Mating call pattern of Green toads in Isreal and its ecological corelate

The mating calls of Bufo viridis populations from Israel were studied and compared with that of a Central-European population in order to evaluate their nature, variation and evolutionary origin. In Israeli Bufo viridis , call duration, pulse duration and interpulse interval are negatively correlated with temperature, whereas fundamental frequency is negatively correlated with body size. The Israeli and Central-European Bufo viridis are almost identical in call duration, pulse number, pulse duration and pulse rate. They differ slightly but significantly in interpulse interval and more obviously, in their fundamental frequency. The latter is correlated with body size. Since Israeli Bufo viridis are much larger than the Central-European ones, their fundamental frequency is distinctly lower.
Bufo viridis illustrates a case in which variation in the fundamental frequency of the mating call is probably largely an incidental product of adaptive differentiation of body size to the humidity index.     

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.     

Tight hormonal phenotypic integration ensures honesty of the electric signal of male and female Brachyhypopomus gauderio

Hormones mediate sexually selected traits including advertisement signals. Hormonal co-regulation links the signal to other hormonally-mediated traits such that the tighter the integration, the more reliable the signal is as a predictor of those other traits. Androgen administration increases the duration of the communication signal pulse in both sexes of the electric fish Brachyhypopomus gauderio. To determine whether the duration of the signal pulse could function as an honest indicator of androgen levels and other androgen-mediated traits, we measured the variation in sex steroids, signal pulse duration, and sexual development throughout the breeding season of B. gauderio in marshes in Uruguay. Although the sexes had different hormone titres and signal characteristics, in both sexes circulating levels of the androgens testosterone (T) and 11-ketotestosterone (11-KT) were strongly related to signal pulse duration. Consequently, signal pulse duration can serve as an honest indicator of circulating androgens in males and females alike. Additionally, through phenotypic integration, signal pulse duration also predicts other sexual traits directly related to androgen production: gonad size in males and estradiol (E2) levels in females. Our findings show that tight hormonal phenotypic integration between advertisement signal and other sex steroid-mediated traits renders the advertisement signal an honest indicator of a suite of reproductive traits.     

Electric organ morphology of Sternopygus macrurus, a wave-type, weakly electric fish with a sexually dimorphic EOD.

In several species of electric fish with a sex difference in their pulse-type electric organ discharge (EOD), the action potential-generating cells of the electric organ (electrocytes) of males are larger and more invaginated compared to females. Androgen treatment of females and juveniles produces a longer-duration EOD pulse that mimics the mature male EOD, with a concurrent increase in electrocyte size and/or membrane infolding. In Sternopygus macrurus, which generates a wave-type EOD, androgen also increases EOD pulse duration. To investigate possible morphological correlates of hormone-dependent changes in EOD in Sternopygus, we examined electric organs from both fish collected in the field, and untreated and androgen-treated specimens in the laboratory. The electrocytes are cigar shaped, with prominent papillae on the posterior, innervated end. Electrocytes of field-caught specimens were significantly larger in all parameters than were electrocytes of specimens maintained in the laboratory. EOD pulse duration and frequency were highly correlated, and were significantly different between the sexes in sexually mature fish. Nevertheless, no sex difference in electrocyte morphology was observed, nor did any parameters of electrocyte morphology correlate with EOD pulse duration or frequency. Further, whereas androgen treatment significantly lowered EOD frequency and broadened EOD pulse duration, there was no difference in electrocyte morphology between hormone-treated and control groups. Thus, in contrast to results from studies on both mormyrid and gymnotiform pulse fish, electrocyte morphology is not correlated with EOD waveform characteristics in the gymnotiform wave-type fish Sternopygus. The data, therefore, suggest that sex differences in EOD are dependent on changes in active electrical properties of electrocyte membranes.     

Electric organ morphology of Sternopygus macrurus,a wave-type,weakly electric fish with a sexually dimorphic EOD

