Search

Frog diets are influenced by multiple factors, including morphological constraints, habitat use, and seasonal variation in environmental conditions and food availability. This study combined stomach content analysis (SCA), stable isotope analysis (SIA), and estimates of prey availability to investigate the influence of body size and microhabitat use on seasonal variation of the trophic ecology of two sympatric hylids (Pseudis minuta and Scinax squalirostris). We evaluated two hypotheses: (1) the species with larger body and mouth sizes or broader use of microhabitats will have greater diet breadth, and (2) regardless of differences in morphological traits and microhabitat use, diet breadth of both species will be greater during the warmer of two periods. Pseudis minuta exhibited larger body size and mouth width and revealed broader use of microhabitats (mostly within and near major water bodies), whereas S. squalirostris had smaller body size and mouth gape and was found exclusively within or near phytotelmata (plant-held water bodies). SCA revealed that P. minuta had a more diverse diet than S. squalirostris. Only P. minuta showed temporal dietary differences, but these findings did not corroborate our prediction of greater diet diversity during the warmer and drier period when prey densities were higher. The two species had distinct carbon and nitrogen stable isotope ratios, indicating assimilation of different resources, except during the colder wetter season when their isotope spaces overlapped partially. We concluded that the two hylids did not use the same food resources on account of their differences in morphology and microhabitat use, and environmental seasonality did not influence their feeding strategies. [ABSTRACT FROM AUTHOR]

The taxonomic status of some of New Zealand's endemic and threatened leiopelmatid frogs has been debated for decades. Clarifying this uncertainty is vital to their conservation, especially given the risk of extinction of cryptic taxa. We re-examined leiopelmatid diversity through multivariate analyses of the skeletal and external morphology of extinct and extant Leiopelma to determine morphological differentiation. Our results suggest that the morphological distinction between extinct taxa is greater than in modern extant taxa. While size ranges of postcranial elements overlapped within extant species, maxillae shape discriminated some extant taxa. We confirm the morphological distinctiveness of the extinct taxa recognized to date but identify latitudinal and altitudinal variation in postcranial element size and shape within the widespread Leiopelma markhami and L. waitomoensis, which suggest possible post-human extinction of cryptic taxa. Furthermore, the lack of morphological and osteological differentiation between L. archeyi and the insular extant L. hamiltoni and L. pakeka leads us to question the taxonomic distinctiveness of these three taxa. Future genetic research using modern and ancient DNA is recommended to enable species limits within Leiopelma to be tested in more detail to provide an evidence-based assessment for their conservation management. [ABSTRACT FROM AUTHOR]

Direct development has evolved independently several times in anurans and direct-developing species are characterized by large-scale developmental repatterning and a complete, or near complete, absence of most tadpole-specific structures. Earlier studies stressed the similarities among different direct-developing species, but more recent studies have indicated differences in the reduction of tadpole-specific structures among different taxa. Here, we describe egg deposition, clutch characteristics and embryonic development of the direct-developing squeaker frogs of the genus Arthroleptis, providing the first detailed description of direct development in Arthroleptidae. Embryonic development in Arthroleptis is characterized by the presence of an opercular fold that still encloses the developing forelimbs, the absence of external gills and an only moderately extended tail. A comparison with published information on other direct-developing anurans reveals broad dissimilarities in the formation of an opercular fold and very different tail morphology among different taxa. An egg tooth, often considered characteristic of direct-developing anurans, seems to be restricted to New World Terrarana. The embryonic diversity seen in direct-developing anuran taxa argues against simplistic assumptions about the evolution of direct development. [ABSTRACT FROM AUTHOR]

The European water frog ( Pelophylax esculentus) complex represents a unique and adequate model system for the study of interspecific hybridization and the mechanisms enabling interspecific hybrids to overcome the reproductive barriers. The difficulties in the study of individuals from the P. esculentus complex are associated with high polymorphism of morphological characters in parental species and interspecific hybrids, as well as with the presence of polyploid hybrid forms. From the discovery of the phenomenon of interspecific hybridization and the demonstration of successful reproduction of interspecific hybrids, researchers constantly searched for the methods necessary for the most accurate identification of parental species and various hybrid forms. This review describes biochemical, cytogenetic, and molecular methods and approaches used to identify individuals from the European water frog complex, as well as to analyze the genomes transferred with the gametes of hybrids. The advantages and disadvantages of these approaches are discussed. The presented methods can be used for studying other hybrid complexes of fish, amphibians, and reptiles. [ABSTRACT FROM AUTHOR]

