Male singing behaviour and female presence in the territory in whitethroats Sylvia communis

Unmated male songbirds usually change their vocal behaviour when females enter their territories. Either the males court the females by changing the rate or pattern with which their normal long-ranging full songs are emitted, or they shift to special displays and long- or short-ranging vocalisations. In this study we quantified how female presence and behaviour affect the singing behaviour of male whitethroats. In the presence of a female the male frequently performed song flights, maybe to locate the female before it was courted, with sequences of diving-song displays. The courtship was interrupted by periods of perch songs. Female dscharp calls and short movements made the males initiate or resume courtship, whereas short horizontal jumps made the males intensify their courtship. Overall, the males changed their dual-function song activity in females' presence by emitting fewer perch songs and more flight songs. The quiet diving songs were only emitted during direct courtship of a female. The song types emitted immediately before, during, and after courtship are all highly variable, thus allowing for a quick assessment of the male's song repertoire. The courtship was also interrupted by periods of male woid calling, a call that is known to have a deterring effect on rival males. Bouts of woid calls were usually followed by song flights, again probably to locate the female that might have moved out of sight, or maybe to locate potential rival intruders. The latter was supported by an increased intrusion rate during female presence. Communicated by P. McGregor     

Behavioral Sequence Leading to Sexual Isolation Between <Emphasis Type="Italic">Drosophila ananassae</Emphasis> and <Emphasis Type="Italic">D. pallidosa</Emphasis>

Drosophila ananassae and D. pallidosa are closely related, sympatric species that lack postmating isolation. Sexual isolation has been considered important in maintaining them as independent species. To clarify the behavioral processes leading to sexual isolation, we analyzed behavioral sequences and examined the effect of courtship song on mating success and on behaviors of both sexes by surgically removing male wings (song generators), female aristae (song receivers), or female wings (means of fluttering). We found that heterospecific courtship songs evoked female wing fluttering, whereas conspecific courtship song did not. Furthermore, female wing fluttering made courting males discontinue courtship. These findings suggest that strong sexual isolation is achieved through the following behavioral sequence: heterospecific song→female wing fluttering→courtship discontinuation.     

Broad Selectivity for Courtship Song in the Cricket Gryllus bimaculatus

Various characteristics of a long‐distance acoustic signal have been shown to vary to different degrees. It has been suggested that female preferences based on stable song parameters are stabilising or weakly directional, and preferences based on variable parameters are strongly directional. We tested this hypothesis based on a short‐distance signal (courtship song) produced by the field cricket, Gryllus bimaculatus. We studied the degree of variability of different courtship song parameters and the behavioural importance of several parameters using synthesised song models in playback experiments. We found that most of the courtship song elements of G. bimaculatus were quite variable (coefficient of variation, CV, in the range of 20–53%). The most variable parameter of the courtship song was the relative amplitude of two elements: high‐amplitude ticks and low‐amplitude pulses. Because songs containing only ticks (of rare occurrence) appeared to be more effective than songs with both ticks and pulses (of frequent occurrence), we consider female preferences to be directional. Alteration of less variable traits, such as the carrier frequency and duration of ticks (CV = 20–25%), had a different effect on female responsiveness. The synthesised songs with different carrier frequencies of ticks were as attractive to females as the positive control (courtship of muted males accompanied by playback of the recorded song). Altering the duration of ticks had a crucial effect on the female response rate, decreasing female responsiveness to the level observed in the negative control (courtship of muted males). Thus, we did not find a strong relationship between the variability of individual song parameters and their potential importance in song recognition and the evaluation of male quality. The partial inconsistency of our results with the data of other authors may be due to different patterns of past and current selection on long‐distance and short‐distance acoustic signals.     