In several species of electric fish with a sex difference in their pulse-type electric organ discharge (EOD), the action potential-generating cells of the electric organ (electrocytes) of males are larger and more invaginated compared to females. Androgen treatment of females and juveniles produces a longer-duration EOD pulse that mimics the mature male EOD, with a concurrent increase in electrocyte size and/or membrane infolding. In Sternopygus macrurus, which generates a wave-type EOD, androgen also increases EOD pulse duration. To investigate possible morphological correlates of hormone-dependent changes in EOD in Sternopygus, we examined electric organs from both fish collected in the field, and untreated and androgen-treated specimens in the laboratory. The electrocytes are cigar shaped, with prominent papillae on the posterior, innervated end. Electrocytes of field-caught specimens were significantly larger in all parameters than were electrocytes of specimens maintained in the laboratory. EOD pulse duration and frequency were highly correlated, and were significantly different between the sexes in sexually mature fish. Nevertheless, no sex difference in electrocyte morphology was observed, nor did any parameters of electrocyte morphology correlate with EOD pulse duration or frequency. Further, whereas androgen treatment significantly lowered EOD frequency and broadened EOD pulse duration, there was no difference in electrocyte morphology between hormone-treated and control groups. Thus, in contrast to results from studies on both mormyrid and gymnotiform pulse fish, electrocyte morphology is not correlated with EOD waveform characteristics in the gymnotiform wave-type fish Sternopygus. The data, therefore, suggest that sex differences in EOD are dependent on changes in active electrical properties of electrocyte membranes. © 1992 John Wiley & Sons, Inc.     

Temporal selectivity by single neurons in the torus semicircularis of Batrachyla antartandica (Amphibia: Leptodactylidae)

We investigated the response selectivities of single auditory neurons in the torus semicircularis of Batrachyla antartandica (a leptodactylid from southern Chile) to synthetic stimuli having diverse temporal structures. The advertisement call for this species is characterized by a long sequence of brief sound pulses having a dominant frequency of about 2000 Hz. We constructed five different series of synthetic stimuli in which the following acoustic parameters were systematically modified, one at a time: pulse rate, pulse duration, pulse rise time, pulse fall time, and train duration. The carrier frequency of these stimuli was fixed at the characteristic frequency of the units under study (n=44). Response patterns of TS units to these synthetic call variants revealed different degrees of selectivity for each of the temporal variables. A substantial number of neurons showed preference for pulse rates below 2 pulses s(-1), approximating the values found in natural advertisement calls. Tonic neurons generally showed preferences for long pulse durations, long rise and fall times, and long train durations. In contrast, phasic and phasic-burst neurons preferred stimuli with short duration, short rise and fall times and short train durations.     

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）。     

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.     

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CFFM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高于悬挂状态,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(在昆虫高峰期之后)捕食中等偏大的振翅昆虫(如甲虫).     

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.     

Precipitation pulses and carbon fluxes in semiarid and arid ecosystems

In the arid and semiarid regions of North America, discrete precipitation pulses are important triggers for biological activity. The timing and magnitude of these pulses may differentially affect the activity of plants and microbes, combining to influence the C balance of desert ecosystems. Here, we evaluate how a pulse of water influences physiological activity in plants, soils and ecosystems, and how characteristics, such as precipitation pulse size and frequency are important controllers of biological and physical processes in arid land ecosystems. We show that pulse size regulates C balance by determining the temporal duration of activity for different components of the biota. Microbial respiration responds to very small events, but the relationship between pulse size and duration of activity likely saturates at moderate event sizes. Photosynthetic activity of vascular plants generally increases following relatively larger pulses or a series of small pulses. In this case, the duration of physiological activity is an increasing function of pulse size up to events that are infrequent in these hydroclimatological regions. This differential responsiveness of photosynthesis and respiration results in arid ecosystems acting as immediate C sources to the atmosphere following rainfall, with subsequent periods of C accumulation should pulse size be sufficient to initiate vascular plant activity. Using the average pulse size distributions in the North American deserts, a simple modeling exercise shows that net ecosystem exchange of CO₂ is sensitive to changes in the event size distribution representative of wet and dry years. An important regulator of the pulse response is initial soil and canopy conditions and the physical structuring of bare soil and beneath canopy patches on the landscape. Initial condition influences responses to pulses of varying magnitude, while bare soil/beneath canopy patches interact to introduce nonlinearity in the relationship between pulse size and soil water response. Building on this conceptual framework and developing a greater understanding of the complexities of these eco-hydrologic systems may enhance our ability to describe the ecology of desert ecosystems and their sensitivity to global change.     

Variation in the Sonar of an Aerial-hawking Bat (Eptesicus nilssonii)

Echolocation calls from 10 individually marked female northern bats (Eptesicus nilssonii) were recorded as the bats foraged at three distinct feeding sites (territories) near their maternity roost in southern Sweden (57° N). In addition, recordings of unmarked bats were made in northern Sweden (65° N). The frequency at maximum amplitude of “search phase” echolocation pulses was bimodally distributed, with peaks around 29–30 kHz and 31–32 kHz and was negatively correlated with pulse duration. The frequency at maximum amplitude was related to flight altitude (bats used higher frequencies when they flew near the ground) and also differed among the feeding sites. Hence, much of the variation, probably including regional differences, was behavioural and is interpreted as short term (in the order of s or min) adaptation to current foraging situations. Variation among individual bats, caused by age and size, seemed to be of less importance. Individuals did not use exclusive frequency bands.     

