Vocalisation and its association with androgens and corticosterone in a night frog (Nyctibatrachus humayuni) with unique breeding behaviour

In anurans, vocalisation is used to communicate within and between the sexes during reproduction. Knowledge of vocal repertoire and its diversity is essential in understanding its significance in sexual selection. In this context, we studied the vocal behaviour of Nyctibatrachus humayuni and quantified the urinary metabolites of androgens and corticosterone to understand the associations among hormones, body condition index and vocalisation. Our results show that males of N. humayuni produce an amplitude‐modulated call consisting of a train of pulses. Interestingly, a high degree of inter‐individual variation was observed in the call parameters. The dominant frequency and pulse interval were negatively correlated with male body size, whereas pulse duration and pulse duty cycle were positively correlated with it. Dominant frequency was negatively correlated with androgens and corticosterone, whereas pulse interval was negatively correlated with corticosterone. Further, pulse duty cycle, pulse duration and pulses per call were positively associated with corticosterone. Surprisingly, none of the acoustic parameters was associated with male body temperature and body condition. A significant variation was evident in the vocal effort, dominant frequency and amplitude of advertisement calls produced under different social situations. Calls produced during territory establishment had lower dominant frequency but higher vocal effort, whereas those produced during courtship had higher amplitude and vocal effort than the calls produced in the absence of a competitor/female. Our results suggest that greater inter‐male variability in the advertisement call of N. humayuni could be important in female choice as it may help females to assess the quality of a male. Further, androgens and corticosterone could be important in modulating crucial parameters of the advertisement call.     

Calls of the black drum (Pogonias cromis: Sciaenidae): geographical differences in sound production between northern and southern hemisphere populations

Because of apparent reproductive isolation between Northern and Southern hemisphere populations of the black drum Pogonius cromis, we tested the hypothesis that advertisement calls from a southern population would differ from known calls of North American populations. Additionally, we quantified disturbance and advertisement calls, their changes with fish size and sex, not previously examined in this species. Unlike most sciaenids, both sexes of P. cromis possess robust sonic muscles, and both produce disturbance calls when handled. However, only males produce an advertisement call used in courtship. The disturbance call consists of a variable train of short-duration pulses (average 23?ms). The duration, interpulse interval, and dominant frequency of pulses are similar in males and females and change developmentally: pulse duration and interpulse interval increase and dominant frequency decreases with fish size. Advertisement calls, recorded in the field and in captivity, are long-duration (average 184?ms) and tonal. Based on variation in fundamental frequency, which decreases with fish size, field choruses are composed of different-sized individuals. The duration of advertisement calls, about a third of those from Florida populations, suggests genetic differentiation between northern and southern populations.     

Morphometric and advertisement call geographic variation in polyploid green toads

We describe the spatial pattern of variation of morphometric characters and call acoustic properties of tetraploid green toads [Bufo viridis complex) from eight populations in Central Asia, and we analyse the causal agents responsible for the patterns observed, by means of partial Mantel tests. Populations significantly differ with respect to both body size and body shape. Since animals inhabiting the driest regions are smaller, but not younger, man animals from less dry areas, we suggest that their small body size is due to the limiting effect of arid climate on growth rate. Differences in body shape are positively associated only with geographic distances, and we suggest that isolation by distance might have played an important role in determining the pattern of variation. Populations significantly differ also with respect to the acoustic properties of the call, in particular, with respect to temperature-adjusted pulse rate and body size-adjusted fundamental frequency; that is, with respect to those properties which are under the strongest morphological or physiological constraints, and that show the lowest variability within individuals (static properties). The pattern of variation of calls shows positive association with geographic distances, but not with climatic distances. Calls do vary, and in this region the main causal agent responsible for call variation might have been the isolation by distance. The evolutionary implications of these results are discussed.     

Call Characteristics of Two Sympatric and Morphologically Similar Tree Frogs Species,Polypedates megacephalus and Polypedates mutus(Anura: Rhacophoridae), from Hainan,China

Anuran calls are usually species-specific and therefore valued as a tool for species identification. Call characteristics are a potential honest signal in sexual selection because they often reflect male body size. Polypedates megacephalus and P. mutus are two sympatric and morphologically similar tree frogs, but it remains unknown whether their calls are associated with body size. In this study, we compared call characteristics of these two species and investigated any potential relationships with body size. We found that P. megacephalus, males produced six call types which consisting of three distinct notes, while P. mutus males produced five types consisting of two types of notes. Dominant frequency, note duration, pulse duration, and call duration exhibited significant interspecific differences. In P. megacephalus, one note exhibited a dominant frequency that was negatively correlated with body mass, snout-vent length, head length, and head width. In P. mutus, the duration of one note type was positively correlated with body mass and head width. These differences in call characteristics may play an important role in interspecific recognition. Additionally, because interspecific acoustic variation reflects body size, calls may be relevant for sexual selection. Taken together, our results confirmed that calls are a valid tool for distinguishing between the two tree-frog species in the field.     

