Arterial supply of the choriocapillaris of anuran amphibians (Rana temporaria,Rana esculenta)

Summary The pattern of the vascular supply to the choroid of the frog eye was studied in toto with the use of the injection-replication-SEM technique. The choroid of anuran amphibians is composed mainly of the choriocapillaris. In both species studied (Rana temporaria, Rana esculenta), an independent arterial supply to the choriocapillaris supplemented that from the ciliary arteries. This additional vascular route arises from the optic artery, a separate branch of the arteria infundibularis superficialis. The optic artery, accompanied by its vein within the vascular sheath of the optic nerve, joins the rich arterial capillary network of the choriocapillaris and supplies the posterior pole of the ocular bulb. The superficial capillary network displays a dense collar around the entrance of the optic nerve into the eye and is composed of a circular meshwork of small capillaries, several layers deep. More peripherally, however, it becomes single layered. This capillary network, as a whole, establishes numerous connections with the adjacent choriocapillaris at the posterior pole of the ocular bulb. In anuran amphibians the complex arrangement of both arterial systems supporting the choriocapillaris may be regarded as a more complete equivalent of the short posterior ciliary arteries of mammals.     

Bioacoustic analysis of frog calls from northeast India

Mating calls of three frog species abundant in northeast IndiaRana tigerina,Rana cyanophlyctis andRana limnocharis were recorded in the fields of Assam and Meghalaya during their breeding season (July-August, 1991). The calls were analysed for their temporal and spectral characters. They were species specific, with distinct call duration and call period, number of pulses per call and interpulse interval, and dominant frequency and frequency domain. A comparison of the mating calls ofRana cyanophlyctis with those of the siblingRana ehrenbergi from Yemen showed differences in their temporal and spectral characters, supporting the suggestion that these two species are distinct species, rather than subspecies of the same species. Differences in the temporal and spectral pattern were found in the mating calls of morphologically alike specimens ofRana limnocharis, indicating that the present morphotypeRana limnocharis in northeast India is composed of several species.     

Character convergence in advertisement call and mate choice in two genetically distinct water frog hybridogenetic lineages (Rana kl esculenta, Rana kl grafi)

Patterns of advertisement call were investigated in two genetically distinct water frog lineages ( Rana kl esculenta, Rana. kl grafi ), which were identified by starch gel electrophoresis – the aim being to determinate the role of vocalization in the hybridogenetic process. Both hybrids displayed major modifications from the basic structure of the Rana ridibunda call. In Rana kl grafi , the call structure tended to correspond to that of Rana perezi in most of the studied parameters (frequency, duration, number of pulses) whereas the call of Rana kl esculenta tended to resemble that of Rana lessonae . The ascendant hierarchical classification clearly revealed such a convergence toward parental species and accounted for a divergence between hybrids. Changes in call patterns might result from both the expression of the non- ridibunda genome and the sexual selective pressure through female mate choice. Only few non- ridibunda females exhibited a preference for hybrid calls which, however, allowed some hybridogenetic males to obtain successful mates. Thus, hybridogenesis induced character convergence in courtship signal with the non- ridibunda species in hybrid zones. In any case, these changes in the courtship signal favoured the particular hybridogenetic process, which constitutes a quasi-parasitism of the non- ridibunda genome.     

Spatial variation in anuran richness,diversity, and abundance across montane wetland habitat in Volcanoes National Park,Rwanda

The spatial distribution of species has long sparked interest among ecologists and biogeographers, increasingly so in studies of species responses to climate change. However, field studies on spatial patterns of distribution, useful to inform conservation actions at local scales, are still lacking for many regions, especially the tropics. We studied elevational trends and species‐area relationships among anurans in wetland habitats within Volcanoes National Park (VNP) in Rwanda, part of the biodiverse Albertine Rift region. In VNP, wetlands are key sites for anuran reproduction, and anurans are likely threatened by wetland desiccation which has occurred for the last few decades. Between 2012 and 2017, we sampled anuran communities in ten VNP wetlands located along an elevational gradient of c. 600 m (from 2,546 to 3,188 m a.s.l.) and found at least eight species, including at least two Albertine Rift Endemics. We show that species richness, diversity, and abundance likely decline with a decrease in wetland size and with an increase in elevation, though additional sampling (e.g., at night) might be needed to derive definite conclusions. Larger wetlands at lower elevations contained most species and individuals, which indicates the potential threat of wetland size reduction (through desiccation) for anuran conservation. However, we also found that wetlands differed in species composition and that some species (e.g., Sclerophrys kisoloensis) were likely restricted in distribution to only a few of the smaller wetlands—suggesting that the conservation of each individual wetland should be prioritized, regardless of size. We propose that all wetlands in VNP require additional conservation measures, which should be based on knowledge gathered through long‐term monitoring of anuran communities and research on drivers of wetland decline. Only such extended research will allow us to understand the response of anurans in VNP to threats such as climate change and wetland desiccation.     

