Taxonomy and Stratigraphy of Late Mesozoic Anurans and Urodeles from China

Three anurans (Callobatrachus sanyanensis, Liaobatrachus grabaui, Mesophryne beipiaoensis) and six urodeles (Laccotriton subsolanus, Liaoxitriton zhongjiani, Jeholotriton paradoxus, Sinerpeton fengshanensis, Chunerpeton tianyiensis, Liaoxitriton daohugouensis) are reported from the late Mesozoic tuff-interbedded lacustrine deposits (mostly of the Jehol Group) in northeastern China. They document the first discovery of Chinese Mesozoic lissamphibians, and their old geological age, superb preservation condition, and large taxoncmic diversity are unique compared with other findings worldwide. The anurans occupy a higher evolutionary position than typical Jurassic taxa, supporting a post-Late Jurassic age of the fossil horizons. The urodeles all have unicapitate ribs, suggesting an evolutionary grade at the cryptobranchoid level, and are advanced in osteological features over non-urodeles from the Middle and Upper Jurassic in England and Central Asia. Some urodeles (Jeholotriton and Chunerpeton) exhibit neotenic features, representing the earliest occurrence among such findings. Six fossil horizons are rscognized for the known Chinese Mesozoic anurans and urodeles: the Daohugou fossil bed, the Dabeigou Formation, the Lujiatun Bed, Jianshangou Bed and Dawangzhangzi Bed of the Yixian Formation, and the Jiufotang Formation. As implied from the osteological and phylogenetical studies, the geological age of these anurans and urodeles is the Early Cretaceous.

A Review for Life-history Traits Variation in Frogs Especially for Anurans in China

Environmental variation can promote differentiation in life-history traits in species of anurans. Increased environmental stress usually results in larger age at sexual maturity, older mean age, longer longevity, slower growth, larger body size, and a shift in reproductive allocation from offspring quantity to quality, and a stronger trade-off between offspring size and number. However, previous studies have suggested that there are inconsistent geographical variations in life-history traits among anuran species in China. Hence, we here review the intraspecific patterns and differences in life-history traits（i.e., egg size, clutch size, testes size, sperm length, age at sexual maturity, longevity, body size and sexual size dimorphism） among different populations within species along geographical gradients for anurans in China in recent years. We also provide future directions for studying difference in sperm performance between longer and shorter sperm within a species through transplant experiments and the relationships between metabolic rate and brain size and life-history.

Acoustic characteristics of eight common Chinese anurans during the breeding season

Anurans often have species-specific vocalizations. To quantify and compare the characteristics of anuran calls in Gutianshan National Nature Reserve, Zhejiang Province, we recorded the advertisement calls of eight species belonging to four families （Ranidae, Microhylidae, Megophryidae and Bufonidae） from June to September 2012 using Sony ICD-FX8 IC recorders. All recordings were analyzed using the ＂Praat＂ software. Five acoustics parameters were measured, including temporal traits （call duration, number of notes or pulse number/call） and spectral traits （fundamental frequency, the first three formants and dominant frequency）. The characteristic parameters of Microhyla ornate and Fejervarya limnocharis calls were different as were the calls of some populations of the same species recorded in different regions. The advertisement calls of the eight species were specific. Our study has provided a useful reference for identifying the calls of some common Chinese anurans.

Ecological and Geographical Reasons for the Variation of Digestive Tract Length in Anurans

Changes of environmental conditions can shape organs size evolution in animal kingdoms. In particular, environmental changes lead to difference in food resources between different habitats, thereby affecting individual’s energy intake and allocation. The digestive theory states that animals consuming food with low contents of digestible materials should result in increasing gut length. In this study, to test the hypothesis of digestive theory, we studied ecological and geographical reasons for variation in digestive tract length among 35 species of anurans distributing in different altitude and latitude. The results showed that ecological type significantly affected digestive tract length among species, with aquatic and terrestrial species having longer digestive tract than arboreal ones. Latitude was positively correlated with digestive tract length. However, altitude, as well as monthly mean temperature and precipitation, did not correlate with digestive tract length among species. Our findings suggest that aquatic and terrestrial species might forage less digestible materials than arboreal species, thereby displaying relatively longer digestive tract than arboreal species.