Female Preferences for Call Traits and Male Mating Success in the Neotropical Frog Physalaemus enesefae

Female preferences for male call traits may affect male mating success and the evolution of exaggerated secondary sexual traits. We used phonotaxis experiments to examine female preferences in the frog Physalaemus enesefae in relation to variation in male call duration, dominant frequency, intercall interval and amplitude (dB SPL). Females preferred long calls, low and average dominant frequency calls, short intercall intervals and more intense calls. We compared the patterns of female preferences with those of acoustic variation among males to test the prediction that properties with low within‐male variation are associated with stabilizing or weakly directional female preferences, whereas properties with high within‐male variation are associated with directional preferences. Females had weakly directional preferences for the dominant frequency of the call and strongly directional preferences for call duration and call rate. We also determined whether the temporal relationship between calls influenced preferences based on the dominant frequency of the call. Preferences for low‐frequency over high‐frequency calls disappeared when calls partially overlapped. Females preferred the leading call regardless of its dominant frequency. We also investigated mating patterns in the field. There was size‐assortative mating, as male and female body sizes snout‐vent length (SVL) were positively correlated. In addition, differences in the frequency distributions of body length (SVL) between mated and unmated males approached significance; lower SVL classes were underrepresented among mated males. These patterns may reflect female preferences for lower dominant frequency calls, as there is a negative correlation between male mass and the dominant frequency of the call.     

Preferences for Call Spectral Properties in Hyla intermedia

We studied the pattern of variation in the spectral properties of male advertisement calls and female preference functions for these same properties in the Italian treefrog (Hyla intermedia). The call spectral properties (fundamental and dominant frequencies) were highly negatively correlated with body size, they showed low within‐individual variation, and, at the population level, they were found to be under weak stabilizing selection. In two‐choice discrimination tests, females did not show preferences between calls with fundamental and dominant frequencies within two standard deviations from the population mean, whereas females significantly discriminated against calls when their frequencies were three (or more) standard deviations above or below the population mean. Consistent with the observed permissiveness in female preference over the call spectral structure, in the natural population, we found no evidence either of directional selection on male body size or of a size‐assortative mating pattern. The pattern of preferences observed at the population level did not mirror the preferences of individual females. In fact, in a multi‐trial discrimination experiment, females showed significant differences in their choice between the average frequency call and a two standard deviation lower than average frequency alternative, for which no significant preferences were observed at the population level. Variations in preference were not found to correlate with female body size.     

Sound production in the whitemouth croaker and relationship between fish size and disturbance call characteristics

The whitemouth croaker produces two different sounds using extrinsic sonic muscles: (1) male advertisement calls during the spawning season and (2) disturbance calls, produced by both sexes. The advertisement call, related to courtship, was recorded in the field and from two marked spawning males of 28 and 30.5 cm L_T in the laboratory. It consists of individual pulses with average durations of 19.7 ms and 17.8 ms for the two males respectively, interpulse intervals of 496 ms and 718 ms, and dominant frequencies of 280 Hz and 316 Hz. Pulses are emitted in bouts of one to three min duration. Disturbance calls consist of a burst of pulses produced at short intervals, and the pulse duration, interpulse interval and dominant frequency of the pulses average 19.8 ms, 17.1 ms, and 363 Hz, respectively. Dominant frequency and interpulse interval decrease and pulse duration increases with fish size. Sound characteristics change markedly in young of the year individuals (lower than 25 cm L_T) after which they appear to stabilize. Higher dominant frequency in the advertisement than in the disturbance call and the relationship of dominant frequency to pulse duration suggest that dominant frequency is determined as a forced response to muscle contraction parameters rather than by the natural frequency of the swimbladder.     