Androgens alter electric organ discharge pulse duration despite stability in electric organ discharge frequency.

Weakly electric fish in the genus Sternopygus emit a sinusoidal, individually distinct, and sexually dimorphic electric organ discharge (EOD) that is used in electrolocation and communication. Systemically applied androgens decrease EOD frequency, which is set by a medullary pacemaker nucleus, and increase pulse duration, which is determined by the cells of the electric organ (the electrocytes), in a coordinated fashion. One possibility is that androgens broaden the EOD pulse duration by acting on the pacemaker neurons, thereby effecting a change in pacemaker firing frequency, and that the change in EOD pulse duration is due to an activity-dependent process. To determine whether androgens can alter pulse duration despite a stable pacemaker nucleus firing frequency, we implanted small doses of dihydrotestosterone in the electric organ. We found that androgen implants increased EOD pulse duration, but did not influence EOD frequency. In addition, using immunocytochemistry, we found that electrocytes label positively with an androgen receptor antibody. While it is not known on which cells androgens act directly, together these experiments suggest that they likely act on the electrocytes to increase EOD pulse duration. Since pulse duration is determined by electrocyte action potential duration and ionic current kinetics, androgens may therefore play a causative role in influencing individual variation and sexual dimorphism in electrocyte electrical excitability, an important component of electrocommunicatory behavior.     

The relationship between the frequency of self-stimulation and parameters of the stimulus]

The dependence of self-stimulation frequency on stimulation parameters (current intensity, stimulation frequency, pulse duration, duration of pulse bursts) was studied in fifteen rats with monopolar electrodes implanted in the lateral hypothalamus, using rectangular current pulses for brain stimulation. All the experiments revealed qualitatively similar response surfaces to the combined change of stimulation frequency and pulse duration Self-stimulation frequency is connected in a non-linear way with the "specific charge" per unit of time, and in an approximately linear way, with the duration of the pulse burst. Regression equations are determined which precisely enough described the kind of response surface (R =0.7 to 0.95).     

ANALYSIS OF SOUNDS PRODUCED BY MALE PADOGOBIUS MARTENSI (PISCES,GOBIIDAE) AND FACTORS AFFECTING THEIR STRUCTURAL PROPERTIES

ABSTRACT

In this paper a detailed analysis of the physical structure of sounds produced by male Padogobius martensi is reported. Sound production occurs during courtship and inter-male agonistic encounters. Both aggressive and courtship calls are made up of rapidly repeated pulses, with a pulse repetition rate decreasing through the course of the emission. By means of computerized analysis, the pulse repetition rate, its modulation and sound duration were determined. The water temperature was found to exert a marked and significant effect on the above parameters. In particular, the temperature directly affects the pulse rate and its decrease through the course of the emission (i.e. frequency modulation) and inversely affects sound duration. By contrast, size of the calling animal does not significantly influence the sound parameters considered. Aggressive sounds last longer and have a lower pulse repetition rate than the courtship sounds. Moreover, aggressive sounds appear more variable than the courtship ones as far as pulse rate and duration are concerned.     

Possible species specific courtship sounds by two sympatric cichlid fishes in Lake Malawi, Africa

Sounds were produced by the males of two species of cichlid fishes while courting females. Each courtship sound consisted of a series of distinct pulses occurring in rapid succession. Courtship sounds produced by Tramitichromis cf. intermedius and Copadichromis conophorus were significantly different in pulse rate and individual pulse durations. For C. conophorus calls (n=127) the mean ± sd number of pulses per call was 10 ± 3 and call duration was 181 ± 59 ms. There was a significant positive linear relationship between call duration and the number of pulses (r²=0.912, p < 0.001). The dominant frequency of the pulses in calls was 471 ± 50 (range 372–594) Hz (n=40 calls). T. cf. intermedius also produced a pulsed courtship call; data (mean ± sd) from two male T. cf. intermedius: 9 ± 2 pulses per call and duration 199 ± 44 ms (n=20 calls). The linear regression between call duration and number of pulses was positive (r²=0.463, p=0.001). Pulse rate within calls of T. cf. intermedius compared to C. conophorus were significantly different (p=0.018). Individual pulse durations were also significantly different (p=0.043) between species. However, interpulse intervals were not significantly different (p=0.177). These cichlids produced courtship sounds that were distinct by individual pulse durations and by pulse repition rate in a call.     

