Mating Calls Research Articles

Sexual differences in prevalence of a new species of trypanosome infecting túngara frogs.

Trypanosomes are a diverse group of protozoan parasites of vertebrates transmitted by a variety of hematophagous invertebrate vectors. Anuran trypanosomes and their vectors have received relatively little attention even though these parasites have been reported from frog and toad species worldwide. Blood samples collected from túngara frogs (Engystomops pustulosus), a Neotropical anuran species heavily preyed upon by eavesdropping frog-biting midges (Corethrella spp.), were examined for trypanosomes. Our results revealed sexual differences in trypanosome prevalence with female frogs being rarely infected (<1%). This finding suggests this protozoan parasite may be transmitted by frog-biting midges that find their host using the mating calls produced by male frogs. Following previous anuran trypanosome studies, we examined 18S ribosomal RNA gene to characterize and establish the phylogenetic relationship of the trypanosome species found in túngara frogs. A new species of giant trypanosome, Trypanosoma tungarae n. sp., is described in this study. Overall the morphometric data revealed that the trypomastigotes of T. tungarae n. sp. are similar to other giant trypanosomes such as Trypanosoma rotatorium and Trypanosoma ranarum. Despite its slender and long cell shape, however, 18S rRNA gene sequences revealed that T. tungarae n. sp. is sister to the rounded-bodied giant trypanosome, Trypanosoma chattoni. Therefore, morphological convergence explains similar morphology among members of two non-closely related groups of trypanosomes infecting frogs. The results from this study underscore the value of coupling morphological identification with molecular characterization of anuran trypanosomes.

Acoustic Preference of Frog‐Biting Midges (Corethrella spp) Attacking Túngara Frogs in their Natural Habitat

AbstractIn many animals, males aggregate to produce mating signals that attract conspecific females. These leks, however, also attract eavesdropping predators and parasites lured by the mating signal. This study investigates the acoustic preferences of eavesdroppers attracted to natural choruses in a Neotropical frog, the túngara frog (Engystomops pustulosus). In particular, we examined the responses of frog‐biting midges to natural variation in call properties and signaling rates of males in the chorus. These midges use the mating calls of the frogs to localize them and obtain a blood meal. Although it is known that the midges prefer complex over simple túngara frog calls, it is unclear how these eavesdroppers respond to natural call variation when confronted with multiple males in a chorus. We investigated the acoustic preference of the midges using calling frogs in their natural environment and thus accounted for natural variation in their call properties. We performed field recordings using a sound imaging system to quantify the temporal call properties of males in small choruses. During these recordings, we also collected frog‐biting midges attacking calling males. Our results revealed that, in a given chorus, male frogs calling at higher rates and with higher call complexity attracted a larger number of frog‐biting midges. Call rate was particularly important at increasing the number of midges attracted when males produced calls of lower complexity. Similarly, call complexity increased attractiveness to the midges especially when males produced calls at a low repetition rate. Given that female túngara frogs prefer calls produced at higher repetition rates and higher complexity, this study highlights the challenge faced by signalers when increasing attractiveness of the signal to their intended receivers.

Eavesdropping to Find Mates: The Function of Male Hearing for a Cicada-Hunting Parasitoid Fly, Emblemasoma erro (Diptera: Sarcophagidae).

Females of several species of dipteran parasitoids use long-range hearing to locate hosts for their offspring by eavesdropping on the acoustic mating calls of other insects. Males of these acoustic eavesdropping parasitoids also have physiologically functional ears, but so far, no adaptive function for male hearing has been discovered. I investigated the function of male hearing for the sarcophagid fly Emblemasoma erro Aldrich, an acoustic parasitoid of cicadas, by testing the hypothesis that both male and female E. erro use hearing to locate potential mates. I found that both male and nongravid female E. erro perform phonotaxis to the sounds of calling cicadas, that male flies engage in short-range, mate-finding behavior once they arrive at a sound source, and that encounters between females and males at a sound source can lead to copulation. Thus, cicada calling songs appear to serve as a mate-finding cue for both sexes of E. erro. Emblemasoma erro’s mate-finding behavior is compared to that of other sarcophagid flies, other acoustic parasitoids, and nonacoustic eavesdropping parasitoids.