Variation in Male Calling Behaviour and Relation to Male Mating Success in the Strawberry Poison Frog (Dendrobates pumilio)

Calling behaviour and the characteristics of the males’ call are important for mate attraction, female mate choice and male mating success in anurans. In this study I investigated the variation in calling activity and the variation in one spectral (dominant frequency) and four temporal properties (call rate, call duration, duty cycle and pulse rate) of the advertisement call of strawberry poison frogs, Dendrobates pumilio, in two Costa Rican populations during two study periods. Regarding all call properties, no differences were found between populations or years, but between‐male variation was significantly higher than within‐recording and within‐male variation. Dominant frequency was less variable within and among males than temporal call properties and I classified the former as static and the latter as intermediate properties of the call. No call property seemed to be strongly affected by body length or weight. Moreover, I used behavioural observations to relate male calling behaviour to mating success. Calling activity was more variable between males and accounted for more variability in mating success in multiple regression models than any call property. Some call properties (call rate, dominant frequency and pulse rate) were also related to male mating success in one or two study periods. These call properties are probably important for females during courtship to assess their prospective mate and/or for competitive male–male interactions. Furthermore, I compared call properties and mating success of some males for which data were available for both study periods. Pulse rate was lower in the second than in the first year, suggesting age‐related changes in this call property. Moreover, male D. pumilio increased their relative mating success from the first to the second study year. Together with other studies, the data of this study suggest that, in anurans, endurance rivalry contributes more to variation in male mating success than does female choice based on male characteristics.     

饰纹姬蛙求偶鸣声特征分析

2012年5月,用SX950录音笔和Praat声音分析软件对浙江丽水繁殖季节饰纹姬蛙(Microhyla ornata)求偶鸣声进行录制和特征分析.结果表明,饰纹姬蛙发出的求偶鸣声具有单一谐波鸣声结构、多脉冲(7、9～16)及纺锤形振幅等特征;所有鸣声主频率范围为1.22～4.09 kHz (n=233),且由不同脉冲数组成的鸣声主频率平均值几近相等;叫声时程随脉冲数的增加而增大,脉冲时程在不同脉冲数鸣声中的大小几近相等,但最后一个脉冲的时程大小≤其他脉冲;脉冲间隔与叫声时程则刚好相反,即叫声时程越短,脉冲间隔就越大.在7个脉冲的鸣声中,其脉冲间隔最大,脉冲率最小;而在16个脉冲的鸣声中,脉冲间隔则最小,脉冲率最大.除7个脉冲和16个脉冲鸣声的脉冲率分别与其他鸣声存在显著性差异以外,随着叫声时程和脉冲数的增加,脉冲率也出现相应变化.在声强方面,除16个脉冲鸣声与其余所有的脉冲鸣声出现显著性差异以外,其他脉冲鸣声之间的两两比较差异不显著.丽水种群与其他5个地理种群(杭州、宣城、Kamoor、Bajipe和Padil)的鸣声特征比较显示饰纹姬蛙在不同地理种群的鸣声结构相似,而鸣声主频率、叫声时程、脉冲时程及脉冲率等在6个地理种群种均出现不同程度的差异.了解不同物种的声信号特征有助于更好地理解动物通讯行为及其进化特点.     

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.     

皮氏菊头蝠回声定位声波与年龄的关系

皮氏菊头蝠 (Rhinolophuspearsoni)雌性成体 5只和幼体 2只采自贵州省贞丰县珉谷镇。采用超声波探测仪 (D980 ,ULTRASOUNDDETECTOR)接收皮氏菊头蝠的回声定位声波 ,转换到原频率的 1 / 1 0后导入计算机 ,然后用专业声谱分析软件 (Batsound 3 1 0 )进行分析。成蝠在飞行和悬挂状态下的声波结构相似 ,只是声波各项参数值略有不同 :它们发射FM CF FM型声波 ,具有 2～ 3个谐波 ,主频率在飞行时为 5 6 80± 0 6 2kHz ,悬挂时为 5 8 0 5± 0 2 4kHz ;声脉冲时间和间隔在飞行时分别为 3 4 6 2± 5 2 9ms和 86 5 0± 1 9 72ms ,悬挂时分别为 4 1 0 8± 5 87ms和 1 1 7 2 9± 6 6 4 4ms ;能率环飞行时为 ( 4 4 0 6± 1 2 5 8) % ,悬挂时为 ( 4 6 0 0±2 4 2 5 ) %。幼蝠声波为CF FM型 ,谐波数为 5～ 8个 ,主频率明显低于成体 ,FM带宽窄于成体 ,声脉冲时间和间隔短于成体 ,能率环低于成体。皮氏菊头蝠回声定位声波与年龄有关 ,这可能因成体的声波主要是探测食物和周围环境的详细信息 ,而幼体主要是与母蝠进行交流。     