Speciation in the Rana chensinensis species complex and its relationship to the uplift of the Qinghai-Tibetan Plateau

Speciation remains a fundamental issue in biology. Herein, we report an investigation into speciation in the Rana chensinensis species complex using DNA sequence data from one mitochondrial and five nuclear genes. A phylogenetic analysis of the data revealed four major clades in the complex, and each of them was found to likely represent a species, including one cryptic species. Ecological niche models were generated from 19 climatic variables for three of the four major clades, which were represented by widespread sampling, including R. chensinensis, Rana kukunoris and the potential cryptic species. Each clade is associated with a unique ecological unit, and this indicates that ecological divergence probably drove speciation. Ecological divergence is likely related to the late Cenozoic orogenesis of the Qinghai–Tibetan Plateau. In addition, gene flow between species was detected but only in peripheral portions of the ranges of the four major clades, thus likely had little influence on the speciation processes. Discordances between mitochondrial and nuclear genes were also found; the nominal species, R. chensinensis, contains multiple maternal clades, suggesting potential mitochondrial introgression between R. chensinensis and R. kukunoris.     

Nematode lungworms of two species of anuran amphibians: evidence for co-adaptation

Genetic studies have indicated that some parasite species formerly thought to be generalists are complexes of morphologically similar species, each appearing to specialize on different host species. Studies on such species are needed to obtain ecological and parasitological data to address whether there are fitness costs in parasitizing atypical host species. We examined whether lungworms from two anuran host species, Lithobates sylvaticus and Lithobates pipiens, differed in measures of infection success in L. pipiens recipient hosts. We also determined if the worms from the two host species were sources of genetically resolvable species of morphologically similar nematodes. Sequences of internal transcribed spacer and lsrDNA regions of adult lungworms from each host species indicated that worms from L. sylvaticus matched Rhabdias bakeri, whereas worms from L. pipiens matched Rhabdias ranae. Our work suggested that these morphologically similar species are distant non-sibling taxa. We infected male and female metamorphs experimentally with lungworm larvae of the two species. We observed higher penetration, higher prevalence and higher mean abundance of adult worms in lungs of male and female metamorphs exposed to R. ranae larvae than in lungs of metamorphs exposed to R. bakeri larvae. Furthermore, metamorphs exposed to R. ranae larvae carried larger adult female worms in their lungs. Some variation in infection measures depended on host sex, but only for one parasite species considered. Overall, the differential establishment and reproductive potential of R. ranae and R. bakeri in L. pipiens suggests co-adaptation.     

Advertisement calls of the midwife toads Alytes (Amphibia, Anura, Discoglossidae) in continental Spain

The advertisement calls of six Spanish populations of midwife toads (genus Alytes) are described presenting characteristic audiospectrograms and oscillograms of the calls. Numerical data concerning the spectral and temporal features of the calls in relation to caller size (SVL) and temperature are also compared. The regression temperature vs. call duration groups the different populations according to the extant recognized phylogeny of the genus. Based on this character, the montane population of A. obstetricans from Penalara (Madrid) appears to be more closely related to the Pyrenean populations of A. o. almogavarü than to the more western populations of A. oboscai in Central Spain, which are closer geographically.     

Advertisement calls of the midwife toads Alytes (Amphibia, Anura, Discoglossidae) in continental Spain

The advertisement calls of six Spanish populations of midwife toads (genus Alytes ) are described presenting characteristic audiospectrograms and oscillograms of the calls. Numerical data concerning the spectral and temporal features of the calls in relation to caller size (SVL) and temperature are also compared. The regression temperature vs. call duration groups the different populations according to the extant recognized phylogeny of the genus. Based on this character, the montane population of A. obstetricans from Penalara (Madrid) appears to be more closely related to the Pyrenean populations of A. o. almogavarii than to the more western populations of A. o. boscai in Central Spain, which are closer geographically.