Adaptations to captivity that reduce fitness are one of many reasons, which explain the low success rate of reintroductions. One way of testing this hypothesis is to compare an important behavioural response in captive and wild members of the same species. Thanatosis, is an anti-predator strategy that reduces the risk of death from predation, which is a common behavioral response in frogs. The study subjects for this investigation were captive and wild populations of Mantella aurantiaca. Thanatosis reaction was measured using the Tonic Immobility (TI) test, a method that consists of placing a frog on its back, restraining it in this position for a short period of time and then releasing it and measuring how much time was spent feigning death. To understand the pattern of reaction time, morphometric data were also collected as body condition can affect the duration of thanatosis. The significantly different TI times found in this study, one captive population with shorter responses, were principally an effect of body condition rather than being a result of rearing environment. However, this does not mean that we can always dismiss the importance of rearing environment in terms of behavioural skills expressed. [ABSTRACT FROM AUTHOR]

Network analyses have been increasingly used in the context of comparative vertebrate morphology. The structural units of the vertebrate body are treated as discrete elements (nodes) of a network, whose interactions at their physical contacts (links) determine the phenotypic modules. Here, we use the network approach to study the organization of the locomotor system underlying the hindlimb of frogs. Nodes correspond to fibrous knots, skeletal and muscular units. Edges encode the ligamentous and monoaxial tendinous connections in addition to joints. Our main hypotheses are that: (1) the higher centrality scores (measured as betweenness) are recorded for fibrous elements belonging to the connective system, (2) the organization of the musculoskeletal network belongs to a non-trivial modular architecture and (3) the modules in the hindlimb reflect functional and/or developmental constraints. We confirm all our hypotheses except for the first one, since bones overpass the fibrous knots in terms of centrality. Functionally, there is a correlation between the proximal-to-distal succession of modules and the progressive recruitment of elements involved with the motion of joints during jumping. From a developmental perspective, there is a correspondence between the order of the betweenness scores and the ontogenetic chronology of hindlimbs in tetrapods. Modular architecture seems to be a successful organization, providing of the building blocks on which evolution forges the many different functional specializations that organisms exploit. [ABSTRACT FROM AUTHOR]

Trophic differentiation of tadpoles of four anuran species (Hoplobatrachus rugulosus, Microhyla fissipes, M. heymonsi, Polypedates megacephalus) with different oral morphologies was studied in temporary ponds in a monsoon tropical forest in southern Vietnam. All tadpole species were found to be omnivorous, including filter-feeding microhylids. Both gut contents analysis and stable isotope analysis provided enough evidence of resource partitioning among coexisting species. Gut contents analysis supported the expected partitioning of food resources by tadpoles with different oral morphologies and showed differences in the food spectra of filter-feeding and grazing species. Stable isotope analysis revealed more complex trophic niche segregation among grazers, as well as amongst filter-feeders. Tadpole species differed mainly in d13C values, indicating a dependency on carbon sources traceable to either of aquatic or terrestrial origins. Furthermore, tadpoles with generalised grazing oral morphology (P. megacephalus) can start feeding as suspension feeders and then shift to the rasping mode. Controlled diet experiment with P. megacephalus larvae showed a diet-tissue isotopic fractionation of approximately 1.9‰ and 1.2‰ for Δ13C and Δ15N, respectively. In natural habitats, the difference in d13C and d15N values between body tissues and gut contents of four tadpole species averaged 2.8‰ and 1.0‰, respectively. [ABSTRACT FROM AUTHOR]

At least five different reproductive modes were reported in the neotropical frog genus Leptodactylus , all of them involving the building of foam nests. We analyzed the early ontogeny of five species of the L. fuscus group building terrestrial chambers where eggs are deposited, and of two species of the L. latrans group constructing a floating nest over the surface of lentic waters. The ontogenetic period described herein includes the occurrence of exclusively embryonic structures and the initial stages of development of larval features. In a likely relation to ecological aspects of oviposition and developmental mode, embryos of these two groups differ in several features. Embryos of the L. fuscus group were mainly pigmentless, were large sized with an extensive yolk provision, showed a dorsal kyphosis and lacked adhesive glands. Conversely, embryos of the L. latrans group were darkly pigmented, lacked a dorsal curvature, were comparatively smaller and less yolked, and showed adhesive glands in a peculiar type D morphogenetic pattern. Embryos of the L. latrans group had long, profusely branched, highly ciliated external gills, which were arranged ventrally. The comparative analysis of developmental sequences revealed an early emergence of hind limbs in Leptodactylus species relative to a reference leiuperine trajectory, an earlier differentiation of external gills in the species of the L. fuscus group, and an overall earlier development of mouthparts in embryos of the L. latrans group. Further analyses in a phylogenetic context are needed to evaluate the ancestral reconstructions of the development sequence and detect evolutionary relevant heterochronies in the genus. [ABSTRACT FROM AUTHOR]