The water frogs of Greece: Bioacoustic evidence for a new species

The structure of the mating call of lake frogs (referred to as R. ridibunda) from 16 populations in Greece was analyzed for local variation using multivariate statistics. The populations of Thrace and of the island of Samothraki form a group giving the same type of mating call, whereas the mating call of the other populations differs in the degree of temperature dependence of four parameters, and specifically in the number of pulses/pulse group and pulse groups/call. Discriminant functions distinguish even single call series with a probability of 97%, intermediate mating calls are absent, and there is a significant, but slight differentiation of external morphological characters. These results have strong taxonomic implications. We conclude that the lake frogs of Greece comprise two species. The mating call of the lake frogs from Thrace resembles in all parameters that of the Rana ridibunda in the terra typica restricta (Guryev, CIS). Accordingly, the lake frogs of eastern Greece belong to R. ridibunda. The mating call of these lake frogs consists of 20 pulses/pulse group and of 7 pulse groups/call on the average. Most of Greece is inhabited by the second taxon, Rana balcanica sp. n. Its mating call is characterized by 27 pulses/pulse group and 4 pulse groups/call on the average. The two species in Greece do not differ with respect to coloration and size, but several standardized indices vary significantly: body length/digitus primus length; body length/callus internus length; body length/snout-eye distance; body length/tympanum diameter; tibia length/callus internus length; maximal head width/snout-eye distance.     

Stress hormone is implicated in satellite-caller associations and sexual selection in the Great Plains toad

The effects of androgens on male-typical traits suggest that variation among males in circulating levels can play a major role in sexual selection. We examined whether variation in vocal attractiveness is attributable to differences in androgen levels among Great Plains toads (Bufo cognatus). We found that noncalling "satellite" males practicing an alternative mating tactic were more likely to associate with males producing long calls. However, callers with satellites did not have higher androgen levels than callers without satellites. Rather, callers with satellites had significantly lower corticosterone (CORT) levels than callers without satellites. A CORT manipulation experiment suggested that differences in calls for males with and without satellites were related to differences in CORT levels. Furthermore, there was a negative correlation between CORT level and call duration within most nights of chorus activity. However, the correlation was weak for the pooled data (across all nights), suggesting that local environmental and/or social factors also affect call duration. Last, we show that females preferred broadcast calls of longer duration, characteristic of males with satellites and low CORT. These results imply that satellites optimize their reproductive success by associating with males producing long calls. However, this association should negatively affect the fitness of attractive callers.     

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.     

A comparative study of auditory sensitivity in the genus Bufo (amphibia)

Multi-unit response from the torus semicircularis were recorded to obtain neural audiograms for five different species, subspecies and races of the genus Bufo:Bufo b.bufo, Bufo b. spinosus, two races of Bufo viridis, and Bufo americanus.All of the audiograms were clearly bimodal, with a low frequency peak and a high frequency peak. A less pronounced but distinguishable intermediate peak seems to be an indication of trimodality. In the low-frequency range, the audiograms of the five groups differed little or not at all. There were pronounced differences, however, in the high-frequency range. This frequency band includes the frequencies of the conspecific mating calls. The best matching between call frequency and auditory best frequency was found in the Bufo viridis group.While it is likely that factors other than the signal characteristics in the vocal repertoire may shape the sensitivity of the auditory system, it is notable that those anuran species in which the mating call clearly facilitates reproduction have a more pronounced sensitivity peak at the frequencies in their mating calls.     

The genetic basis and evolution of acoustic mate recognition signals in a Ribautodelphax planthopper (Homoptera,Delphacidae) 1. The female call

Both sexes of the planthopper Ribautodelphax imitans produce species specific acoustic signals. Earlier experiments have shown that isolation between Ribautodelphax species in captivity is at least partly due to male preference for calls of conspecific females. The genetic basis of the female call is studied by bi-directional artificial selection for large and small interpulse intervals (IPI). This resulted in non-overlapping distributions of IPI after only five generations. The mean of eight realized heritability estimates over five generations was above 80%; estimates over ten generations were generally well above 50%. The character is shown to be of a polygenic nature, determined by at least 6 segregating genetic factors. The other features of the female call, strophe duration, and modulation of pulse repetition frequency within the strophe, showed significantly correlated responses. Sexual isolation tests after 10 generations of selection revealed significant symmetrical assortative mating, but coselected males did not exhibit a significant preference for playback calls of females from their own selection line. In view of the high heritability for the call character, and the considerable ecological isolation among Ribautodelphax species, it seems unlikely that the female call differentiated as an adaptation to prevent hybridization (reinforcement). More likely, call and call preference were shaped by sexual selection during allopatry, and may have (had) incidentally an effect in species isolation.     