Silent listeners: can preferences of eavesdropping midges predict their hosts’ parasitism risk?

Eavesdropping predators and parasites that exploit the mating signals of their prey often prefer to approach certain signal variants. However, victim finding depends on many different factors. Therefore, preferences of eavesdroppers may not always directly reflect the predation or parasitism risk of the signaler. Frog-biting midges (Corethrella spp.) and their anuran hosts offer an excellent model system to investigate this correlation. Female Corethrella are vectors of trypanosomes in frogs and use the mating calls of their anuran hosts to localize them. We tested whether the acoustic preferences of Corethrella reflects the parasitism risk of male frogs by Corethrella and trypanosomes in the field. We conducted acoustic attraction and preference tests with Corethrella in the field and used the results of the preference tests to estimate a linear model (LM) and predict the parasitism risk of sympatric frog species by Corethrella. Our preference tests in the field showed that frog-biting midges preferred higher call rates, longer calls, a frequency around 2kHz, and sounds that were broadcast near the ground. Anuran species that were predicted by our LM to produce the most attractive signal showed the highest rates of parasitism by frog-biting midges and trypanosomes. Thus, acoustic preferences of eavesdropping Corethrella can be used to predict not only the parasitism rate of their host species by Corethrella but also the risk of subsequent trypanosome transmission.

Territorial calls analysis in the broad tailed bat (Nyctinomops laticaudatus)

Some bat families perform vocalizations called “songs” to mate, conformed by three element types: chirps, trills, and buzzes. Also, those might be territorial warning calls; but its syntax remains to be understood. Our goal is to get information about mating calls’ patterns and its clarified function for a molossid bat species. We used ultrasound microphones to record vocalizations from a colony of Nyctinomops laticaudatus, during three periods through 2013–2014. We performed spectrogram analysis to characterize vocalizations with chirp number, duration, and acoustic frequency measurements. Results show males perform structured and complex songs. Vocal repertoire features two chirp types, trills, and buzzes as in other species. Chirp A is a short descendant frequency modulated pulse of 8.05 ms (SD = 3.53 ms); chirp B is a downward FM larger than A with an upward final segment of 43.93 ms total length (SD = 14.85 ms). Distinctively Nyctinomops laticaudatus performs songs of a series of three to nine compou...

Reproduction and immunity trade-offs constrain mating signals and nuptial gift size in a bushcricket

Reproduction and immunity often require significant energetic investment and as a result, trade-offs may occur between them. Reproduction is particularly costly for males of the bushcricket Ephippiger diurnus: not only do they produce loud advertisement calls for long periods of time to attract mates but also they offer females a large nuptial gift, a spermatophore, that can be up to 40% of their body weight. Song traits and spermatophore size vary among males, implying that males may differ in their overall reproductive effort or in how their effort is allocated. Males are long-lived, suggesting that survival traits such as immunity may be particularly critical in fitness. Here, we tested the hypothesis that trade-offs exist between reproductive effort and immune response in E. diurnus and that such trade-offs may constrain male mating calls and nuptial gift size. We investigated the relationship between call syllable number, spermatophore size, and immune response in field-collected individuals. We found an inverse relationship in all pairwise comparisons of call syllable number, spermatophore size, and immune response, as well as between overall reproductive effort and immune response. Our results suggest that males exhibit different energy allocation strategies and that their trade-offs ultimately constrain signal evolution.

The largest relative testis size among primates and aseasonal reproduction in a nocturnal lemur, Mirza zaza.

Testis size is an indirect indicator of a species' mating system, along with sexual size and canine dimorphism, existence and usage of mating and advertisement calls as well as the spatial distribution of males and females ready to mate in solitary species. Upon its recent discovery, the northern giant mouse lemur Mirza zaza was suggested to have a polygynandrous mating system and to exhibit seasonal breeding. We tested these predictions in a field study in Sahamalaza National Park, NW Madagascar. We caught 12 M. zaza, before and during the suggested mating period and obtained standard field morphometric measurements, including testes size. We show that M. zaza has the highest relative testis volume among primates, indicating strong sperm competition and polygynandrous mating. In addition, based on inferred age of captured animals, observed mating behavior, a female caught in met-estrus and data from captivity, we suggest M. zaza to be one of the few lemurs that breed aseasonally. Future field work on this endangered species is required to illuminate the causes and consequences of intense promiscuity and aseasonal breeding despite strong habitat seasonality, which distinguish M. zaza from most other nocturnal lemurs.

