The Herpetological Journal

pp. 141-148
Authors: Garda, Adrian Antonio; Costa, Gabriel Correa; França, Frederico Gustavo Rodrigues & Mesquita, Daniel Oliveira

Abstract: Lysapsus currently comprises three species distributed east of the Andes, from Guyana to northern Argentina. Lysapsus limellum occurs along the Amazon and Paraná river basins in ponds associated with river floodplains. We analyse geographic distribution, diet, reproduction, habitat use and diel activity of L. limellum from several populations in the Brazilian Amazon. Wide floodplains and open areas are common features of habitats of L. limellum, and populations are found either in savanna fragments or in floodplains along the Amazon river and its major tributaries. In savanna fragments of Humaitá, Amazonas, L. limellum is active during day and night and prefers areas with floating vegetation only. Frogs are active and prone to move during the day but remain motionless and call more at night. Most important diet items were dipterans, hemipterans/homopterans and odonates, underscoring the generalist behaviour of the species and its particular preference for dipterans. Females were significantly larger than males, but females and males were not different in shape. Neither number nor volume of eggs was related to female snout–urostyle length (SUL), while testis volume was significantly related to male SUL. In summary, L. limellum is a widely distributed small aquatic frog with a generalist diet that inhabits ponds in open floodplains.

Keywords: DIEL ACTIVITY, DIET, GEOGRAPHIC DISTRIBUTION, ANURA, SEXUAL DIMORPHISM, HYLIDAE

pp. 149-160
Authors: Vásquez, Mauricio and Torres-Pérez, Fernando and Lamborot, Madeleine

Abstract: Allozyme variability was assessed within and between 18 samples of four chromosomal races of the Liolaemus monticola complex: Southern, 2n=34, Northern, 2n=38–40, Multiple Fission, 2n=42–44 and Northern modified 1, 2n=38–40. This is an endemic montane Chilean lizard characterized by extensive chromosomal polytypy. The population genetic structure was studied by means of allozyme electrophoresis of 20 presumptive loci. Population heterogeneity analysis carried out by the estimation of Weir and Cockerham's F-statistic (), demonstrated substantial genetic differentiation among populations. The u-statistic, genetic distance data and multivariate analyses show that genetic variation is distributed into geographically coherent population groups in accordance with three of the four chromosome races. The greatest differentiation occurs between all populations of the Southern, 2n=34 race and a second group that includes all populations from the Northern, 2n=38–40 plus Northern mod 1, 2n=38–40 races, separated from the Multiple Fissions, 2n=42–44 race. As riverine barriers also separate these chromosomal races, we do not attribute the observed differentiation to isolation-by-distance or the chromosome characterization for each race. Possible routes of migration and colonization are proposed.

Keywords: ALLOZYME VARIABILITY, CHROMOSOMAL RACES, CENTRAL CHILE, LIOLAEMIDAE, SQUAMATA

pp. 161-166
Authors: Romansic, John M.; Higashi, Elise M.; Diez, Kristin A. & Blaustein, Andrew R.

Abstract: Recent losses of worldwide biodiversity include population declines and extinctions in many amphibian populations. Many factors, including pathogens, are contributing to amphibian population declines. One pathogen, a water mould of the genus Saprolegnia, causes mortality in early life stages of amphibians and may contribute to the declines of specific amphibian populations. Most of our knowledge of how Saprolegnia affects amphibians comes from studies of embryos. The effects of Saprolegnia on post-metamorphic amphibians are poorly known. Therefore, in the laboratory, we investigated the susceptibility of newly-metamorphosed juvenile amphibians to Saprolegnia in four frog species: Bufo boreas (western toad), Pseudacris regilla (Pacific treefrog), Rana aurora (red-legged frog) and R. cascadae (Cascades frog). We found that juvenile R. cascadae exposed to Saprolegnia had greater rates of mortality than unexposed controls. In the other species, survival was also lower in the Saprolegnia treatments compared with controls but these differences were not statistically significant. Combined effects of Saprolegnia in both embryonic and juvenile stages may make the populations of R. cascadae especially vulnerable.