The Effect of Male Competition on the Courtship Song of Drosophila melanogaster

The courtship song of Drosophila has been extensively used as a model system for studies of sexual selection and species recognition. Traditionally, the courtship song has been recorded from males placed individually with a female. However, under natural conditions females are exposed to multiple courting males, and the effect of their joint signal on mate recognition by the female is not yet understood. Here, we recorded the courtship behavior of D. melanogaster males singing either individually to a female lpar;1:1) or in the presence of an additional male lpar;2:1). We compared the structure of the male song in the two experimental designs. Our results show that when two males courted a female their songs could overlap each other. Males produced a significantly different signal in the presence of competition; the duration of each song component was significantly shorter and the rate of singing was markedly lower. The present study demonstrates that male competition can dramatically alter the acoustic signal detected by the female.     

A neural network-based analysis of acoustic courtship signals and female responses in <Emphasis Type="Italic">Chorthippus biguttulus</Emphasis> grasshoppers

In many animal species, male acoustic courtship signals are evaluated by females for mate choice. At the behavioural level, this phenomenon has been well studied. However, although several song characteristics have been determined to affect the attractiveness of a given song, the mechanisms of the evaluation process remain largely unclear. Here, we present a simple neural network model for analysing and evaluating courtship songs of Chorthippus biguttulus males in real-time. The model achieves a high predictive power of the attractiveness of artificial songs as assigned by real Chorthippus biguttulus females: about 87% of the variance can be explained. It also allows us to determine the relative contribution of different song characteristics to overall attractiveness and how each of the song components influences female responsiveness. In general, the obtained results closely match those of empirical studies. Therefore, our model may be used to obtain a first estimate of male song attractiveness and may thus complement actual testing of female responsiveness in the laboratory. In addition, the model allows including and testing novel song parameters to generate new hypotheses for further experimental studies. The supplemental material of this article contains the article’s data in an active, re-usable format.     

Preexisting behavior facilitated the loss of a sexual signal in the field cricket Teleogryllus oceanicus

Behavioral preadaptations can provide an accommodating environmentin which novel morphological characters may be selected. A veryrecent morphological mutation, flatwing, has caused the lossof male song in field crickets (Teleogryllus oceanicus) fromthe Hawaiian island of Kauai. Previous studies in this and relatedspecies have shown that females require male courtship songto mount males, but flatwing T. oceanicus males still achievematings. Females from Kauai may have a relaxed requirement formale courtship song, or flatwing males may compensate for theirinability to sing by altering other courtship behaviors. Wetested whether male courtship and female responses to male courtshipwere preadapted in a way that facilitated the spread of themale wing mutation or if parallel changes in male courtshipand female responses accompanied the mutation. We performedmating trials in 2 captive-bred populations to assess how matingbehavior varied depending on the presence or absence of courtshipsong playback. The first was an ancestral population from Kauaiestablished prior to the emergence of the flatwing mutation,and the second was derived from Kauai after the mutation becameprevalent. Mating behaviors did not differ qualitatively orquantitatively between the ancestral and current populations,and females from both accepted males for mating in the absenceof courtship song. Our results provide direct evidence thata mechanism allowing flatwing males to mate with females wasin place before the mutation actually arose on Kauai and demonstratehow preexisting behavior facilitated the rapid spread of a novelmorphological mutation.     

Courtship signals and mate choice of the flies of inbred Drosophila montana strains

We studied genetic variation in fly mating signals and mate choice in crosses within and between inbred strains of Drosophila montana. Male songs and the cuticular hydrocarbons of both sexes as well as some of the flies’ behavioural traits differed significantly between strains. This did not, however, cause sexual isolation between strains. In fact, courtship was shorter if the female was courted by a male of a foreign strain than when courted by their own male. Heterosis was found for courtship duration and the carrier frequency of male song. Diallel analysis of male song revealed additive genetic variation in four out of the five traits studied. Two traits showed dominance variation and one of these, carrier frequency, expressed unidirectional dominance with alleles for higher carrier frequency being dominant. Direction of dominance in carrier frequency was the same as the direction of sexual selection exercised by D. montana females on this trait, which suggests that sexual selection could be a driving force in the evolution of song towards a higher carrier frequency.     