Cerebrovascularβ-dystroglycan immunoreactivity in vertebrates:not detected in anurans and in the teleosts Ostariophysi and Euteleostei

The aim of the present paper was to check for the presence of cerebrovascular dystroglycan in vertebrates,because dystroglycan,which is localized in the vascular astroglial end-feet,has a pivotal function in glio-vascular connections.In mammalian brains,the immunoreactivity ofβ-dystroglycan subunit delineates the vessels.The results of the present study demonstrate similar patterns in other vertebrates,except for anurans and the teleost groups Ostariophysi and Euteleostei.In this study,we investigated 1 or 2 representative species of the main groups of Chondrichthyes,teleost and non-teleost ray-finned fishes,urodeles,anurans,and reptiles.We also investigated 5 mammalian and 3 bird species.Animals were obtained from breeders or fishermen.The presence ofβ-dystroglycan was investigated immunohistochemically in free-floating sections.Pre-embedding electron microscopical immunohistochemistry on Heterodontus japonicus shark brains demonstrated that in Elasmobranchii,β-dystroglycan is also localized in the perivascular glial end-feet despite the different construction of their blood-brain barrier.The results indicated that the cerebrovascularβ-dystroglycan immunoreactivity disappeared separately in anurans,and in teleosts,in the latter group before its division to Ostariophysi and Euteleostei.Immunohistochemistry in muscles and western blots from brain homogenates,however,detected the presence ofβ-dystroglycan,even in anurans and all teleosts.A possible explanation is that in the glial end-feet,β-dystroglycan is masked in these animals,or disappeared during adaptation to the freshwater habitat.

Calls of the Large Odorous Frog(Odorrana graminea)Show Nonlinear and Individual Characteristics

Male large odorous frogs(Odorrana graminea)have been shown to have a rich vocal repertoire and their calls contain harmonics that extend into the ultrasonic range,much like calls of male O.tormota,a sympatric species.Whereas vocalizations of male O.tormota exhibit nonlinear characteristics and contain individual signatures,it is unclear whether or not those of O.graminea do.We carried out an extensive study of the vocalizations of male O.graminea with the goal of investigating whether they:(1)contained nonlinear phenomena(NLP),(2)carried individual signatures.We recorded and analyzed 1770 vocal calls from nine males.Their calls were classifiable into two distinct categories(one-note calls and multi-note calls).Of these,one-note complex/steep-frequency modulation call was the most abundant call-type.These calls showed diverse frequency modulation patterns,and abundant presence of NLP.Various basic spectral and temporal pa ra meters of such calls were individually distinct.Kruskal-Wallis Analysis of Rank test showed that the calls from individual males differed significantly.Subsequent discriminant function analysis(DFA)showed that 54.7%of the calls could be correctly assigned to individual.These results suggested that male O.graminea might be able to discriminate neighboring frogs from strangers acoustically.However,further research is necessary to demonstrate this capacity behaviorally.

Call Characteristic Network Reveal Geographical Patterns of Call Similarity:Applying Network Analysis to Frog’s Call Research

