Temporal selectivity for complex signals by single neurons in the torus semicircularis of Pleurodema thaul (Amphibia: Leptodactylidae)

Responses of auditory neurons in the torus semicircularis (TS) of Pleurodema thaul, a leptodactylid from Chile, to synthetic stimuli having diverse temporal patterns and to digitized advertisement calls of P. thaul and three sympatric species, were recorded to investigate their temporal response selectivities. The advertisement call of this species consists of a long sequence of sound pulses (a pulse-amplitude-modulated, or PAM, signal) having a dominant frequency of about 2000 Hz. Each of the sound pulses contains intra-pulse sinusoidal-amplitude-modulations (SAMs). Synthetic stimuli consisted of six series in which the following acoustic parameters were systematically modified, one at a time: PAM rate, pulse duration, number of pulses, and intra-pulse SAM rate. The carrier frequency of these stimuli was set at the characteristic frequency (CF) of the isolated units (n = 47). Response patterns of TS units to synthetic call variants reveal different degrees of selectivities for each of the temporal variables, with populations of neurons responding maximally to specific values found in the advertisement call of this species. These selectivities are mainly shaped by neuronal responsiveness to the overall sound energy of the stimulus and by the inability of neurons to discharge to short inter-pulse gaps. Accepted: 30 October 1996     

Sound-producing mechanisms and recordings in<Emphasis Type="Italic"> Carapini</Emphasis> species (Teleostei,Pisces)

Carapus boraborensis, C. homei and Encheliophis gracilis are three species of Carapidae that display the ability to penetrate and reside in the holothurian Bohadschia argus. This study describes both the particular morphology of the sound-producing structures and, for the first time, the sounds produced by each species. The study of the structures composing the sound-producing system seems to indicate that the action made by the primary sonic muscles (i.e. the pulling and releasing of the front of the swim bladder) might be responsible for the sound emissions of these three species by provoking a vibration of a thinner zone in front of the swim bladder (swimbladder fenestra). The sounds were only emitted and recorded when several individuals of the same species were inside the same sea cucumber. They were composed of serially repeated knocks and were heard as drum beats or drum rolls. Their specific differences were mainly defined as variations in the timing or grouping of the knocking sounds. The recordings of these sound productions demonstrate a vocal ability for the three species, linked with the presence of particular organs associated with sound production. Moreover, the ecological significance of the sounds and of the sound apparatus system is discussed.     

Sound production in two carapids (Carapus acus and C. mourlani) and through the sea cucumber tegument

Parmentier, E., Fine, M., Vandewalle, P., Ducamp, J.‐J. and Lagardère, J.‐P. 2006. Sound production in two carapids (Carapus acus and C. mourlani) and throught the sea cucumber teguments. —Acta Zoologica (Stockholm) 87 : 113–119 Carapus acus and Carapus mourlani are able to live inside sea cucumbers and sea stars respectively. Unlike other carapids whose sounds have been recorded (C. boraborensis, C. homei and Encheliophis gracilis), these two species have a central constriction in their swimbladder and are unlikely to encounter heterospecific carapids within their hosts. We evoked sound production in Carapus acus and Carapus mourlani by adding several individuals to a tank with a single host and found that their sounds differ substantially from the sounds emitted by other carapids in pulse length, peak frequency and sharpness of tuning (Q_3 dB). Unlike the other carapids, C. mourlani and C. acus produce shorter and less repetitive sounds and do not produce sounds when they enter their host. Since sounds produced within a sea cucumber have the potential to be heard by distant carapids and are typically recorded outside the sea cucumber, we examined the effect of the sea cucumber tegument on acoustic transmission. Attenuation by the tegument was negligible at the frequencies within carapid sounds. Therefore, carapids have the potential to call from the relative safety of a sea cucumber without sacrificing the distance over which their transmissions are heard.     

Phylogenetic analysis of the pearlfish tribe Carapini (Pisces: Carapidae)

Fishes of the tribe Carapini (Encheliophis and Carapus) share a noteworthy peculiarity: they shelter in holothurian echinoderms or bivalve hosts. Some species are considered parasitic, others commensal. This study focuses on the phylogeny of the tribe, using two other Carapidae species as an outgroup (Snyderidia canina and Onuxodon fowleri). Insofar as possible, the selected anatomical and behavioural characters where chosen in an ecomorphological perspective, as features that could be responses to various lifestyle‐related constraints. Our character selection also took into account the fact that some features are (presumably) linked. Such features were grouped together as a single trait to avoid their overvaluation. This methodology enabled commensals to be separated from parasites, the former belonging to Carapus and the latter to Encheliophis. Carapus species reflect in their morphology the constraints imposed by a diet of hard, mobile, elusive prey, showing predator‐type features: a strong dentition, a wide mouth opening, a robust food intake apparatus. On the other hand, the endoparasitic Encheliophis species show a generally weaker buccal apparatus and narrow mouth opening, in relation to the different constraints of their lifestyle where the diet constraints are less pronounced: they eat body parts of their host. Changes in both generic diagnoses are proposed and three species are transferred from Encheliophis to Carapus.     