Keywords: METAMORPH, BUFO BOREAS, PSEUDACRIS REGILLA, LIFE HISTORY STAGE, AMPHIBIAN POPULATION DECLINES, RANA AURORA, R. CASCADAE

pp. 167-173
Authors: Miaud, Claude; Ūzüm, Nazan; Avci, Aziz & Olgun, Kurtulus

Abstract: We estimated the age, size and growth patterns of a mountain ranid, Rana holtzi, from Central Anatolia, using skeletochronology. We used lines of arrested growth (LAGs) recorded in phalanges to estimate the age of juveniles and adults. Results showed that age at maturity in this population was 4–5 years (median age of juveniles was 3.5 yrs and minimum age for adults was 4.0 yrs for both sexes). Median ages of males and females were similar (6 yrs) and longevity reached 8.0 yrs for males and 10.5 yrs for females. Mean body and tibia length of males was significantly larger than that of females. Growth of the Anatolian mountain frog was well described by the von Bertalanffy model, and males and females did not differ in growth parameters. These demographic parameters are compared with those obtained with other amphibians, especially ranids. The sexual size dimorphism observed – larger males than females – has rarely been observed previously and should prompt observers to collect other biological information on this rare endemic species.

Keywords: SKELETOCHRONOLOGY, SEXUAL SIZE DIMORPHISM, AMPHIBIAN, LIFE-HISTORY TRAIT

pp. 174-182
Authors: Vos, Claire C.; Goedhart, Paul W.; Lammertsma, Dennis R. & Spitzen-Van der Sluijs, Annemarieke M.

Abstract: The implications of habitat fragmentation go beyond changes in the size and composition of suitable habitat patches. In fragmented landscapes, #matrix##permeability# influences the dispersal of organisms, thereby affecting the persistence of populations in such landscapes. We investigated the effect of habitat composition on the movement of adult and recently metamorphosed juvenile common frogs (Rana temporaria) emigrating from a pond in an agricultural landscape. One question driving our research was: do the numbers of captured individuals differ between habitat types? Such a difference would indicate avoidance of or preference for certain habitats. A subsidiary question was: does the response to landscape composition differ between adults and juveniles? We found significant differences in the numbers of frogs trapped in various habitat types. Adult and juvenile common frogs preferred extensive meadows and hedgerows above other habitat types. Arable land was the most avoided habitat type, but short-cut pastures and road verges were also avoided. For instance, almost 10 times more juveniles and four times more adults were caught in meadows than in arable land. Hedgerows were also frequented often, with four times more juveniles and 2.2 times more adults captured compared to arable land. Juveniles displayed more clear-cut preference and avoidance of habitat types than adults. These findings suggest that intensively farmed landscapes form a larger barrier for juveniles than for adults, from which we conclude that different life stages of the same species may react differently to matrix composition. The demonstrated influence of matrix composition on frog dispersal underlines the importance of having well-connected habitat networks to ensure the sustainability of amphibian communities in agricultural landscapes.

Keywords: FIELD EXPERIMENT, CONNECTIVITY, NATURE CONSERVATION, BEHAVIOUR, AMPHIBIANS, HABITAT FRAGMENTATION, DISPERSAL

pp. 183-191
Authors: Vignoli, Leonardo; Bombi, Pierluigi; D'Amen, Manuela & Bologna, Marco A.

Abstract: The aim of this study was to analyse the diet composition and feeding strategy of a heterochronic population of the Alpine newt, Triturus alpestris apuanus (Bonaparte, 1839), in a high-altitude pond in the south-western Alps, characterized by a reduced aquatic habitat and low environmental heterogeneity. The co-existence of both adult newt morphs in such a non-complex habitat with short suitable hydroperiod (water surface free of ice) may not be governed by different microhabitat selection or temporal activity, but could be due to diet composition differentiation among morphs. The diet of the newt was examined and compared with prey availability in summer and autumn. Both numerical and volumetric analyses of the gut contents showed that: 1) metamorphs represented a homogeneous group clearly linked to epineustonic prey categories (exogenous arthropods), whereas paedomorphs showed a prey selection mainly towards planktonic food categories; 2) evident seasonal variations in diet composition not connected to aquatic prey availability were observed in the studied forms; 3) metamorphs and paedomorphs may possibly avoid competition (if there is any) through food resource partitioning rather than microhabitat selection.