Reinterpreting features of the advertisement call of Dermatonotus muelleri (Boettger, 1885; Anura, Microhylidae).

The advertisement call of Dermatonotus muelleri was originally described by Nelson (1973) in a brief section of a review on the mating calls of the Microhylinae. He used two calls from São Leopoldo, state of Minas Gerais, in Brazil to determine that they have i) dominant frequency between 1.500-2.200 kHz (mean 1.854 <span style="text-decoration: underline;">+ 0.216 kHz), and ii) harmonic intervals between 0.140 and 0.150 kHz (0.146 +/- 0.005 kHz). Nelson (1973) based his description on an audiospectrogram produced with high frequency resolution and did not quantify the pulse structure of the calls. More recently, Giaretta and colleagues (2013) expanded on the original description using a larger set of calls recorded from Gurinhat, state of Minas Gerais, in Brazil. They quantified the temporal structure of the call and confirmed that the dominant frequency is around 1.8 kHz. In addition, they identified a secondary low frequency band at 667 Hz.

Cues used in host-seeking behavior by frog-biting midges (Corethrella spp. Coquillet).

We investigated the role of carbon dioxide and host temperature in host attraction in frog-biting midges (Corethrella spp). In these midges, females are known to use frog calls to localize their host, but the role of other host-emitted cues has yet not been investigated. We hypothesized that carbon dioxide acts as a supplemental cue to frog calls. To test this hypothesis, we determined the responses of the midges to carbon dioxide, frog calls, and both cues. A significantly lower number of midges are attracted to carbon dioxide and silent traps than to traps broadcasting frog calls. Adding carbon dioxide to the calls does not increase the attractiveness to the midges. Instead, carbon dioxide can have deterrent effects on frog-biting midges. Temperature of calling frogs is not a cue potentially available to the midges. Contrary to our hypothesis, there was no supplemental effect of carbon dioxide when presented in conjunction to calls. Midge host-seeking behavior strongly depends on the mating calls emitted by their anuran host. Overall, non-acoustic cues such as host body temperature and carbon dioxide are not important in long-distance host location by frog-biting midges.

Dispatches

Dispatches

Mole Cricket (Orthoptera: Gryllotalpidae) Mating Calls: Characteristics in Recently Expanded Geographic Areas

Abstract Mole crickets (Orthoptera: Gryllotalpidae) damage warm-season turfgrasses throughout the southeastern United States. The two most destructive species are the southern mole cricket, Scapteriscus borellii Giglio-Tos, and the tawny mole cricket, S. vicinus Scudder. Both species use mating calls to attract and locate potential mates. Male mating calls have often been used to distinguish among different species of crickets. Calling characteristics can vary within a species due to numerous factors, including climate. There has been no research conducted on the call characteristics of mole crickets as they have expanded their range of inhabitance to North Carolina. Male calls of southern and tawny mole crickets were recorded at night in 2009 and 2010. Analysis of the calls indicated that there was little change in the calling characteristics from previous research. This allows us to continue to expand our management plans for this pest and coordinate our efforts with other regions where mole crickets a...

Newtonian and weighted essentially non-oscillatory models to describe the generation and propagation of the Cicada mating calls

Experiments and analyses of Hughes et al., JASA, 2009 are the origins of this research where we study the in-air waveform generation and propagation of the acoustic signals generated by cicadas. The sound generation is studied in a Newtonian model and the sound propagation is analysis by a numerical solver for viscous Burgers’ equation. The time histories from the tymbal surface velocities recorded by a laser Doppler vibrometer to the microphones positioned near the cicadas provide the test data. The Newtonian model describes the sound production systems process to generate the mating call signal structure. The numerical solver employs weighted essentially non-oscillatory (WENO) reconstruction to approximate the first and second derivatives of the semi-discrete operator. The WENO is utilizes due to the non-smooth structure of the cicada propagating waveform. Principally, the cicada mating signal in question has sharp transitions, since spectral methods tend to produce spurious oscillations as a result of attempting to represent a discontinuous function by a Fourier basis expansion. Thus, these analytical models are computationally tested to determine if the results capture the sound production and the transmission of the cicada mating calls. To verify the models are meaningful, the simulations are verified with real experimental data.