Host‐specific morphologies but no host races in the commensal bivalve Neaeromya rugifera

Speciation by host shift is one of the explicit models of ecological speciation. A prerequisite of this model is the formation of host races (sympatric populations that show host‐specific genetic structuring and phenotypes). Many members of the diverse marine bivalve superfamily Galeommatoidea have obligate commensal relationships with invertebrate hosts. Some species have the ability to occupy multiple host species, thereby providing potential opportunities to test for the formation of host races. The Northeast Pacific galeommatoidean Neaeromya rugifera attaches to two strikingly different hosts: the blue mud shrimp Upogebia pugettensis and the polychaete sea mouse Aphrodita spp. We tested if this host difference has resulted in the formation of host races using shell morphologies and genetic markers. We found that populations from different hosts differ significantly in shell morphology. However, based on mitochondrial makers, N. rugifera showed no distinct host‐specific genetic structuring, indicating the existence of a panmictic population. We conclude that the host‐specific morphologies these clams exhibit may reflect ecophenotypic plasticity rather than the existence of host races, but this needs to be corroborated with additional genetic data and larger sample sizes. The pronounced conchological variation within N. rugifera calls for further investigation of its taxonomic relationship with its poorly studied, but morphologically similar, sympatric congener Neaeromya compressa.     

Interspecific responses to distress calls in bats (Chiroptera: Vespertilionidae): a function for convergence in call design?

Distress calls were recorded from three sympatric species of pipistrelle bat (Pipistrellus nathusii, P. pipistrellus and P. pygmaeus) in England and Northern Ireland. At foraging sites, we conducted playback experiments, consisting of experimental distress call sequences from each species and control sequences of random noise and sound recorded with no bats present. We measured response by simultaneously recording ultrasound during playbacks and counting the echolocation pulses above a predetermined threshold which were then identified to species. All three species responded to each other's calls. The number of recorded echolocation pulses of all species increased eight-fold, on average, during the playback of distress call sequences compared with the playback of ultrasonic noise, and four-fold compared with the playback of silence. In a separate playback experiment, the number of echolocation pulses of P. pygmaeus increased 14-fold during the playback of distress calls of four endemic species of bat from Madagascar (Emballonura atrata, Myotis goudoti, Miniopterus majori and M. manavi) compared with the playback of silence. This increased response might have been caused by the high calling rates of the Malagasy species. Distress calls of P. nathusii, P. pipistrellus and P. pygmaeus were structurally convergent, consisting of a series of downward-sweeping, frequency-modulated elements of short duration and high intensity with a relatively strong harmonic content. Selection may favour convergence in the structure of distress calls among bat species, if attracting heterospecifics increases the chance of repelling predators by mobbing.     

Temporal variability of settlement in Carapidae larvae at Rangiroa atoll

Carapidae (or pearlfish) are eel-like fishes living inside different invertebrates, such as holothurians, sea stars or bivalves. In some Polynesian areas where they live in sympatry, several species (Carapus homei, Carapus mourlani, Carapus boraborensis and Encheliophis gracilis) are able to inhabit the same host species. The heterospecific infestation rate is very rare, suggesting that the four species can compete for their hosts. Some differences in settlement period, breeding period and in pelagic larval duration (PLD) could allow better characterisation of the life history of each species. More than 700 larvae were collected during an entire year on the Rangiroa atoll (French Polynesia). Each species was identified; their settlement pattern was examined and their PLD was deduced from otolith (sagittae) increments. In the four collected species, the settlement pattern differed: C. homei and C. mourlani settle on the reef during the entire year, and show an asynchronous and diffuse breeding cycle. C. boraborensis and E. gracilis have a shorter settlement period which could be compatible with breeding synchronisation. As most reef fishes, Carapidae larvae mainly settle during moonless nights. Moreover, each species presents some plasticity, allowing it to settle on the reef under suitable conditions.     