The importance of calling song and courtship song in female mate choice in the variable field cricket

Male field crickets produce calling songs, courtship songs, tactile signals and chemical signals. Although calling songs are known to play an important role in female mate choice, the importance of the other signals in mate choice is poorly understood. In the variable field cricket, Gryllus lineaticeps, females select mates, in part, based on variation in male calling song. Females prefer higher chirp rates, a trait which is partially dependent on male nutrient intake, and females prefer longer chirp durations, a trait which appears to be independent of male nutrient intake. We tested whether females also have preferences based on variation in male courtship song, and whether the structure of male courtship song varies with nutrient intake. First, we reexamined female preference for calling song chirp rate. Then, we examined: (1) female preference based on courtship song chirp rate; (2) the relative importance of calling song and courtship song chirp rate; (3) the nutrition dependence of courtship song chirp rate; and (4) the correlation between calling song and courtship song chirp rate. As reported previously, females preferred higher calling song chirp rates, and in addition, preferred higher courtship song chirp rates. Females were more likely to switch from a speaker broadcasting more attractive calling song to a speaker broadcasting less attractive calling song when the attractive calling song was associated with an unattractive courtship song than when it was associated with an attractive courtship song. Preferences based on courtship song may thus cause females to alter the choices that they made based on calling song. Males that received greater nutrients did not produce higher courtship song chirp rates. There was no correlation between calling song and courtship song chirp rate. As a result, the two traits may provide information to females about different aspects of male quality. Copyright 2000 The Association for the Study of Animal Behaviour.     

Vibrational communication and mating behaviour of Dichelops melacanthus (Hemiptera: Pentatomidae) recorded from loudspeaker membranes and plants

Vibrational communication is important for successful mating in various stink bugs species. The vibrational signals from males and females of Dichelops melacanthus Dallas (Hemiptera: Pentatomidae) are recorded from a nonresonant substrate (i.e. a loudspeaker membrane) to characterize the temporal and spectral properties of these vibrational signals, as well as on a resonant substrate (i.e. bean plants) to obtain information about how these signals are altered when they are transmitted through the plants. On the loudspeaker membrane, D. melacanthus males and females emit only one male or one female song, respectively. However, when the insects are placed on bean leaves, a more complex repertoire is recorded, with three different songs for each sex. The first female and male songs appear to have calling functions and the third male and female songs are emitted during courtship. The second female and male songs are emitted after the first song, although their functions in mating behaviour are not clear. The identified repertoire is similar to those of other Neotropical stink bugs, starting with songs 1 and 2 and developing into song 3. Frequency modulation is observed in the female songs recorded from the loudspeaker membrane and the plants. The signals recorded from plants present higher harmonic peaks compared with the signals recorded from the loudspeaker membrane. The presence of species and sex‐specific songs during mating confirms the important role of vibrational communication in mate location and recognition. The temporal and spectral characteristic signals are influenced by the substrate used to record the songs emitted by D. melacanthus.     

The structure and function of songs emitted by southern green stink bugs from Brazil, Florida, Italy and Slovenia

Nezara viridula (L.) (Pentatomidae: Heteroptera) from Brazil, Florida, Italy and Slovenia, communicate by vibratory songs associated with long‐range calling and close‐range courting, rivalry and repelling. Each song is composed of spectrally and temporally different units. Spectrally different pulses of duration less than 300 ms are present in the male calling song. The female calling song is characterized by pulse trains composed of pulses shorter than 150 ms and pulse trains composed of a longer (> 700 ms) and shorter (< 250 ms) pulse. Shorter and longer pulses have different spectral characteristics. The male and female courtship songs are characterized by fusion of shorter (< 150 ms) pulses into a pulse train usually followed by a shorter (< 200 ms) postpulse in the case of the male courtship song. The female repelling song is a several seconds long vibration of irregular temporal structure. The short (< 400 ms) male rival song pulses are frequency modulated. The dominant frequency peaks of the songs investigated lie between 70 and 130 Hz. The dominant frequency and the microstructure of song spectra show no population specificity. The average duration varies more in calling than in courtship songs. The repetition time varies extensively in songs of different populations. Normal communication followed by copulation was observed between mates from Slovenia and Brazil and between mates from Florida and Italy. The potential role of different temporal and spectral parameters for species recognition and mate location is discussed in view of the expected distortion of the characteristic signal structure during transmission through plants.     