Comparisons between populations that differ in resource availability and in environmental variables affecting the intensity of male–male competition allow insights into the mechanisms shaping reproductive allocation. Here, we studied inter-population variation in male investments in testis size and sperm length across four populations of the Yunnan pond frog ( Dianrana pleuraden ) along an altitudinal gradient in western China. Male body condition, relative testis size and sperm length did not increase with altitude despite an increasing male bias in the operational sex ratio (OSR) in high altitude was recorded. Our results were inconsistent with previous prediction that increasing latitude and/or altitude should lead to a declining male reproductive investment in anurans due to shortening breeding seasons and declining resource availability. We found a positive correlation between body condition and testes mass along the altitudinal gradient, which was indicative of a condition-dependent expression of testis size. By contrast, we recorded a non-significant correlation between testes mass and OSR, suggesting that male–male competition did not result in increasing levels of sperm competition. A non-significant correlation between sperm length and testis mass suggested that the intensity of sperm competition can account for the variation in sperm length. [ABSTRACT FROM AUTHOR]

A new species of Craugastoridae frog encountered from 1000-1700 m in elevation in the premontane forests of the Peruvian central Andes is described. The new species is similar in appearance to many other species of Pristimantis, but is easily distinguishable from these species by having bright red coloration on the groin, posterior surface of thighs, and shanks. The new species is only known for two localities 27 km apart in the Huánuco Region. [ABSTRACT FROM AUTHOR]

Bokermannohyla pseudopseudis is endemic to the Brazilian Cerrado, living in fast-flowing streams in the highlands of northern Goiás State, Brazil. Males have well-developed prepolexes and use steady pools in streams for reproduction, and therefore are likely territorial. Along with its small geographic distribution in high-altitude areas and habitat specialization it is a species at risk of extinction. Still, little is known about the ecology of B. pseudopseudis, hampering a correct evaluation of its conservation status and possible management strategies. We evaluated resource utilisation and sexual dimorphism in one population to test predictions related to territoriality and to evaluate diet specialization. We found a significant sexual size dimorphism, with males being larger than females, suggesting male-male competition. Males presented thicker forearms whereas females had proportionally longer heads. Tadpoles and calling males are found all year round, suggesting prolonged breeding activity, which is also in accordance with a resource defence breeding structure. Males and females did not select prey by size or volume, but males had wider niche breadths than females. Beetles, spiders, and cockroaches were the most relevant prey items, all of which are commonly found in the habitats of B. pseudopseudis. We emphasize that preservation of the habitats of B. pseudopseudis is essential to the management of the species because of its microhabitat restriction. [ABSTRACT FROM AUTHOR]

[Objective] This paper aimed to study the sexual dimorphism of Rana guentheri. [Method] Sixty-seven Rana guentheri were collected in Zhaoqing area to measure their morphological indexes, count the brood amount of female Rana guentheri and study sexual dimorphism and female reproductive characteristics. [Result] The average snout-vent length of male Rana guentheri was (75.07 ± 1.21) mm and the average snout-vent length of female Rana guentheri was (78.67 ± 1.23) mm. The snout-vent length and weight of female Rana guentheri were significantly different from that of male Rana guentheri, which illustrated that snout-vent length and body weight of Rana guentheri had significant sexual dimorphism. The sexual dimorphism index was 0.05. The local morphological indexes of Rana guentheri were positively related with the snout-vent length. The average brood amount of female Rana guentheri was 4916. The snout-vent length and body weight were positively related with the brood amount of female Rana guentheri. [Conclusion] Rana guentheri in Zhaoqing area had obvious sexual dimorphism. [ABSTRACT FROM AUTHOR]

Despite being common in the Western Ghats-Sri Lanka biodiversity hotspot, Golden-backed frogs (Hylarana, Ranidae) remain poorly studied. In this paper, we present some preliminary data on the morphology, behaviour, and habitat use of Hylarana intermedia, a member of the Hylarana aurantiaca species group. We find evidence for female biased size dimorphism, as well as potential shape differences between the sexes in this species. Additionally, we investigate the relationships between traits that may contribute to male conspicuousness (call rates, dorsal coloration, and body size) in two breeding habitats, a paddy field and a trench. Our results suggest both size-dependent and environment-dependent variation in call rate and colour in this species. Specifically, we find evidence against the adoption of sneaker mating strategies by small males in H. intermedia, and instead find variation both within and between populations in traits contributing to male conspicuousness. We conclude by proposing future directions for research on this common frog species. [ABSTRACT FROM AUTHOR]

The tadpole of Ptychadena uzungwensis is described from material collected at Mufindi, southern Udzungwa Mountains, Tanzania. We provide a detailed description of the tadpole based on an ontogenetic series, including color photographs of living specimens and buccopharyngeal morphology. Identity was confirmed by rearing tadpoles through metamorphosis and through DNA bar coding. The tadpole has a keratodont formula of 1/2 and generally resembles other species of Ptychadena. Diagnostic features of known tadpoles of East African species of Ptychadena are provided and discussed. [ABSTRACT FROM AUTHOR]