Zusammenfassung

Paarungsrufe der Geburtshelferköten Alytes (Amphibia, Anura, Discoglossidae) aus zentralspanischen Populationen
Die Paarungsrufe von sechs Geburtshelferkröten aus sechs spanischen Populationen werden hinsichtlich ihrer charakteristischen Tonfrequenz-Spektrogramme und Oszillogramme beschrieben.
Die numerischen Daten der spektralen und zeitlichen Eigenheiten der Rufmerkmale wurden mit der Größe der Männchen (SVL) und der Temperatur verglichen. Die Regression zwischen Temperatur und Dauer des Rufes ordnet die verschiedenen Populationen in der gleichen Weise ein, wie sie schon aus der allgemein anerkannten Phylogenetik der Gattung bekannt ist. Aufgrund dieser Untersuchungen, kann davon ausgegangen werden, daß die Gebirgspopulation A. obstetricans von Pealara (Madrid) enger mit der Pyrenäen-Population A. o. almogavarii verwandt ist als mit der westlichen Population A. o. boscai in Zentralspanien, obwohl sie zu jener geographisch näher liegt.     

六种共栖蝙蝠的回声定位信号及翼型特征的比较

本研究于2006 年5 ～ 8 月在桂林市七星公园七星岩洞进行,比较分析了共栖2 科(蹄蝠科和蝙蝠科)6 种共75 只蝙蝠的回声定位信号和翼型特征。普氏蹄蝠的回声定位叫声为短而多谐波的CF/ FM 型,主频率为61.2±0.8 kHz, 具有高翼载、低翼展比和中等翼尖指数; 大蹄蝠的回声定位叫声为单CF/ FM 型,主频率为68. 6 ±0.7 kHz,具有高翼载、低翼展比和中等翼尖指数;中蹄蝠的回声定位叫声为单CF / FM 型,主频率为85.2 ±0.5 kHz,具有中等翼载、低翼展比和中等翼尖指数;高颅鼠耳蝠的回声定位叫声为长带宽的FM 型,主频率为50.7 ±3.8 kHz,具有低翼载、中等翼展比和低翼尖指数;大足鼠耳蝠回声定位叫声为FM 型,主频率为39.9 ±3.2 kHz,具有中等翼载、低翼展比和高翼尖指数;绒山蝠回声定位叫声为短而多谐波的FM 型,主频率为49.0± 0. 4 kHz,具有高翼载、中等翼展比和低翼尖指数。经单因素方差分析表明,6 种蝙蝠之间绝大部分的形态和声音参数差异显著(One-way ANOVA,P < 0. 05)。以上结果说明,6 种同地共栖蝙蝠种属特异的回声定位叫声
和形态结构体现出了相互之间的生态位分离,从而降低了种间竞争压力,使得6 种蝙蝠能够同地共存。     

Disturbance calls of five migratory Characiformes species and advertisement choruses in Amazon spawning sites

Species-specific disturbance calls of five commercially-important characiform species are described, the Curimatidae commonly called branquinhas: Potamorhina latior, Potamorhina altamazonica and Psectrogaster amazonica; Prochilodontidae: jaraquí Semaprochilodus insignis and curimatã Prochilodus nigricans. All species have a two-chambered swimbladder and the sonic mechanism, present exclusively in males, utilises hypertrophied red muscles between ribs that adhere to the anterior chamber. The number of muscles is unusually plastic across species and varies from 1 to 4 pairs suggesting considerable evolution in an otherwise conservative system. Advertisement calls are produced in river confluences in the Madeira Basin during the high-water mating season (January–February). Disturbance calls and sampling allowed recognition of underwater advertisement choruses from P. latior, S. insignis and P. nigricans. The advertisement calls of the first two species have largely similar characteristics and they mate in partially overlapping areas in the Guaporé River. However, P. latior sounds have a lower dominant frequency and it prefers to call from river confluences whereas S. insignis shoals occur mostly in the main river channel adjacent to the confluence. These results help identify and differentiate underwater sounds and evaluate breeding areas during the courtship of commercially important characids likely to be affected by two hydroelectric dams.     

Identification of sympatric bat species by the echolocation calls

One hundred and thirty-eight echolocation calls of 63 free-flying individuals of five bat species (Rhinolophus ferrumequinum,Myotis formosus,Myotis ikonnikovi,Myotis daubentoni and Murina leucogaster)were recorded (by ultrasonic bat detector (D980)) in Zhi'an village of Jilin Province,China.According to the frequency-time spectra,these calls were categorized into two types:FM/CF (constant frequency) / FM (R.ferrumequinum) and FM (frequency modulated)(M.formosus,M.ikonnikovi,M.daubentoni and M.leucogaster).Sonograms of the calls of R.ferrumequinum could easily be distinguished from those of the other four species.For the calls of the remaining four species,six echolocation call parameters,including starting frequency,ending frequency,peak frequency duration,longest inter-pulse interval and shortest inter-pulse interval,were examined by stepwise discriminant analysis.The results show that 84.1% of calls were correctly classified,which indicates that these parameters of echolocation calls play an important role in identifying bat species.These parameters can be used to test the accuracy of general predictions based on bats' morphology in the same forest and can provide essential information for assessing patterns of bat habitat use.     

