The Herpetological Journal

pp. 187-197

Authors: Doris Preininger, Stephan Handschuh, Markus Boeckle, Marc Sztatecsny & Walter Hödl

Abstract: In anurans, males have larger laryngeal structures than females and produce conspicuous species-specific calls in various social contexts. Knowledge of female vocalisations is not well established and we start by summarising available spectral and behavioural information on calls in females. We then present novel data on female and male calls in Staurois guttatus and ask how larynx morphology influences call characteristics. While there was no difference in the dominant frequency between the sexes, sound pressure of female calls was lower than in males suggesting that they could be masked by ambient stream noise in the natural habitat. In an experimental setup, unreceptive females started calling when approached by a male less than 30 cm away, indicating an agonistic function of calling behaviour. In accordance with the overall size dimorphism in S. guttatus, laryngeal muscles as analysed by microCT were larger in females than in males whereas a reverse dimorphism was reported for most anuran species with silent and vocal females. We argue that in noisy environments such as streams, small male larynx size associated with high frequency calls is advantageous due to reduced masking and discuss the functional differences and communalities in signalling behaviour between the sexes and in the genus Staurois.

Key words:  anuran, female calls, laryngeal structures, noisy environment, visual signal

pp. 199-205

Authors: P. Pafilis, S. Meiri, K. Sagonas, D. Karakasi, E. Kourelou & E.D. Valakos

Abstract: Effective digestion is decisive for survival. In nature, where most animals feed sporadically, high digestive performance guarantees they will gain the most out of their infrequent meals. Larger body size implies higher energy requirements and digestion should function properly to provide this extra energy. Comparing Skyros wall lizards (Podarcis gaigeae) from Skyros Island to large (“giant”) lizards from a nearby islet, we tested the hypothesis that digestion in large individuals is more efficient than in small individuals. We anticipated that giant lizards would have higher gut passage time (GPT), longer gastrointestinal (GI) tracts and higher apparent digestive efficiencies (ADE) for lipids, sugars and proteins. These predictions were only partially verified. Giant lizards indeed had longer (than expected based on body length) GI tract and longer GPTs but achieved higher ADE only for proteins, while ADEs for lipids and sugars did not differ from the normal-sized lizards. We postulated that the observed deviations from the typical digestive pattern are explained by cannibalism being more prominent on the islet. Giant lizards regularly consume tail fragments of their conspecifics and even entire juveniles. To break down their hard-to-digest vertebrate prey, they need to extend GPT and thus they have developed a longer GI tract. Also, to fuel tail regeneration they have to raise ADEproteins. It seems that larger size, through the evolution of longer GI tract, enables giant lizards to take advantage of tails lost in agonistic encounters as a valuable food source.

 Key words:  body size, cannibalism, digestion, gigantism, islands, reptiles

pp. 207-211

Authors: Shohei Komaki, Takeshi Igawa, Si-Min Lin & Masayuki Sumida

Abstract: Physiological tolerance to variable environmental conditions is essential for species to disperse over habitat boundaries and sustain populations in new habitats. In particular, salinity and temperature are one of the major factors determining species’ distributions. The tree frog Buergeria japonica is the most widely distributed amphibian species found in the Ryukyu Archipelago in Japan and Taiwan, and uses a wide range of breeding sites. Such characteristics suggest a high salinity and thermal tolerance in B. japonica tadpoles. We measured the salinity and thermal tolerance of tadpoles from three islands to determine if physiological tolerance could have contributed to the wide dispersal and survival across different environments. The critical salinity of B. japonica was 10–11‰, a value markedly below seawater. We also observed a critical maximum temperature of approximately 40°C, a value which is higher than what is commonly observed for other anuran species. This high thermal tolerance may have favoured island dispersal and survival, particularly in volcanic islands.

 Key words:  adaptation, geothermal hot springs, physiological tolerances, Ryukyu Archipelago, survival rate, Taiwan, volcanic islands

Online appendix for 04. Does tail regeneration following autotomy restore lizard sprint speed? Evidence from the lacertid Psammodromus algirus

pp. 213-218

Authors: Francisco Javier Zamora-Camacho, María Virtudes Rubiño-Hispán, Senda Reguera & Gregorio Moreno-Rueda

Abstract: Tail autotomy is a widespread antipredator strategy among lizards, which consists of the capability of willingly detaching a portion of the tail in order to escape predator attacks. Nonetheless, tail autotomy has a number of costs, including reduced sprint speed which increases predation risk. However, lizards regenerate the tail following autotomy, although a regenerated tail is usually shorter and histologically different from the original tail. In the present work, we assess the effect of tail regeneration on sprint speed by comparing Psammodromus algirus lizards with intact and regenerated tails under controlled laboratory conditions. We found that sprint speed was similar in lizards with intact and regenerated tails. Therefore, tail regeneration following autotomy effectively restored sprint speed, although regenerated tails were shorter than intact ones. Thus, regenerating shorter tails could diminish anabolic costs with no negative consequences on flight ability.