Use of acoustic signals in mating in an eavesdropping frog-biting midge

The sensory systems of organisms are shaped by selective pressures imposed by their performance in a variety of contexts. Female frog-biting midges use the mating calls of anurans to locate their host to obtain a blood meal. Although the use of sound in foraging is well documented in this group, it is unknown whether sound is used in other contexts. To investigate the ability to use sound in nonforaging contexts, we experimentally tested the prediction that frog-biting midges (Corethrella appendiculata) use sound in mating. We recorded their wing beats while swarming, in controlled tethered conditions and during different- and same-sex pair interactions. Our results show sexual differences in the acoustic properties of flight tones, with male midges having higher frequency wing beats than females. Wing beats of free-flying individuals were significantly higher in frequency than those recorded from tethered individuals, cautioning the interpretation of recordings obtained following this widely used technique. In addition, interacting, tethered opposite-sex pairs altered their flight tones to match their upper harmonics, converging at the third and fourth harmonic frequencies of males and females, respectively. In male–male interactions, however, the frequency of their wing beats diverged. Therefore, flight tones in frog-biting midges may function as courtship signals attracting conspecific females and deterring rival males. We discuss the use of sound in multiple contexts in these midges and potential factors leading to their ability to eavesdrop on anurans.

Differences in the male mating calls of co-occurring epauletted fruit bat species (Chiroptera, Pteropodidae, Epomophorus wahlbergi and Epomophorus crypturus) in Kruger National Park, South Africa.

Almost nothing is known about the mating ecology and behavior of epauletted fruit bats (Epomophorus spp) of which eight species occur worldwide. Two species of epauletted fruits bats (Epomophorus wahlbergiandEpomophoruscrypturus)overlap in their distributional ranges in Kruger National Park (KNP), South Africa. Morphologically, these two species are nearly identical to the human eye and field recognition is based upon the number and position of palatal rugae of captured individuals. In addition, the males of both species perform mating rituals during overlapping breeding seasons that appear quite similar and involve wing flapping and monotone vocalizations from calling stations in proximity to fruiting sycamore fig trees where females congregate to feed. The overlap in breeding seasons as well as physical and behavioral characteristics between these two species brings into question how species recognition occurs, and no research is available to understand how males are identified by the females of each species for mating purposes. We recorded vocalizations from calling males in local areas of KNP known to support both species and compared the sonograms to determine if the call structure of mating vocalizations between males of each species differs. Werecorded 25 mating vocalizations from seven male epauletted fruit bats near the Shingwedzi Research Camp and 31 mating vocalizations from nine individuals along the Sabie River near Skukuza. Analysis of calls showed significant distinctiveness of male mating vocalizations between the two species in terms of mean fundamental frequency, mean high frequency, mean low frequency, mean bandwidth, and mean call slope at the two sites. Wehypothesize that differences in male mating vocalizations recorded at each of our study sites represent call structure differences that potentially may be used to avoid cross-mating between species.

Traffic noise affects colouration but not calls in the European treefrog (Hyla arborea)

In terrestrial habitats, traffic noise is responsible for chronic noise exposure and impacts both signal detection and acoustic signal structure. Several species are known to adapt their call structures to cope with noise. However, compromised hearing affects more than acoustic communication, and noise should be consider as a stress factor that can also alter visual communication in the case of carotenoid-based signals. Here, we experimentally investigated the impact of traffic noise on the expression of secondary sexual signals in the European treefrog, Hyla arborea. Treefrogs use multimodal communication in the sexual selection process (mating calls and vocal sac colouration). We found that treefrogs seem unable to adjust their call structure. Nonetheless, males showed a significant decrease in colouration intensity. Our findings highlight for the first time the negative effect of traffic noise on colour signals. This suggests that anthropogenic noise could affect a wider range of species than previously thought.

Aposematism increases acoustic diversification and speciation in poison frogs.