Identification of sympatric bat species by the echolocation calls

One hundred and thirty-eight echolocation calls of 63 free-flying individuals of five bat species (Rhinolophus ferrumequinum, Myotis formosus, Myotis ikonnikovi, Myotis daubentoni and Murina leucogaster) were recorded (by ultrasonic bat detector (D980)) in Zhi’an village of Jilin Province, China. According to the frequency-time spectra, these calls were categorized into two types: FM/CF (constant frequency) / FM (R. ferrumequinum) and FM (frequency modulated) (M. formosus, M. ikonnikovi, M. daubentoni and M. leucogaster). Sonograms of the calls of R. ferrumequinum could easily be distinguished from those of the other four species. For the calls of the remaining four species, six echolocation call parameters, including starting frequency, ending frequency, peak frequency duration, longest inter-pulse interval and shortest inter-pulse interval, were examined by stepwise discriminant analysis. The results show that 84.1% of calls were correctly classified, which indicates that these parameters of echolocation calls play an important role in identifying bat species. These parameters can be used to test the accuracy of general predictions based on bats’ morphology in the same forest and can provide essential information for assessing patterns of bat habitat use. __________ Translated from Journal of Northeast Normal University (Natural Science Edition), 2006, 38 (3): 109–114 [译自: 东北师范大学学报(自然科学版)]     

Evidence for two sympatric species of snipefishes<Emphasis Type="Italic"> Macroramphosus</Emphasis> spp. (Syngnathiformes,Centriscidae) on Great Meteor Seamount

About 202 specimens of snipefishes (Macroramphosus spp.) from Great Meteor Seamount (GMR, subtropical NE Atlantic, 30°N, 28.5°W) were analysed with respect to diet composition and morphology. Fifty specimens belonged to the deep-bodied benthos-feeding type (b-type) whose diet consisted of foraminifers, pteropods, decapods and polychaetes, whereas the slender planktivorous individuals (p-type, n=140) mainly fed on ostracods, copepods, pteropods and foraminifers. Twelve specimens showed no specialisation with respect to feeding (p/b-type). Both feeding types can be significantly distinguished from each other by means of bi- and multivariate morphological analysis considering the variables body depth, length of second dorsal spine, diameter of orbit and standard length. We discuss the hypothesis that M. gracilis represents a transient juvenile stage of M. scolopax. Since our specimens of the M. gracilis type were larger than specimens of the M. scolopax-type, such an ontogenetic shift is unlikely to occur. Our results support the hypothesis of Clarke for Australian snipefishes that for Macroramphosus spp. locally two distinct sympatric species must be anticipated, corresponding to M. scolopax and M. gracilis and the b- and p-types, respectively. Electronic Publication     

Double stimulation of the inner ear organs of an anuran species (Alytes cisternasii) with simple tonal advertisement calls

Midwife toads present one of the simplest calls in anurans, with the whole energy concentrated in a single band without frequency modulation. The tuning curves of the Iberian midwife toads Alytes cisternasii show the typical bimodal pattern in anurans, with two best excitatory frequencies at 0.412 kHz (corresponding to the amphibian papilla) and at 1.358 kHz (corresponding to the basilar papilla and matching the male call frequency). In this study, the hypothesis that complex calls arose in anurans because they were inherently more attractive to females, since they provided greater acoustic stimulation, was tested. However, our results indicate that splitting the call energy to stimulate both inner ear organs simultaneously, the male call is not more attractive to female midwife toads, but sometimes renders it unattractive. The biological role of the amphibian papilla is discussed in ecological and evolutionary terms.     