Individual’s phenotypic traits are the results of adaptation to ecological conditions.Therefore,different selection pressures caused by heterogeneous environments may result in phenotypic difference,especially for individuals in different geographical populations.Here,we illustrated for the first time to use social network analysis(SNA)for examining whether geographical proximity predicts the similarity patterns in call characteristics among populations of an anuran species.We recorded calls from 150 male dorsal-striped opposite-fingered treefrogs(Chiromantis doriae)at 11 populations in Hainan Province and one population in Guangdong Province in China's Mainland,and we measured eight acoustic variables for each male.Mantel test didn’t show a correlation between geographical proximity and the similarity in call characteristics among populations.In addition,we failed to find correlations between a population’s eigenvector centrality and the distance to its nearest neighbor,nor between the coefficient of variation of similarity in call characteristics of a population and the average distance to all other populations.Nevertheless,three acoustic clusters were identified by the Girvan-Newman algorithm,and clustering was partially associated with geography.Furthermore,the most central populations were included in the same cluster,but the top betweenness populations were located within different clusters,suggesting that centrality populations are not necessary bridging between clusters.These results demonstrate the potential usefulness of the SNA toolbox and indicate that SNA helps to uncover the patterns that often overlooked in other analytical methods.By using SNA in frog’s call studies,researchers could further uncover the potential relationship in call characteristics between geographical populations,further reveal the effects of ecological factors on call characteristics,and probably enhance our understanding of the adaptive evolution of acoustic signals.

Species Account of Anura ns from the Western Slope of Mt. Kita nglad, Mindanao Island, Philippines

The Mt. Kitanglad Range is one of the country’s important key biodiversity sites;however, information about anuran diversity in this protected area remains depauperate. Herein we provided accounts of anuran species from high-elevation forests, in three sites of the western slope of Mt. Kitanglad range. The combined belt-transect sampling and microha bitat searches accounted for 13 species representing five families. The most represented family was Rhacophoridae with five representative species of the genus Philautus. Twelve out of the 13 species documented in the current survey are endemic. Four previously unaccounted species(Pelophr yne brevipes, Pulchrana grandocula, Sanguirana mearnsi, and Philautus surrufus) were added and brought the total anurans known from Mt. Kitanglad to 26 species. Most of the species were also recorded in forested sites, suggestive of their lesser affinity to non-forested ecosystems. The additional species detected during our survey may also imply that full understanding of anuran diversity of Mt. Kitanglad remains far from complete.

Changes on Anuran Tadpole Functional Diversity along an Environmental Gradient at the Southernmost Atlantic Rainforest Remnant

For decades the ecologists are using the same methods in order to determine the environmental health of a community,however,the crescent need on defining how these processes act,triggered the development of new methods that could classify the organisms and their function at the habitats.Here we used the anuran larvae to understand the effects of an environmental gradient on the structure and organization of the anuran assemblages along it,and to access in a realistic form,the actual state of preservation of the la rgest remnant of Atlantic Rainforest on the Southernmost portion of Brazil.We found that despite the higher diversity of species and the conservation unit status of the place,the ecosystem itself is still in danger,given the low number of functional groups and thus a higher number of ecosystem services that can be lost.

Perception and Recognition of Vocalization in Anuran Mate Choice

Vocal communications in frogs and toads have been highly diversified and become a hot topic in the fields of herpetology,ecology,and behavioral neuroscience.The present short review summarized several interesting phenomena of vocal communication found mainly in anurans that might contribute to the individual identification of mates or rivals,including call matching,aggressive signaling,acoustic complexity,signal exaggeration,the first note effect and left hemisphere dominance.Investigations on the perception and recognition of vocal communications will facilitate our comprehension of the adaptive mechanisms and evolutionary paths of anuran signaling systems.We proposed here that comparative studies on acoustic signal structures,codes of sender status,and auditory neural responses based on phylogenetic relationships across species can highlight further the evolutionary trajectory in anurans.