Advertisement calls of two anuran amphibians,Rana tigrina andTomopterna breviceps

Rana tigrina andTomopterna breviceps occur as sympatric species at Dharwad, India. Sexually mature males produce advertisement calls. The advertisement call of both the species consist of a number of calls produced in series forming a call group. Each call group ofRana tigrina comprises 10–40 calls, whereas that ofTomopterna breviceps consists 13–141 calls. Each call consists of a pulse group with variable number of pulses which lack pulse interval. Calls of both the species exhibit similarities in (i) call consisting of series of calls with a pulse group in each call, (ii) absence of pulse interval within the pulse group, (iii) the amplitude of the first pulse being always small, and (iv) the frequency spectrum beginning from 200 Hz. Based on the similarities in the spectral features of the calls, it is suggested that the two species may be closely related to each other.     

INTRA- AND INTERSPECIFIC DIFFERENCES IN AGONISTIC VOCALIZATION IN CROAKING GOURAMIS (GENUS: TRICHOPSIS,ANABANTOIDEI, TELEOSTEI)

ABSTRACT

In this study a detailed analysis of acoustical parameters of sounds produced by male Trichopsis vittatus, T. schalleri and T. pumilus during agonistic behaviour is reported. The calls consist of croaks which are composed of double pulses generated by modified pectoral fins. Calls of the three species are different in main frequency, number of double pulses within a croak and double pulse period. Croaks are uttered in series only in T. vittatus. Sound pressure levels are highest in T. pumilus, the smallest species. Amplitude of individual pulses of a double pulse are similar in T. pumilus and T. schalleri. Main frequency is negatively correlated with body mass in all species, but there is no correlation between sound pressure level and body mass. Differences in the calls of the three species suggest that T. schalleri is a distinct species. Furthermore, results indicate spectral characteristics and sound intensity could be of biological importance in fish.     

Passive acoustic monitoring,development of disturbance calls and differentiation of disturbance and advertisement calls in the Argentine croaker Umbrina canosai (Sciaenidae)

Disturbance and advertisement calls of the Argentine croaker Umbrina canosai were recorded from coastal Uruguayan waters. Dissections indicate typical sciaenid extrinsic swimbladder muscles present exclusively in males. Disturbance calls were produced when captive U. canosai were startled, chased with a net or grabbed by the tail. Calls were unusual for sciaenids because each pulse consisted of multiple cycles. The number of cycles per pulse and dominant frequency did not change with U. canosai size, but pulse duration and interpulse interval increased. Advertisement calls were recorded from unseen choruses in the field and confirmed with captive individuals in a large tank. Advertisement calls were recorded throughout the known range of the species in Uruguay indicating a continuous belt of spawning populations. Tank recordings of the same individuals permitted explicit comparisons between the two calls. Advertisement call pulses averaged 2·4 more cycles (11·0–8·6) although pulses of both calls were basically similar as were durations and dominant frequencies. Pulse number, however, differed markedly, averaging 13·6 and 3·4 pulses for disturbance and advertisement calls respectively. Furthermore, disturbance calls were produced as a rapid series with an interpulse interval of 26–31 ms whereas advertisement call patterns were less stereotyped and ranged from <100 to 450 ms. Multicycle pulses distinguished U. canosai from other sympatric sciaenids.     

Acoustic Niches of Siberut Primates

The loud calls nonhuman primates use in long-distance communication have supposedly been selected for efficient information transfer in the habitat. The differential effects of scattering and reverberation and the masking effects of background noise predict that loud calls produced in rain forest habitats should be low-pitched and whistle-like with low-frequency modulation. Callers may also use particular calling posts or times of day with reduced background noise to increase the efficacy of sound transmission. We studied the loud calls of the 4 sympatric primate species on Siberut Island. Only Kloss gibbons (Hylobates klossii) fulfilled the predictions regarding both the structure and use of calls. Though the other 3 species —Mentawai macaques (Macaca siberu), pig-tailed langurs (Simias concolor), and Mentawai leaf monkeys (Presbytis potenziani)— also concentrated their main energies in the spectral window with the lowest background noise, their calls were not adapted to long-range transmission. All 4 species produced loud calls exclusively no lower than 18 m above ground, but food abundance and shelter in the canopy may also be factors. Though all 4 species produced the majority of loud calls in the morning, it was not the only time of day with reduced background noise. We suggest that phylogenetic inheritance may better explain the structure of calls than adaptation to the habitat. In sum, the observed usage of spectral and temporal niches is not solely an adaptation to the sound profile of the habitat, though it clearly improves their transmission.     