Keywords: FEEDING STRATEGY, HIGH-ALTITUDE POND, SALAMANDRIDAE, ALPINE NEWT, AMPHIBIA

pp. 192-198
Authors: Wilkinson, John W.; Beebee, Trevor J.C. & Griffiths, Richard A

Abstract: On Jersey (British Channel Islands), common toads often reproduce in small, urban ponds. This atypical breeding strategy has implications for their persistence and they have declined on the island in recent times. We used polymorphic microsatellite markers to compare genetic diversity in Bufo bufo from five different ponds in Jersey with two populations from north-west France. Genetic diversity of Jersey toads was comparable with that of populations elsewhere in Europe. Numbers of breeding female toads in Jersey were correlated with pond area but estimators of genetic diversity were unrelated to pond area or female numbers. F_st estimates and isolation by distance tests indicated that there is little gene flow between breeding sites on the island. Jersey populations last shared a common ancestor with those of north-west France long before the island's physical separation about 6000 years ago. Toads have a long history in Jersey and were once probably very numerous there. The average effective historical population size of Jersey toads is estimated to be 15,000–16,000. Although genetic diversity of Jersey B. bufo is currently quite high, recent developments on the island may threaten this situation in the near future.

Keywords: SMALL POPULATIONS, GENETIC DIVERSITY, CONSERVATION, COMMON TOAD

pp. 199-203
Authors: Smith, Geoffrey R.; Burgett, Amber A.; Sparks, Kathryn A.; Temple, Kathleen G. & Winter, Kristen E.

Abstract: The presence of predators or predator cues has an effect on the behaviour of tadpoles of several species of anurans. We used a mesocosm experiment to examine whether bullfrog (Rana catesbeiana) tadpoles might 1) alter their activity levels in response to variations in density and the presence of bluegill sunfish (Lepomis macrochirus), and 2) alter their daily activity cycle in response to variations in density and the presence of bluegill. The bullfrog tadpoles in our experiments showed a clear temporal pattern of activity, with activity always peaking during the evening or nighttime hours. Tadpole density had no effect on activity levels. We observed depressed activity levels in the presence of bluegill in the first observation period (30 June–1 July). Bluegill tended to depress activity levels in the second observation period (7–8 July), but this was not statistically significant. We observed elevated activity levels in tadpoles in the presence of bluegill during the third observation period (14–15 July). Neither bluegill nor tadpole density had an effect on the temporal pattern of activity in the bullfrog tadpoles. In addition to showing that fish can mediate activity in bullfrog tadpoles, our results suggest that the responses of tadpoles to the presence of predators can vary over time, and thus using a single observation could influence the conclusions that may be drawn.

Keywords: DIEL ACTIVITY, PREDATOR-PREY RELATIONSHIPS, PREDATION

pp. 204-207
Authors: Moreno-Rueda, Gregorio & Pleguezuelos, Juan M.

Abstract: The relationship between temperature and rates of detection of the Mediterranean snake Malpolon monspessulanus (Montpellier snake) in the wild was analysed over a 26-year period. We used records of live and freshly road-killed snakes in south-eastern Spain. A short-term effect of temperature on rates of snake detection was found: the higher the yearly temperature, the higher the snake detectability was that year. Moreover, a long-term effect of temperature on snake detectability was found, as snake abundance in year x was also strongly affected by temperature during year x– 1 and x–2. A multiple-regression model demonstrated that these effects were independent. These long-term effects are probably due to an effect of temperature on snake population dynamics.

Keywords: ABUNDANCE, CLIMATE, MONTPELLIER SNAKE, SPAIN, POPULATION DYNAMICS