Distribution of anuran amphibians in massively altered landscapes in south-eastern Australia: effects of climate change in an aridifying region

Aim We explored whether the anuran amphibian faunas differed among landscapes that are relatively intact (largely covered in forests and woodlands) and others that are completely converted to agriculture. We also used historical data sets to assess the current condition of the anuran fauna in a region predicted to experience, and experiencing, severe drying and warming. Location Five pairs of landscapes (each of c. 20 km²) – one in each pair being almost completely wooded and the other cleared for agriculture – across a 30,000 km² region of northern Victoria, Australia. Methods Sites were repeatedly surveyed in the austral winter–spring breeding seasons of 2006 and 2007, with records collected of numbers of calling males and the presence of egg masses and tadpoles. We characterized the sites using static (e.g. dimensions, surrounding physiognomic characteristics such as tree cover) and labile (e.g. pH, dissolved oxygen) variables. Data were analysed using hierarchical Bayesian models. Results For calling males, landscape type did not affect densities or species richness measures. The availability of a grassy verge around water bodies was an important predictor for most species, but other labile and static variables seemed not to be important. Fewer than half of the species historically known from the region were recorded. There were no important predictors of occurrence of egg masses or tadpoles. Reproduction effectively may have failed over the period, with fewer than one in four sites showing evidence of egg masses or tadpoles. Main conclusions The proportion of sites at which some well‐studied species (e.g. Crinia signifera, Limnodynastes dumerilii) were recorded has dropped substantially since the 1970s, as have average densities of calling males of Crinia spp. The remnant anuran fauna appears to be dominated by resilient and hardy species with low current diversity. The on‐going (12+ years) drought in these landscapes suggests a bleak long‐term prognosis for the few remaining species of anuran amphibians.     

Evolution of intraspecific variation in the advertisement call of a cricket frog (Acris crepitans, Hylidae)

Advertisement calls of the cricket frog, Acris crepitans , show statistically significant variation among populations in all call variables measured. Call variables show strong clinal variation resulting in calls of lower frequency, longer duration and slower call rates produced by A. c. blanchardi in open habitat in the west of the range, and calls of higher frequency, shorter calls and faster call rates produced by A. c. crepitans in the pine forests in the eastern part of the range. This clinal variation does not result from pleiotropic effects of body size or any other morphological characters we measured.
The two subspecies usually reside in different habitats, but some A. c. blanchardi reside in an isolated pine forest in central Texas. By comparing the calls of this subspecies in open and forest habitat, and by statistically removing the effects of clinal variation for all populations, we determined that habitat explains some of the variation in call structure; this is not true of subspecies.
Our data reject several hypotheses that purport to explain the evolution of mate recognition signals. (1) We reject the notion of Paterson and others that there is strong stabilizing selection on species-specific mate recognition signals. (2) There is no support for the hypothesis that call variation is primarily due to pleiotropic effects of body size or other morphological characters over the geographic range we examined. (3) There is no evidence for reproductive character displacement. (4) Our data, as well as experimental studies of habitat acoustics, support the hypothesis that some differences in calls among habitats result from environmental selection on call structure to enhance call transmission. We suggest that the latter hypothesis does not explain the strong clinal component of call variation. This might result from the passive effects of gene flow between populations at the extremes of the range under selection generated by habitat acoustics.     

Vocalization of Hylodes meridionalis (Mertens 1927) (Anura,Hylodidae) in Rio Grande do Sul,Brazil, with comments on nocturnal calling in the family Hylodidae

We describe the advertisement and territorial calls of Hylodes meridionalis for the first time and provide observations on nocturnal calling activity for this species. The advertisement call has 36–82 harmonic notes, with duration of 2.71–5.69 s and dominant frequency on the third harmonic. Advertisement calls are separated by large intervals varying from 18.7 to 44.7 s. The territorial call has 1–3 notes, with duration of 0.039–0.567 seconds, and dominant frequency also on the third harmonic. Territorial calls are emitted at a much higher repetition rate than the advertisement call, with intervals of 1.1–1.6 s between each call. Frogs of the genus Hylodes are known to call mainly during the day, but for H. meridionalis nocturnal calling was observed on various occasions, and could occur regularly until two hours after sunset, or sporadically along the night.

Descrevemos os cantos de anúncio e territorial de Hylodes meridionalis pela primeira vez e fornecemos observações sobre a atividade noturna de vocalização para esta espécie. O canto de anúncio tem 36–82 notas harmônicas, com duração de 2,71–5,69 segundos e frequência dominante no terceiro harmônico. Há grandes intervalos entre os cantos de anúncio, de 18,7–44,7 segundos. O canto territorial tem 1–3 notas, com duração de 0,039–0,567 segundos, e frequência dominante também no terceiro harmônico. Cantos territoriais são emitidos a uma taxa de repetição muito mais elevado do que o canto de anúncio, com intervalos de 1,1–1,6 segundos entre cada canto. As espécies do gênero Hylodes são conhecidas por vocalizar principalmente durante o dia, mas machos de H. meridionalis foram observados em atividade de vocalização noturna em várias ocasiões, sendo que podem vocalizar regularmente até duas horas após o pôr do sol, ou esporadicamente ao longo da noite.