Species and sex-specific songs and courtship behaviour in the genus Zaprionus (Diptera-Drosophilidae)

Courtship behaviour and songs of six Zaprionus species show differences not only between species but also between sexes. Courtship behaviour differs from that in the related genus Drosophila. In most species, males produce two song types which may alternate or be repeated. Singing occurs during courtship displays, mounting, after copulation and briefly during male-to-male interactions. Females produce a loud whine and body rocking movements in refusal but have a species-specific pulsed song produced during normal courtship which differs from the conspecific male song. One species produces an irregular male song but a regular female song. Sex-specific songs may have selective advantages but pose problems for the sensory template hypothesis.     

Songs of Holcostethus strictus (Fabricius): a different repertoire among landbugs (Heteroptera: Pentatomidae)

Songs emitted during mating by male and female Holcostethus strictus were recorded as substrate vibrations. Spectra of the vibrational signals have a dominant frequency peak between 100 and 260 Hz and in this respect reflect the general characteristic of the family Pentatomidae. Songs of H. strictus differ from the song repertoire of the southern green stink bug Nezara viridula (L.) (Pentatomidae) in many respects. The female calling and courtship songs differ in echeme and phrase duration. The male calling song is composed of spectrally different subunits. The male courtship song is characterised by three types of spectrally and temporally different echemes. The male copulatory song is composed of echemes of two types, which constitute a phrase of less regular temporal structure. In H. strictus, males start to sing first and female songs are less complex than in N. viridula. The female calling song is evoked by male calling and does not trigger male response. The female and male courtship song phrases are superimposed on one another and we have not observed any obvious regularity in their exchange. The possible role of different songs in H. strictus is discussed and compared with that in other pentatomide landbug species.     

THE ROLE OF COURTSHIP SONGS IN REPRODUCTIVE ISOLATION AMONG POPULATIONS OF GREEN LACEWINGS OF THE GENUS CHRYSOPERLA (NEUROPTERA: CHRYSOPIDAE)

Male and female lacewings tremulate during courtship, establishing duets that always precede copulation. Three distinct courtship songs are found in populations of the green lacewing Chrysoperla plorabunda (P1, P2 and P3 song morphs). Analysis of five features of the songs for individuals collected from Connecticut, Idaho, Oregon and California showed few differences within song morphs, but sympatric song morphs differed significantly in temporal features of the songs and their mode of presentation. Playback experiments using recorded songs were performed on females with all possible sympatric and allopatric combinations of females and recorded songs. The results showed that females strongly prefer to duet with recordings of males of their own song type and usually showed no responses to songs of other types. Thus, song differences are effective barriers to reproduction between the sympatric morphs. Our results support the hypothesis that the three song morphs are true biological species.     

Genetics of sexual isolation based on courtship song between two sympatric species: Drosophila ananassae and D. pallidosa

Sexual isolation has been considered one of the primary causes of speciation and its genetic study has the potential to reveal the genetics of speciation. In Drosophila, the importance of courtship songs in sexual isolation between closely related species has been well investigated, but studies analysing the genetic basis of the difference in the courtship songs associated with sexual isolation are less well documented. Drosophila ananassae and Drosophila pallidosa are useful for studies of sexual isolation, because of their sympatric distribution and absence of postmating isolation. Courtship songs are known to play a crucial role in sexual isolation between these two species, and the female discrimination behaviour against the courting male has been revealed to be controlled by a very narrow region on the second chromosome. In this study we investigated the genetic basis controlling the song differences associated with their sexual isolation, using intact and wingless males with chromosomes substituted between species. The results obtained from F₁ hybrid males between these species indicate the dominance of the song characters favoured by D. pallidosa females. In addition, the results obtained from backcross F₂ males indicate that chromosome 2 had a major effect on the control of the song characters associated with sexual isolation.     