Multimodal signals facilitate communication with conspecifics during courtship, but they can also alert eavesdropper predators. Hence, signallers face two pressures: enticing partners to mate and avoiding detection by enemies. Undefended organisms with limited escape abilities are expected to minimize predator recognition over mate attraction by limiting or modifying their signalling. Alternatively, organisms with anti-predator mechanisms such as aposematism (i.e. unprofitability signalled by warning cues) might elaborate mating signals as a consequence of reduced predation. We hypothesize that calls diversified in association with aposematism. To test this, we assembled a large acoustic signal database for a diurnal lineage of aposematic and cryptic/non-defended taxa, the poison frogs. First, we showed that aposematic and non-aposematic species share similar extinction rates, and aposematic lineages diversify more and rarely revert to the non-aposematic phenotype. We then characterized mating calls based on morphological (spectral), behavioural/physiological (temporal) and environmental traits. Of these, only spectral and temporal features were associated with aposematism. We propose that with the evolution of anti-predator defences, reduced predation facilitated the diversification of vocal signals, which then became elaborated or showy via sexual selection.

Automatic recognition of anuran species based on syllable identification

Monitoring of biological populations is well known for being a complex task that involves high operational costs, unknown reproductive intervals of the studied species, and difficult visualization of isolated individuals (due to their mimetic and cryptic capabilities). Therefore, the development of new methodologies able to measure quantities of individuals in specific biological populations without direct contact is desired. Species and individual recognition, based on acoustic analysis of their calls (Bioacoustics), is possible for many animals and has proven to be a useful tool in the study and monitoring of animal species. In this paper, an unsupervised methodology for anuran automatic identification is proposed; it is based on the use of a fuzzy classifier and Mel Frequency Cepstral Coefficients. This methodology is able to detect species not presented in the training stage, although they belong to different populations. Additionally, correlations among species of the same genus can be determined through the similarities of their calls. For testing the proposed method, two different datasets with species from the northeastern Colombia (Chocó and Antioquia departments with 103 and 813 mating calls respectively) were used. In validation tests performed, accuracies between 99.38% and 100% were achieved in all species by applying the proposed methodology to both datasets. Thirteen different species of anurans in both datasets were correctly identified.

Why should a U.S. Navy researcher discuss cicada mating calls for hours with several journalist?

The first journalist to comment officially on my cicada research was by American Institute of Physics (AIP), which was quickly followed up by a LA Times reporter. Unfortunately, the LA Times author wrote how the cicada sound system functioned like a Helmholtz resonator. However, when the author actually interviewed me, I contradicted the journalist by saying that I do not believe that theory was correct. Furthermore, I was interviewed by a radio commentator for National Public Radio (NPR) as well who diligently discussed my research and its inspiration for 50 min. My segment aired for 2 min and those few seconds consisted of “crude construction worker harassment and bar talk.” Overall, the opportunity of communicating my research to an international audience was outstanding. The other correspondents that interviewed me for the article were from the ScienceNow and Wall Street Journal. Also, one of my interviewers was a writer for Le Presse so the immediate columnist coverage did span at least two countries. I am proud to have bought awareness to an insect that has been on earth with civilized mankind for millennia; nonetheless, our practical knowledge of the cicada is rather limited.

No preference in female sika deer for conspecific over heterospecific male sexual calls in a mate choice context

AbstractMating signals can be used both in contexts of species recognition and mate quality assessment. This study examines species recognition abilities in oestrous females presented with male mating calls from both conspecifics and closely related allopatric heterospecifics. Red deer and sika deer are naturally allopatric polygynous species capable of hybridization during sympatry. Male mating calls are sexually selected and differ greatly between species. Previous work indicated that most but not all oestrous red deer hinds prefer male mating calls from conspecifics over heterospecific sika deer. Using two‐speaker playback experiments, we extend this examination by measuring the preference responses of oestrous sika deer hinds to these stimuli. We predicted that oestrous sika deer hinds will show little flexibility in behavioural responses and prefer conspecific calls over heterospecific calls, similar to those of red deer hinds. In contrast, sika deer hinds showed high levels of flexibility and no difference in overall preference behaviours, suggesting that vocal behaviour does not provide a solid barrier to hybridization in this species. The asymmetry in heterospecific preference responses between these species is discussed in relation to possible causation and hybridization patterns observed in free‐ranging populations.

Discovery of organ explains koalas' super-bass notes

Throat structure explains why male mating calls are bizarrely deeper than expected for the animal's size.