Soundscape Dynamics at Anuran Reproductive Sites in Pannonian Biogeographical Region：Effects of Road Noise on Vocal Activity

The emerging field of soundscape ecology views ecosystems in terms of biophony, geophony and anthrophony. Soundscape ecology considers the effects of sound on fauna, and this research focuses on anuran breeding lek soundscapes. The sensitivity of anuran breeding leks to acoustic disturbances makes breeding leks an important venue for a comparative soundscape study. We made long-term（〉 24 h） sound recordings in three representative wetlands and short-term（〈 30 min） recordings in ten sites in the Pannonian Biogeographical Region of Hungary and around the Hungary and Slovakia border. Long-term soundscapes of the floodplain stretch, where there is relatively minor anthrophonical disturbance, showed an obvious circadian change in sound intensities. The site with moderate sound contamination exhibited a disturbed pattern of circadian sound variation, while the site with heavy traffic noise displayed an apparently random temporal soundscape. At different amphibian breeding sites during mating season, our short-term recordings were dominated by anuran calls, bird songs and wind noises, while insect calls and rain were present to a lesser degree. Our study indicates that vehicle traffic noise is a severe imposition to the natural soundscape, and suggests that soundscape monitoring can provide a reliable and sensitive index of environmental change for both short-term and long-term periods.

Spring Voices in Korean Rice Fields:The Effect of Abiotic Variables and Syntopic Calls on the Calling Activity of the Treefrog Dryophytes suweonensis

The calling activity of anurans is influenced by environmental variables and calls produced by syntopic amphibians,among other variables.Some variables have a strong influence,such as temperature and predation dilution,while others may have a periodical influence such as the moon cycle.Here,we hypothesised that the calling activity of the Suweon treefrog,Dryophytes suweonensis,is restricted by specific environmental variables but reinforced by the calling activity of specific syntopic anurans.Within the criteria set by the experimental design,D.suweonensis calling activity was significantly influenced by moon phase,temperature,date,time to sunset and the calling activity of Pelophylax nigromaculatus and D.japonicus.These variables are expected to be related to chorus size,predation,breeding phenology and competition,suggesting a broad plasticity in the calling activity of the species.

Acoustic Characteristics of Advertisement Calls in Babina adenopleura

Acoustic communication is the most important form of communication in anuran amphibians. To understand the acoustic characteristics of male Babina adenopleura, we recorded advertisement calls and analyzed their acoustic parameters during the breeding season. Male B. adenopleura produced calls with a variable number of notes（1–5）, and each note contained harmonics. Although 6% of call notes did not exhibit frequency modulation（FM）, two call note FM patterns were observed：（1） upward FM;（2） upward–downward FM. With the exception of 1- and 5- note calls, the duration of successive notes decreased monotonically. With the exception of 1 note calls, the fundamental frequency of the first note was lowest, then increased; the greatest change in the fundamental frequency was always between notes 1 and 2. The dominant frequency varied between calls. For example for the first call note the dominant frequency occurred in some cases in the first harmonic（located in the 605.320 ± 64.533 Hz frequency band）, the second harmonic（918 ± 9 Hz band）, the fourth harmonic（1712 ± 333 Hz band）, the sixth harmonic（the 2165 ± 152 Hz band）, the seventh harmonic（the 2269 ± 140 Hz band）, the eighth harmonic（the 2466 ± 15 Hz band） or the ninth harmonic（the 2636 ± 21 Hz band）. Although male B. adenopleura advertisement calls have a distinctive structure, they have similar characteristics to the calls of the music frog, B. daunchina.

Artificial light at night decreases the pupillary light response of dark-adapted toads to bright light

Artificial light at night(ALAN)is expanding worldwide.Many physiological effects have been reported in animals,but we still know little about the consequences for the visual system.The pupil contributes to control incoming light onto the retina.Sudden increases in light intensity evokes the pupil light reflex(PLR).Intrinsically photosensitive retinal ganglion cells(ipRGC)affect PLR and melatonin expression,which largely regulate circadian rhythms and PLR itself.IpRCG receive inputs from various photoreptors with different peak sensitivities implying that PLR could be altered by a broad range of light sources.We predicted ALAN to enhance PLR.Contrary to our prediction,dark-adapted cane toads Rhinella marina,exposed to ALAN(5 lx)for 12 days,exhibited a lower PLR than controls and individuals exposed to 0.04 lx,even after 1 h in bright light.We cannot conclude whether ALAN induced a larger pupil size in dark-adapted toads or a slower initial contraction.Nevertheless,the response was triggered by a light source with an emission peak(590 nm)well above the sensitivity peak of melanopsin,the main photoreceptor involved in PLR.Therefore,ALAN alters the capacity of toads to regulate the incoming light in the eye at night,which may reduce the performance of visually guided behaviors,and increase mortality by predators or road kills at night.This first study emphasizes the need to focus on the effect of ALAN on the vision of nocturnal organisms to better understand how this sensory system is altered and anticipate the consequences for organisms.