Call Intensity and Female Preferences in the European Green Toad

In the present paper we study the pattern of variation in call intensity in a natural population of the European green toad (Bufo viridis), and we analyse females preferences for this property by means of playback experiments. Although call sound pressure level (SPL) shows little within‐bout variation, we found significant positive correlation between call SPL and fundamental frequency: on average, an increase of 6 dB SPL produces a 100‐Hz increase in fundamental frequency. When females were given a choice between two calls differing by 10 and 6 dB SPL, they significantly preferred the loudest call, whereas they did not discriminate between calls differing by 3 dB. To test whether a 3‐dB difference reflects a sensory or behavioural limit, we carried out three experiments where females were given a choice between two calls differing in both duration (4 s and 6 s, respectively) and SPL (3 dB). In all three experiments, the longer call attracted a larger number of females, but the 3‐dB difference did not show any significant effect. Finally, we investigated the relationships between call intensity and frequency on female preferences. Previous experiments showed size‐dependent preferences for calls with lower‐than‐average frequencies (1.3 kHz) over calls with higher‐than‐average frequencies (1.6 kHz). Here, we show that this weak preference is abruptly reversed when the highest‐pitched call is broadcast at an intensity 6 dB higher than the alternative.     

普氏蹄蝠(Hipposideros pratti)回声定位声波、形态及捕食策略

研究了普氏蹄蝠（Hipposideros pratti)不同状态（飞行,悬挂）下的回声定位声波特征,形态特征和生态特征（捕食策略,捕食地和食物类型）。结果表明,普氏蹄蝠的回声定位声波为CF－FM型,在不同状态下,主频率有一定的差异,飞行状态的主频率略低于悬挂状态,表明普氏蹄蝠是利用多谱勒补偿效应来适应飞行速度引起的主频率变化,以进行准确的定位和有效的捕食;同时飞行状态下声脉冲时间,声脉冲间隔时间及FM带宽略低于悬挂状态,而声脉冲重复率和能率环略主于悬挂状态,表明普氏蹄蝠在不同状态下利用不同特征的声波进行捕食,由回声定位声波推断和野外观察可知,普氏蹄蝠可能在树冠周围以盘旋方式（在昆虫高峰期）或以捕蝇器式（在昆虫高峰期这后）捕食中等偏大的振翅昆虫（如甲虫）。     

Rapid diversification of male genitalia and mating strategies in Ohomopterus ground beetles

We analysed evolutionary diversification and covariation in male genitalia and four mating traits related to sexual selection, i.e. testis size, spermatophore size, copulation duration and post-copulatory guarding duration, in Ohomopterus ground beetles using phylogenetically independent contrasts. Male genital size and mating duration have evolved more rapidly than body size and the other traits studied. Male genital size was negatively correlated with copulation duration, suggesting that elongated male genitalia may enable decreased time investment in a single copulation because it is more effective at facilitating spermatophore deposition. Male genital size was positively correlated with spermatophore size, suggesting coevolution between offensive and defensive male mating tactics because the elongated male genitalia may be advantageous in displacement of rivals' plug-like spermatophores, and decreased mating duration may intensify sperm competition. Thus, the remarkable diversity of male genitalia in Ohomopterus may have been facilitated by the interplay between inter- and intrasexual selection processes.     

The sexual arms race and phenotypic correlates of mating success in the waterstrider,Aquarius remigis (Hemiptera: Gerridae)

Intersexual conflicts over mating decisions may have an important impact on the evolution of mating behaviours and strategies and may develop into an arms race between the sexes. In waterstrider species, where intersexual conflict is known to occur, the evolution of male traits that allow them to overcome female reluctance to mate is expected. Reproductively active waterstriders,Aquarius remigis, were videotaped in the laboratory to examine the influence of total body length and front femoral width of males, male: female body size ratio, and female reproductive condition (number of mature eggs) on three variables associated with mating success: duration of the premating struggle, duration of mating, and number of successful matings. None of these behaviors was significantly correlated with the size ratio of the mating pair. However, total body length was negatively correlated with premating struggle duration, male front femoral width was positively correlated with number of successful matings, and number of mature eggs in females was positively correlated with duration of both the premating struggle and the mating itself. The relative influence of male sexual armaments and female choice on the outcome of mating interactions is discussed.