 Key words: intact tail, lizard, regenerated tail, sprint speed, tail autotomy

Online appendix for 05. Geographic variation in advertisement calls among populations of Dendropsophus cruzi (Anura: Hylidae) 

pp. 219-224

Authors: Geiziane Tessarolo, Natan Medeiros Maciel, Alessandro Ribeiro Morais & Rogério Pereira Bastos

Abstract: Anuran advertisement calls receive much attention because of their importance in mating behaviour and the recognition of conspecifics. Herein, we studied geographic variation in the advertisement call of Dendropsophus cruzi from central Brazil, to test the hypothesis that between-population differences in call parameters can be explained by geographical distance. We recorded 129 individuals from 10 populations of D. cruzi in Goiás State, Brazil, measuring call parameters of five calls of each individual. We found that dominant frequency is useful to distinguish populations, and that geographic distance is not a predictor of overall call differences. However, clinal geographical patterns were found for call duration, dominant frequency, call rate and snout-vent length (SVL). We suggest that differences in calls among populations can be due to local selective pressures.

 Key words: Anuran, dominant frequency, geographical patterns, isolation by distance

Online appendix for 06. Sexual dimorphism and interspecific head variation in the Liolaemus melanops complex (Squamata: Liolaemini) based on geometric morphometrics

pp. 225-235

Authors: Ignacio Minoli, M. Morando & Luciano J. Avila

Abstract: By analysing size and shape separately, geometric morphometric methods (GM) are a powerful tool to evaluate morphological differences within and between taxa. In this work, we used GM to investigate whether lizards of the Liolaemus melanops complex differ in shape and size. Specifically, we analysed head shape and size variation to quantify intraspecific sexual dimorphism and interspecific differences. We found sexual dimorphism in six of the seven investigated species (L. canqueli, L. dumerili, L. goetschi, L. martorii, L. melanops and L. morenoi). Five species (L. canqueli, L. casamiquelai, L. martorii, L. melanops and L. morenoi) were distinct in shape and size, whereas L. goetschi and L. dumerili were indiscernible from each other. This work illustrates the value of GM to study morphological variation in lizards, suggesting that similar studies would be valuable for testing species boundaries in other groups of Liolaemus.

Key words: Lizards, Liolaemus, morphological diversity, species' boundaries

Online appendix for 08. Spawning location is linked to the relative size of olfactory nerves in anurans

pp. 245-248

Authors: Qing Gui Wu, Shang Ling Lou, Yu Zeng & Wen Bo Liao

Abstract: The brain is the most important organ associated with demands on cognitive ability, and selection pressures have been implicated to explain variation in brain size and brain architecture in a wide range of taxa. Using phylogenetic comparative methods, we studied the effect of spawning location (terrestrial, lentic and lotic) on variation in the size of different brain parts among 43 Chinese anuran species. Spawning location was not significantly associated with relative brain size, and there were no links between spawning location and independent contrasts in size of the olfactory bulbs, telencephalon, optic tecta and cerebellum. However, the independent contrasts in size of the olfactory nerves differed significantly among the three types of spawning location. Our findings provide evidence that the brain structures underlying olfaction are linked to life history attributes required for spawning in specific habitat types.

Key words: anurans, comparative method, olfactory nerves, spawning location

pp. 249-252

Authors: Cheng Chen, You You Huang & Wen Bo Liao

Abstract: Variation in temperature and breeding season length caused by altitude has long been considered a major influence on the evolution of life-history traits in amphibians. Here, we examined differences in reproductive investment (testes mass and sperm length) of male spot-legged treefrog (Polypedates megacephalus) from two altitudes (680 m and 1300 m above sea level) in Guizhou Province, western China. Relative testes size from the high-altitude population was larger than that of the low-altitude population, whereas sperm length exhibited a converse cline. Testes mass but not sperm length increased with body size at both altitudes. Our findings suggest that differences in reproductive traits between populations might result from differences in the level of sperm competition.

Key words: Altitude, life history, Polypedates megacephalus, sperm length, testes size