlings of the freshwater turtle

Abstract: Experiments with Pelomedusa subrufa, a widespread African freshwater turtle, showed that this species consumed large quantities of tadpoles. Tadpoles preyed upon, comprised between 0.05 and 21.55% of the turtle's biomass. This demonstrated that Pelomedusa subrufa was neither gape limited nor did it ignore very small prey. Tadpoles with an ovoid body shape (Hemisus marmoratus, Hyperolius nitidulus, Ptychadena maccarthyensis), which shared, under natural conditions, the pond bottom microhabitat with the turtles, were more threatened than the robust tall-finned Kassina tadpoles that lived in the middle of the water column. The translucent, slow swimming Phrynomantis microps tadpole occurred in larger ponds and preferred the upper water column in deeper parts of the pond. This species was especially at risk in ponds with reduced water levels. Turtles, in contrast to fish or dragonfly larvae, are capable of migrating to other ponds. They therefore might have a profound regional influence on tadpole communities in ephemeral savanna ponds.

Two new species of anoles of the Norops crassulus group from Honduras (Reptilia: Sauria: Polychrotidae)

Abstract: Two new species of anoles of the Norops crassulus group are described from Honduras. Both are distinguished from all other species of the genus Norops by unique characteristics of scale morphology and meristics, limb proportions, and male dewlap coloration.

Seasonal water loss of the lizard Lophognathus temporalis in the wet-dry tropics of northern Australia

Abstract: Evaporative water loss (EWL) occurs principally across the skin (cutaneous water loss, CWL) of terrestrial reptiles (Shoemaker and Nagy, 1977; Mautz, 1982), but EWL also occurs across respiratory passages (respiratory water loss) and the eyes (ocular water loss) (Mautz, 1982). Over 70% of EWL in agamid lizards is from CWL (Eynan and Dmi’el, 1993). The factors determining the rate of CWL are skin resistance (Davis et al., 1980) and vapour density difference between the epidermis and the surrounding atmosphere (Zucker, 1980). Vapour density difference increases with increasing environmental temperature and wind speed and decreasing humidity and size of the animal (Davis et al., 1980). Respiratory water loss increases with aridity of habitat in agamid lizards (Leclaire, 1978). Ocular water loss may be a signiŽ cant component of water loss where no signiŽ cant barrier, such as transparent, spectacled eye-lids, exists (Mautz, 1982). Reptiles inhabiting extremely desiccating environments, such as deserts, require exceptionally efŽ cient water preserving mechanisms. CWL is usually relatively low in reptiles of such environments (Shoemaker and Nagy, 1977). Some lizards may have physiological adaptations to control CWL as they become dehydrated (Kobayashi et al., 1983; Dmi’el et al., 1997). Without such adaptations, EWL in lizards in a seasonal tropical environment is determined by the animal’s activity (Heatwole and Vernon, 1977) and the environmental variables of temperature (Thorpe and Kontagiannis, 1977) and humidity (Hillman and Gorman, 1977). Although lizards of wet-dry tropical areas experience reasonably uniform temperatures throughout the year, they encounter a vast range of seasonal humidities and rainfall, and many species reduce activities during the driest times of the year as a response

Intraspecific variability in nucleolar organiser position in Lacerta (Timon) lepida

Abstract: Discusses several studies on herpetology. Intraspecific variability in nucleolar organiser position in Lacerta (Timon) lepida; Habitat characteristics of the spectacled salamander Salamandrina terdigitata in southern Latium in Central Italy; Body temperatures of the monitor lizard Varanus tristis during the breeding season.

Cranial morphology of Rafetus euphraticus (Daudin, 1801) from Southeastern Anatolia

Abstract: Observations on cranial morphology were made on Euphrates soft-shelled turtles, Rafetus euphraticus, sampled in the Euphrates and Tigris rivers and tributaries, Southeastern Anatolia. The vomer separates the maxillaries in half of the specimens, whereas the maxillae meet on the vomer in others. The parietal has no contribution in the formation of the foramen nervi trigemini due to the contact between the prootic and the epipterygoid. There are variations in the contacts of the basisphenoid and in the formation of the trigeminal region, a prootic-epipterygoid contact participates in the trigeminal region. The contacts of the vomer-pterygoid, the vomer-basisphenoid and the vomer-pterygoid-basisphenoid are observed in some specimens. In one specimen, the parietal contacts the opisthotic. All specimens have the symphyseal ridge, althought it is weak and barely discernible.