Sex-specific spectral tuning for the partner's song in the duetting bushcricket Ancistrura nigrovittata (Orthoptera: Phaneropteridae)

The song of the male bushcricket Ancistrura nigrovittata consists of a sequence of verses. Each verse comprises a syllable group, plus, after about 400 ms a single syllable serving as a trigger for the female response song. The carrier frequency of the male song spectrum peaks at around 15 kHz, while the female song peaks at around 27 kHz. The thresholds of female responses to models of male songs are lowest for song frequencies between 12 and 16 kHz and therefore correspond to the male song spectrum. The threshold curve of the female response to the trigger syllable at different frequencies has the same shape as the tuning for the syllable group. Phonotactic thresholds of male Ancistrura nigrovittata to synthetic female responses at different frequencies are lowest between 24 and 28 kHz and thereby correspond to the female song spectrum and clearly differ from female response thresholds. Activity of the tympanic fibre bundle of both sexes is most sensitive between 15 and 35 kHz and therefore not specifically tuned to the partner's song. Individual behavioural thresholds have their minimum within 10 dB of the values of tympanic thresholds.     

Does courtship behavior contribute to species-level reproductive isolation in field crickets?

Reproductive behavior influences gene flow within and amongspecies; thus, sexual selection may be a major contributor tothe maintenance of species, and possibly their formation. HereI experimentally manipulate the courtship interactions of thefield crickets Gryllus rubens and G. texensis to examine thepotential of close-range courtship interactions to limit interspecificgene flow. Responses of males to females and of females to malecourtship song and males per se were examined for four pairedsympatric and allopatric populations. Male G. rubens were morelikely to court conspecific females, but male G. texensis courtedfemales of both species equally. If paired with conspecificmales, female G. rubens and G. texensis both preferred conspecificcourtship song. In none of these comparisons were the responsesof males or females from allopatry different from those in sympatry.There was an asymmetry of courtship response across both sexand species: male G. rubens were more discriminating than maleG. texensis, whereas female G. texensis were more discriminatingthan female G. rubens. Despite significant preferences for conspecifics,the net effect of courtship interactions would appear to limitinterspecific gene flow only weakly. These results are consistentwith courtship behavior evolving under the influence of sexualselection and only indirectly promoting species integrity.     

A narrow hybrid zone between the grasshoppers Stenobothrus clavatus and Stenobothrus rubicundus (Orthoptera: Gomphocerinae): female preferences for courtship songs

Two grasshopper species, Stenobothrus rubicundus and Stenobothrus clavatus, were previously shown to hybridize in a narrow contact zone on Mount Tomaros in northern Greece. The species are characterized by complex and completely different courtship songs. In the present study, we investigated female preferences for the courtship songs of S. rubicundus, S. clavatus and hybrids in playback experiments. Playback of the courtship songs revealed assortative preferences in females of the parental species: they significantly more often preferred the songs of conspecific males. Hybrid females showed a lower selectivity than parental females, responding somewhat equally eager to playback of the songs of S. clavatus, S. rubicundus, and natural hybrid song, although less actively to the F₁ hybrid song. The results suggest that hybrid males may lose to males of parental species, whereas hybrid females would even have an advantage over parental females. Comparison of responses of females from allopatric populations and Mount Tomaros to different song types shows no evidence for reinforcement. Asymmetry found in female preferences may have implications for the structure of the hybrid zone. © 2013 The Linnean Society of London     

雄性稻绿蝽对雌性鸣唱反应的物种特异性

雌性稻绿蝽的鸣唱开始了在基质中产生的通讯并引起雄性不同的特定反应。在两种自然情况下 ,我们检验了雄性稻绿蝽对N viridula ,Thyantapallidovirens和Thyantacustatoraccerra个体鸣唱刺激反应的物种特异性水平 ,并对反应强度和同种及异种刺激性鸣唱的时间特性进行了相关分析 ,证明雄性求偶鸣唱的发送和震动源的定位是最具物种特异性的反应。然而 ,即便是在这个水平上 ,雄性稻绿蝽不能将同种雌性个体的鸣唱与T .custatoraccera的第二个雄性个体的鸣唱区分开来 ,后者与前者有相似的脉冲持续时间和重复时间值。本文也讨论了涉及交配行为鸣唱期的有关信号的物种特定性的概念     