Differences in sounds made by courting males of three closely related Lake Malawi cichlid species

Courtship sounds made by three sympatric cichlid species, Pseudotropheus zebra , P. callainos and an undescribed species known as P . 'zebra gold' were recorded and compared to investigate the potential role of acoustic signals in mate choice. Sounds were emitted during 'quiver' and 'circle' components of the male courtship display and consisted of rapidly repeated pulse units. Some sound variables differed significantly among species with P. callainos generally being separated from the other two species. This species produced sounds with higher peak frequency (for a given length) and lower number of pulses than P . 'zebra gold' and higher pulse durations than P. zebra . In addition, standard length was inversely related to peak frequency in both P . 'zebra gold' and P. callainos (this relation was not tested in P. zebra due to the small sample size). These differences might indicate different regimes of intraspecific sexual selection among the three species.     

Duration and frequency of a high temperature pulse affect survival of emergence-ready Megachile rotundata (Hymenoptera: Megachilidae) during low-temperature incubation

Synchronizing Megachile rotundata (F.) nesting activity with alfalfa bloom is essential for ensuring optimal pollination for alfalfa seed production. This is achieved by timing the initiation of spring bee incubation so that adults will emerge -2 wk before peak bloom. If weather conditions change so as to delay the bloom, bee managers will commonly expose the developing bees to a period of low-temperature incubation to slow their development. We have previously demonstrated survival during low-temperature incubation can be significantly increased by using a fluctuating thermal regime (FTR) where the bees receive a daily pulse at 20 degrees C. A FTR incubation protocol is composed of a number of different components, such as the base and pulse temperatures, and the duration and frequency of the pulse. In this investigation, the effect of the duration of the pulse (5-120 min) and the frequency of a pulse (twice daily to weekly) on the survival of developing M. rotundata was examined. A pulse as short as 5 min at 20 degrees C increased survival of the developing bees as compared with the constant 6 degrees C controls. Increasing the pulse duration induced a further increase in tolerance to 6 degrees C. As with the pulse duration, increasing the pulse frequency from once weekly to twice daily had a significant effect on improving the bees tolerance to low-temperature incubation. This investigation further strengthens the argument that a FTR protocol is superior to using a constant low-temperature exposure for interrupting the spring incubation of M. rotundata.     

Effects of flood frequency and duration on the allometry of community-level stem size-density distributions in a floodplain forest

? Premise of the study: Consistent with the self-thinning law of plant population ecology, Niklas et al. in 2003 proposed that stem size-density distributions (SDDs) of multispecies forest communities should change in very predictable ways as a function of the effects of past disturbances on average tree size. To date, empirical tests of this hypothesis have not been pursued in floodplain settings. ? Methods: SDDs were constructed using tree stem-size and density data from forest plots positioned along a flood frequency and duration gradient in the Upper Mississippi River floodplain. ? Key Results: As flooding (both frequency and duration) increased, several small tree species were eliminated from forest plots and the persistent species increased in their size. Consistent with the predictions of Niklas et al., these changes corresponded with overall decreases in stem density, increases in average stem size, and reductions in both the Y-intercept and slope terms of the community-level SDDs. ? Conclusions: This study adds to a growing list of examples suggesting that theories related to forest community composition and biomass must account for both the broader effects of disturbances as well as the underlying biochemical processes that regulate plant growth. Further study is needed to fully address the role different disturbance frequencies play in determining plant density, diversity, average size, and associated size\frequency distributions.     

Social regulation of electric signal plasticity in male Brachyhypopomus gauderio

In animal communication, the social context that elicits particular dynamic changes in the signal can provide indirect clues to signal function. Female presence should increase the expression of male signal traits relevant for mate-choice, while male presence should promote the enhancement of traits involved in male-male competition. The electric fish Brachyhypopomus gauderio produces a biphasic electric pulse for electrolocation and communication. Pulse amplitude predicts the signaler’s body size while pulse duration predicts circulating androgen levels. Males enhance pulse amplitude and duration when the numbers of males and females increase simultaneously. Here we tested the relative effects of female presence and male presence on male signal enhancement, and whether the size of the male competitor affected this enhancement. We found that male presence drives the enhancement of both pulse amplitude and second phase duration, independently of the size of the male competitor. Female presence induces the enhancement of pulse duration, but not pulse amplitude. These data suggest that males probably attend to information about a competitor’s body size coded by pulse amplitude and attend to aggressiveness coded by a competitor’s pulse duration, both potential predictors of fight outcome. Females may be primarily concerned about information on reproductive condition coded by pulse duration.