Many animals respond to predation risk by altering their morphology, behavior, or life-history. We know a great deal about the cues prey respond to and the changes to prey that can be induced by predation risk, but less is known about how plastic responses to predators may be affected by separate plastic responses occurring earlier in life, particularly during the embryonic period. Embryos of a broad array of taxa can respond to egg- or larval-stage risks by altering hatching timing, which may alter the way organisms respond to future predators. Using the red-eyed treefrog (Agalychnis callidryas), a model for understanding the effects of plasticity across life-stages, we assessed how the combined effects of induced variation in the timing of embryo hatching and variation in the larval predator community impacted tadpole morphology, pigmentation and swimming performance. We found that A. callidryas tadpoles developed deeper tail muscles and fins and darker pigmentation in response to fish predators, either when alone or in diverse community with other predators. Tadpoles altered morphology much less so to dragonfly naiads or water bugs. Interestingly, morphological responses to predators were also affected by induced differences in hatching age, with early and late-hatched tadpoles exhibiting different allometric relationships between tail height and body length in different predator environments. Beyond induced morphological changes, fish predators often damaged tadpoles’ tails without killing them (i.e., sublethal predation), but these tadpoles swam equally quickly to those with fully intact tails. This was due to the fact that tadpoles with more damaged tails increased tail beats to achieve equal swimming speed. This study demonstrates that plastic phenotypic responses to predation risk can be influenced by a complex combination of responses to both the embryo and larval environments, but also that prey performance can be highly resilient to sublethal predation. [ABSTRACT FROM AUTHOR]

Four species of endemic Leptobrachium are known from Borneo, two lowland species L. kanowitense and L. abbotti, a montane species L. montanum, and a highland species L. gunungense. Of these, bothL. montanum and L. abotti were found to contain several cryptic species by recent molecular studies. The population from Bario, Kelabit Highland of Sarawak, is one such cryptic species and was once called Lineage 2 of L. abbotti. Our morphological survey on this population proved that it has characteristics distinct from all other congeners, and therefore, we describe the Bario population as a new species, Leptobrachium kantonishikawai sp. nov. The new species is distinguished from putative topotypes of L. montanum and L. abbotti, as well as from L. gunungense by having a grayish brown abdomen, usually vermiculated, although sometimes spotted or blotched with white, and some unique morphometric characteristics. [ABSTRACT FROM AUTHOR]

Many clades contain ecologically and phenotypically similar species across continents, yet the processes generating this similarity are largely unstudied, leaving fundamental questions unanswered. Is similarity in morphology and performance across assemblages caused by evolutionary convergence or by biogeographic dispersal of evolutionarily conserved ecotypes? Does convergence to new ecological conditions erase evidence of past adaptation? Here, we analyse ecology, morphology and performance in frog assemblages from three continents (Asia, Australia and SouthAmerica), assessing the importance of dispersal and convergent evolution in explaining similarity across regions. We find three striking results. First, species using the same microhabitat type are highly similar in morphology and performance across both clades and continents. Second, some species on different continents owe their similarity to dispersal and evolutionary conservatism (rather than evolutionary convergence), even over vast temporal and spatial scales. Third, in one case, an ecologically specialized ancestor radiated into diverse ecotypes that have converged with those on other continents, largely erasing traces of past adaptation to their ancestral ecology. Overall, our study highlights the roles of both evolutionary conservatism and convergence in explaining similarity in species traits over large spatial and temporal scales and demonstrates a statistical framework for addressing these questions in other systems. [ABSTRACT FROM AUTHOR]

Currently there are only two recognized species in the genus Haddadus; however advertisement calls are known for neither of them. Herein, we describe the advertisement call of Haddadus binotatus from males recorded at the Serra Bonita reserve in the municipality of Camacan in southern Bahia, Brazil and provide morphometric data to allow further comparison with individuals from other localities. The advertisement call of the studied population can be characterized as short and low-pitched, with a low volume sound, consisting of a single note made up of 3-6 pulses and a length of 0.012-0.033 s. The dominant frequency ranges from 1033.6-1464.3 Hz. The SVL of males ranged between 32-38.6 mm and females between 50-55.8 mm. Females were significantly larger than males. Our data can help solving identity problems within this species, which is thought to be a species complex. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the reduction and development of the dark-sided frog Hylarana nigrovittata sensu in at the Cologne Zoo in northern Thailand. The study involves identification of oviposition which occurred in accordance with dried natural habitat, along with the Important factor to increase the reproduction in captivity, such as an increase in misting with combined raised water levels. Results show the molecular divergence and morphological differences regarding the captive breeding and development stages of the dark-sided frog.

The article reports on the morphological differences between breeding and non-breeding of Odorrana amamiensis commonly known as amami tip-nosed frog in both sexes which was found in Amami-Oshima Island.