Frequency as a releaser in the courtship song of two crickets,Gryllus bimaculatus (de Geer) and Teleogryllus oceanicus: a neuroethological analysis

1. The courtship behavior of male field crickets, Gryllus bimaculatus (De Geer) and Teleogryllus oceanicus, is a complex, multimodal behavioral act that involves acoustic signals (a courtship song; Fig. 1A,B). The dominant frequency is 4.5 kHz for T. oceanicus song (Fig. 1A) and 13.5 kHz for G. bimaculatus (Fig. IB).
2. When courting males are deprived of their courtship song by wing amputation, their courtship success declines markedly but is restored when courting is accompanied by tape-recordings of their courtship songs or a synthetic courtship song with only the dominant frequency of the natural song; other naturally occurring frequency components are ineffective for restoring mating success (Figs. 4, 5).
3. It has been suggested that an identified auditory interneuron, AN2, plays a critical role in courtship success. Chronic recordings of AN2 in an intact, tethered female show that AN2's response to the natural courtship song and synthesized songs at 4.5 and 13.5 kHz is similar in T. oceanicus. By contrast, in G. bimaculatus, AN2's response to the natural courtship song and synthesized song at 13.5 kHz, but not at 4.5 kHz, is similar (Figs. 2,3).
4. In behavioral experiments, playback of a 30 kHz synthetic courtship song in G. bimaculatus does not restore courtship success, yet this same stimulus elicits as strong a response from AN2 as does the normal courtship song (Fig. 6). Thus, contrary to earlier work by others, we conclude AN2 is not, by itself, a critical neural link in the courtship behavior of these two species of crickets.

     

配偶选择中“听众效应”及鸣唱对雌性灰文鸟行为的影响

配偶选择是性选择研究核心问题之一。雌性通过选择高质量的雄性配偶获得直接利益,如资源、营养和保护等,也可以通过获得高质量雄性提高后代的适合度。配偶选择研究对于研究性选择机制和进化均具有重要意义。目前,对配偶选择的研究主要集中在影响配偶选择的因素及雌性"听众效应"中雄性-雄性竞争方面。鸣唱对配偶选择的影响和雄性"听众效应"中雌性-雌性竞争的研究对于探索鸟类配偶选择中信号交流、调整的方式及选择策略均具有重要意义。以灰文鸟为对象,研究了雄性鸣唱对雌性配偶选择的影响及雄性"听众效应"对雌性灰文鸟同性竞争行为的影响进行了探讨。实验一利用双向选择装置,以配偶鸣唱(求偶鸣唱或非求偶鸣唱)和非配偶鸣唱(求偶鸣唱或非求偶鸣唱)对雌鸟进行刺激,观察雌鸟对两端鸣唱的偏爱状况。实验二主要观察雌鸟之间在无听众、听众为熟悉的雄性和听众为配偶条件下的竞争行为。结果表明,雌性灰文鸟大多偏爱配偶鸣唱,相对于配偶的非求偶鸣唱更偏爱非配偶的求偶鸣唱。求偶鸣唱比非求偶鸣唱更具有吸引力,求偶鸣唱更能刺激雌性灰文鸟配偶选择的积极性,这种积极要付出更多的时间和资源,但雌鸟可以通过选择更高质量的雄性配偶获益。在配偶雄性作为听众条件下雌鸟攻击行为最高,显著高于熟悉雄性为听众的条件下,并且两者都显著高于无听众条件下雌鸟的攻击行为。雌性灰文鸟会基于不同"听众"而对雌-雌竞争行为做出适当调整。上述研究结果对于深入理解鸟类的性选择行为机制具有重要帮助作用。