Geographical variation of the acoustic signals in the spot-legged treefrog (Polypedates megacephalus) of Hainan Island

Geographical divergence in acoustic signals is often affected by multiple selective pressures.Environmental factors are expected to shape signals by adjusting for greater propagation efficiency.Nevertheless,such habitat-driven hypotheses have not been well-examined with multi-signal and multi-habitat types included simultaneously.In this study,we evaluated call similarity of the spot-legged treefrog(Polypedates megacephalus),characterized by multiple call types,from 11 geographic populations across Hainan Island.We also examined multiple factors(i.e.body mass,temperature,altitude,and vegetation)among different acoustical geographic clusters,and tested whether the variation in acoustic length and frequency among different habitats was in accordance with the predic-tion derived from the acoustic adaptation hypothesis.We showed that P.megacephalus from Hainan Island included 3 acoustic geographic clusters:the northeasternflatlands,the southwest mountains,and the hills around the moun-tains.We also showed that environmental factors(i.e.altitude and vegetation)varied across these 3 acoustically distinct areas.Moreover,the duration of the different call types supported the hypothesis that they should have opti-mal transmission in their own habitats.Thus,our results reveal the roles of ecological selection in the geographical divergence of anuran acoustic signals.

Behavioral and neural auditory thresholds in a frog

Vocalizations play a critical role in mate recognition and mate choice in a number of taxa, especially, but not limited to, orthopterans, frogs, and birds. But receivers can only recognize and prefer sounds that they can hear. Thus a fundamental question linking neurobiology and sexual selection asks-what is the threshold for detecting acoustic sexual displays? In this study, we use 3 methods to assess such thresholds in tdngara frogs: behavioral responses, auditory brainstem responsesz and multi unit electrophysiological recordi ngs from the midbrain.We show that thresholds are lowest for multiunit recordings (ca. 45 dB SPL), and then for behavioral responses (ca. 61 dB SPL), with auditory brainstem responses exhibiting the highest thresholds (ca. 71 dB SPL). We discuss why these estimates differ and why, as with other studies, it is unlikely that they should be the same. Although all of these studies estimate thresholds they are not measuring the same thresholds;behavioral thresholds are based on signal salienee whereas the 2 neural assays estimate physiological thresholds. All 3 estimates, however, make it clear that to have an appreciation for detection and salienee of acoustic signals we must listen to those signals through the ears of the receivers.

Anuran interorbital distance variation:the role of ecological and behavioral factors

Eye position varies significantly among taxonomic levels,and this variation is often shaped by ecological and behavioral factors.Eye position is often positively associated with interorbital distance where species with broad visualfields possess a large distance between the left and right eye.Selective pressures underlying the evolution of the eye position are especially studied in birds and mammals.However,selective pressures underlying the evo-lution of anuran eye position which can be indicated by interorbital distance keep unknown.Here,we investigated the effects of ecological(e.g.habitat type,light availability)and behavioral factors(e.g.activity pattern,foraging mobility,and defensive strategy)on variations in interorbital distance among 260 anuran species in China.Our results showed that variations of the interorbital distance can be significantly predicted by the activity pattern.Noc-turnal species had larger interorbital distance than both nocturnal and diurnal species.We also found that foraging mobility and defensive strategy markedly affected variation of interorbital distance.Species having slower foraging mobility and possessing poison glands had larger interorbital distance than species having faster foraging mobility and possessing non-position glands.Light availability tended to be associated with variation of interorbital distance,indicating that species living in weak light tended to possess larger interorbital distance.However,variations of the interorbital space were not associated with habitat type in anurans.Ourfindings suggest that anuran behaviors play key roles in shaping visualfields and eye position,thus affecting the evolution of interorbital distance.