COMPACT DISC REVIEW

ABSTRACT

In previous studies, calling sites of two species of burrowing frogs Eupsophus in southern Chile have been shown to amplify conspecific vocalizations generated externally, thus providing a means to enhance the reception of neighbour's vocalizations in breeding aggregations. In the current study the amplification of vocalizations of Eusophus roseus was investigated to explore the extent of sound enhancement reported previously for two congeneric species. Advertisement calls broadcast through a loudspeaker placed in the vicinity of a burrow, monitored with small microphones, are amplified by up to 14 dB inside cavities relative to outside. The fundamental resonant frequency of burrows, measured with broadcast noise and pure tones, ranges from 345–1335 Hz; however it is not correlated with burrow length. The spectra of incoming calls are altered inside burrows by predominantly increasing the amplitude of lower relative to higher harmonics. The call amplification effect inside burrows of E. roseus parallels the effect reported previously for two congeneric species and reinforces the suggestion that sound enhancement inside calling sites has a widespread effect on signal reception by burrowing animals.     

Aspects of Species Recognition by Sound in Four Species of Damselfishes,Genus Eupomacentrus (Pisces: Pomacentridae)

Members of four sympatric species of Eupomacentrus carry out reproductive activities at the same time of the year and produce similar pulsed courtship sounds. Such sounds are known to facilitate courtship among conspecifics. Consequently, members of the four species in the field and in the laboratory were tested with the various sounds to determine if they could distinguish their own species sounds from those produced by congeners. The differential responses clearly demonstrate species specific recognition by sound and indicate that the pulse interval and the number of pulses per sound are the important parameters for this recognition.     

Heterospecific Vocal Interactions in a Frog from the Southern Temperate Forest,Batrachyla taeniata

Animals using sound communication employ different strategies to overcome interferences from biotic and abiotic sources. However, interactions among acoustically active species have been studied to a very limited extent. The evoked vocal responses of 20 male frogs Batrachyla taeniata from the temperate austral forest in Chile were tested with conspecific calls and with the calls of two sympatric species: B. antartandica and B. leptopus, broadcast at amplitudes of 73, 79, 85, 91 and 97 dB peak SPL. The subjects responded actively to the conspecific call, but only responded weakly to the call of B. leptopus at the highest intensity. The preferential responses to conspecific calls could contribute to the typical segregation in monospecific choruses observed in areas where these frogs breed in sympatry.     

Sympatry and interference of divergent Microbotryum pathogen species

The impact of infectious diseases in natural ecosystems is strongly influenced by the degree of pathogen specialization and by the local assemblies of potential host species. This study investigated anther‐smut disease, caused by fungi in the genus Microbotryum, among natural populations of plants in the Caryophyllaceae. A broad geographic survey focused on sites of the disease on multiple host species in sympatry. Analysis of molecular identities for the pathogens revealed that sympatric disease was most often due to co‐occurrence of distinct, host‐specific anther‐smut fungi, rather than localized cross‐species disease transmission. Flowers from sympatric populations showed that the Microbotryum spores were frequently moved between host species. Experimental inoculations to simulate cross‐species exposure to the pathogens in these plant communities showed that the anther‐smut pathogen was less able to cause disease on its regular host when following exposure of the plants to incompatible pathogens from another host species. These results indicate that multi‐host/multi‐pathogen communities are common in this system and they involve a previously hidden mechanism of interference between Microbotryum fungi, which likely affects both pathogen and host distributions.     

A Comparison of Four Vocalizations of the Genus Tragopan (Aves,Phasianidae)

Four calls of the genus Tragopan were described and acoustically analysed. Alarm and wing whir calls were very similar in sound and structure in all five species. By contrast, a comparison of 11 physical parameters of advertisement and clicking calls indicated that species separated into three groups: western and Cabot's each separated into their own group, whereas Blyth's, Temminck's and satyr formed another group. It was hypothesized that the tragopan prototype population had their origin in the eastern Himalayas. Thus, the centrally distributed species of tragopans (satyr, Blyth's and Temminck's) retained characteristics of the ancestral population, whereas the peripheral species (western and Cabot's) underwent vocal modifications. Courtship vocalizations, which are under sexual selection pressure, probably serve as species-isolating mechanisms in sympatric species.     