Sex and habitat differences in size and coloration of an amphibian’s poison glands match differential predator pressures

Chemical defenses are frequently accompanied by salient color patterns actively avoided by predators,a phe-nomenon referred to as aposematism.However,the production of both chemical defenses and pigments is costly,and is thus expected to be reduced under mild predator pressure.In this work,I compared the size and coloration of parotoid glands(2 dorsal,external swollen structures that secrete toxins in toads)of male and female Epidalea calamita toads from agrosystems and from pine groves.I also quantified the predator attacks received by plas-ticine toad models,whose“parotoid glands”differed in size and color conspicuousness,exposed in each habitat.Predators avoided models with large and conspicuous parotoid glands,but models in agrosystems were more of-ten attacked.Concerning actual toads,agrosystem and male individuals had larger parotoid glands,presumably implying greater production of chemical defenses than in pine grove and female conspecifics.Thesefindings are aligned with previous research suggesting that both agrosystem toads and males in this system are subjected to a more intense predator pressure.Difference between parotoid gland and dorsum coloration was greater in agrosys-tem toads.A marked internal pattern could function as an aposematic signal,which could counteract increased predator pressure.

Simulated predation pressure in Pelobates Cultripes tadpoles modulates morphology at the metamorphic stage

Studies on the impacts of variation of biotic interactions at key life cycle stages are crucial to understand the interface between ecological and developmental processes.Predators exert a major impact on prey fitness.Although direct consumption entails the greatest effect,predators can affect prey by means of other mechanisms.For instance,injuries inflicted by failed predation attempts can jeopardize prey fitness,even beyond the short-term.In anuran tadpoles,failed predation typically results in partial tail loss,which is known to reduce swimming speed.However,the potential consequences of tadpole partial tail loss after metamorphosis remain understudied.Because tail materials could be important in conforming metamorph body,we assess the effects of tadpole partial tail loss on metamorph body size in Iberian spadefoot toads Pelobates cultripes.We clipped 55%tail length of pre-tail-resorption stage anesthetized tadpoles,and compared their body size as metamorphs with anesthetized and non-anesthetized non-tail-clipped controls.Also,we tested whether tail length correlated with metamorph body size of individuals of the control groups.Tailclipped tadpoles produced smaller metamorphs than both controls(the bdy size of metamorphs from both controls was similar),which could incur costs in mid-term survival or time to first reproduction.This effect could be particularly important in areas with introduced predators,if autochthonous tadpoles lack defenses against them.Results suggest that materials resorbed from tadpole tail tissues might be reallocated into metamorph body,according to the negative effect of shorter tails in a correlational analysis,and clipped tails in an experimental test,on metamorph body size.

Morphology and mechanical performance between the skin surface of Rana dybowskii and Bufo gargarizans

Anuran skin is a typical natural biomaterial with multifunctional features.A specific comparison of mechanical performance and morphology related to them was performed in the skin of Rana dybowskii and Bufo gargarizans using the tensile testing technique and morphological equipment.Rana dybowskii's skin has soft smooth surface covered by polygonal epidermal cells,while the Bufo gargarizans species has tough and uneven skin surface due to numerous verrucae structures.The collagen fibre bundles in lower dermis of Bufo gargarizans have wavelike organisation while the bundles of Rana dybowskii show a parallel arrangement.The mean elastic modulus of Rana dybowskii was nine times higher than that of Bufo gargarizans.This study clarified that the arrangement of collagen fibres play an important role in the strength and elasticity of skin material.