On the genetic diversity in the mitochondrial 12S rRNA gene of Platymantis frogs from Western New Guinea (Anura: Ceratobatrachidae)

Platymantis is a group of neobatrachian frogs that occurs from the Philippines to New Guinea – an area situated at the interface between the Australian and Asian biogeographical region that is highly fragmented by stretches of open sea. Partial sequences of the mitochondrial 12S rRNA gene are herein used to infer the relationships of species from the Indonesian part of New Guinea (Papua and West Papua Province). The phylogenetic trees reveal a deep bifurcation between the Asian and Western New Guinean clades being consistent with phylogeographic patterns observed in various other faunal groups. While most species are well differentiated in the examined locus, low interspecific genetic distances between one and three percent were observed in the New Guinean species Platymantis papuensis and P. cryptotis as well as P. pelewensis from Palau. Platymantis papuensis and P. pelewensis are geographically separated from each other by a 1100 km stretch of open sea. The minor degree of genetic differentiation between both species points to a recent event of transmarine dispersal as causation for the occurrence of P. pelewensis on Palau. The low genetic differentiation between P. cryptotis and the sympatric P. papuensis, two species that are bioacoustically and morphologically distinct, may indicate its possibly recent evolutionary origin or, alternatively, yet undetected hybridization between the two species. The same may also hold true for frogs from Yapen that exhibit calls different from the sympatric P. papuensis. Tentatively referred to as Platymantis spec., these frogs are also genetically not well differentiated. It is furthermore concluded that the partly low genetic differentiation of the New Guinean Platymantis species render this group one of the cases in which DNA barcoding would likely fail to produce reliable results.     

Diagnostics of nocturnal calls of Sciaena umbra (L., fam. Sciaenidae) in a nearshore Mediterranean marine reserve

Calls emitted by the brown meagre Sciaena umbra (L., fam. Sciaenidae) were recorded at the Natural Marine Reserve of Miramare (Trieste, Italy) in seven nocturnal surveys (12-h continuous sampling) during the summer of 2009. Calls consist of pulses, with the main energy content below 2 kHz and mean peak frequency of c. 270 Hz. Pulses were short, with an average duration of 20 ms and a pulse period of 100 ms. Sounds lasted approximately 500 ms. Three types of sound patterns were recognized: irregular (I), regular (R) and the chorus (C). Their acoustic parameters are described showing that I, R and C differ in pulse duration, pulse peak frequency and pulse period. Occurrence of the three call types changes throughout the night: the R pattern occurred mainly at dawn and dusk, C predominated after nightfall, while I calls were produced sporadically during the whole nocturnal period. Our results indicate that S. umbra has a pronounced nocturnal rhythm in vocalizing behaviour and highlight how the diagnostic time–frequency pattern of S. umbra calls can be used to identify the species in the field. Considering that the abundance of S. umbra is currently declining, the information presented here will be relevant in developing non-invasive and low-cost monitoring acoustic systems for managing S. umbra conservation and fishery along the Mediterranean Sea.     

Vocal Responsiveness to Interfering Sounds By a Frog From The Southern Temperate Forest,Batrachyla leptopus

Interfering sounds from biotic and abiotic origins are likely to shape the responsiveness of sound communicating animals. Among these sources of interference, interactions among acoustically active species have been studied to quite a limited extent. The vocal responses of 20 male frogs Batrachyla leptopus from the temperate austral forest in Chile were tested with conspecific calls and with the calls of two sympatric species: Batrachyla taeniata and Batrachyla antartandica, broadcast at amplitudes of 73, 79, 85, 91 and 97 dB SPL peak. Also, the vocal activity of the subjects during exposure to a 3‐min continuous broadband noise presented at 67 dB SPL RMS was monitored. The subjects gave higher responses on average to the conspecific relative to the heterospecific calls, but in most comparisons, these differences did not reach levels of significance. In addition, the vocal activity of males of B. leptopus did not increase in the presence of the continuous broadband noise. The lack of clear preferential responses for conspecific signals contrasts with the sharp selectivities that B. taeniata and B. antartandica have shown for their own calls in previous studies. Such different vocal behavior could be related to the extensive geographic overlap of B. leptopus with the two other species in the temperate austral forest, where mixed choruses of this species with each of the two congeneric taxa have been reported to occur occasionally. The lack of vocal activation in the presence of continuous noise also contrasts with the increased vocal output with which the other two taxa respond to this intrusion and is likely to result from a relatively high spontaneous vocal activity in B. leptopus.     

Sound production by the Shi drum Umbrina cirrosa and comparison with the brown meagre Sciaena umbra: a passive acoustic monitoring perspective

Sounds produced by the Shi drum Umbrina cirrosa were short trains of pulses with an average pulse period of 180 ms, pulse duration of c. 40 ms and an average peak frequency of 400 Hz; average values of acoustical properties differed from those recorded from the brown meagre Sciaena umbra in previous studies. The present study provides a preliminary tool for discriminating between these two species while conducting passive acoustic monitoring. The potential effects of ontogeny on sound production in both species are discussed and recommendations are made for further research.