Yezhong Tang

A novel female call incites male-female interaction and male-male competition in the Emei music frog, Babina daunchina

In anurans, females generally remain silent during mating or only produce calls of very low intensity before mating. Consequently the functions of female calls are not as well understood as those produced by males. We investigated a novel female call produced during mating in the Emei music frog. The functions of the female call during reproductive behaviours were evaluated by field and seminatural playback experiments. During mating, low-intensity female calls (approximately 3.2 s in duration) alternated with male sexual movements (approximately 1.34 s in duration). Female calling was sometimes prolonged when we interrupted male movements, which is consistent with the idea that female calls may stimulate male sexual activity and perhaps facilitate ovulation. In their natural environment, Babina males vocalize and mate in well-hidden underground nests. Field playback experiments showed that female calls significantly increased the rate of male advertisement calling which may help females locate males. Males also showed significant positive phonotactic responses to playback of female calls, and increased aggressive call production and other aggressive behaviours which females may use as cues for mate selection.

Real estate ads in Emei music frog vocalizations: female preference for calls emanating from burrows

During female mate choice, both the males phenotype and resources (e.g. his nest) contribute to the choosers fitness. Animals other than humans are not known to advertise resource characteristics to potential mates through vocal communication; although in some species of anurans and birds, females do evaluate male qualities through vocal communication. Here, we demonstrate that calls of the male Emei music frog (Babina dauchina), vocalizing from male-built nests, reflect nest structure information that can be recognized by females. Inside-nest calls consisted of notes with energy concentrated at lower frequency ranges and longer note durations when compared with outside-nest calls. Centre frequencies and note durations of the inside calls positively correlate with the area of the burrow entrance and the depth of the burrow, respectively. When given a choice between outside and inside calls played back alternately, more than 70 per cent of the females (33/47) chose inside calls. These results demonstrate that males of this species faithfully advertise whether or not they possess a nest to potential mates by vocal communication, which probably facilitates optimal mate selection by females. These results revealed a novel function of advertisement calls, which is consistent with the wide variation in both call complexity and social behaviour within amphibians.

Geographic variation in the advertisement calls of Gekko gecko in relation to variations in morphological features: implications for regional population differentiation

Geographic variations in vocalizations and morphological characteristics of the tokay gecko (Gekko gecko L.) complex were identified using subjects recorded and/or collected in China and Southeast Asia. Populations in south China and northeast Vietnam (the black tokay) were compared with those in Thailand, Laos and south Vietnam (the red tokay). Red tokays possess gray- or dark green-colored skin with brick red spots interspersed on the dorsum, while black tokays possess dark-green skin with black spots or spots of other colors except brick red. Each group produces advertisement calls which consist of distinct acoustic phases. In both groups the first call phase consists of a series of pulses and the second phase consists of a series of two-note syllables. Only red tokays produce a third phase consisting of single notes. Frequency modulation patterns were profoundly different for call elements produced between the two groups. Calls of the black but not red tokay exhibit intricate frequency modulated elements with silent periods between pulses in the first phase and between syllables in the second phase. In the red tokay little or no frequency modulation was observed and no silent intervals were found between pulses or syllables. For both groups the acoustics of the pulses produced in the first phase varied among animals, suggesting it may function for individual identification while the second phase appears to identify the group (red vs black tokay). Thus the tokay complex has become differentiated geographically not only in terms of morphological characteristics but also in terms of call acoustics.

Acoustic Analysis of the Advertisement Calls of the Music Frog, Babina daunchina

Abstract The acoustic structure of 18 male advertisement calls of the “music frog” (Babina daunchina), indigenous to the Emei mountain area of Sichuan province in southwest China was analyzed. Previous results showed that Babina typically call from within hidden burrows made by the males and must rely strongly on acoustic information for mate choice. Functioning ecologically as nests, burrows are used for mating, egg-laying, and pre- and postembryonic development. Male Babina calls are spectrally and temporally complex consisting of a sequence of 3–8 notes. Each note consists of a stack of frequency bands, which are nearly integer multiples of the fundamental residue. For all calls the fundamental frequency of successive notes increases monotonically. Moreover, there is a negative correlation between the lowest harmonic (F0) value of the first call note and the increments in fundamental frequency between notes in the same call, implying that constraints exist in the production mechanism. Hierarchical cluster and multidimensional scaling analysis of 29 temporal and spectral call parameters indicate that most of the variance between calls and between males is accounted for by three clusters of call features. The first includes 19 tightly correlated temporal and modulation features including note durations and modulation patterns and total call duration. The second cluster includes the successively increasing fundamental frequencies of the call notes and may reflect that individual males can alter fundamental frequency from call to call. The third cluster includes the dominant frequency bands in calls and may reflect the filter properties of each males burrow.

Electroencephalogram bands modulated by vigilance states in an anuran species: a factor analytic approach

Dramatic changes in neocortical electroencephalogram (EEG) rhythms are associated with the sleep–waking cycle in mammals. Although amphibians are thought to lack a neocortical homologue, changes in rest–activity states occur in these species. In the present study, EEG signals were recorded from the surface of the cerebral hemispheres and midbrain on both sides of the brain in an anuran species, Babina daunchina, using electrodes contacting the meninges in order to measure changes in mean EEG power across behavioral states. Functionally relevant frequency bands were identified using factor analysis. The results indicate that: (1) EEG power was concentrated in four frequency bands during the awake or active state and in three frequency bands during rest; (2) EEG bands in frogs differed substantially from humans, especially in the fast frequency band; (3) bursts similar to mammalian sleep spindles, which occur in non-rapid eye movement mammalian sleep, were observed when frogs were at rest suggesting sleep spindle-like EEG activity appeared prior to the evolution of mammals.

Circadian Rhythm of Calling Behavior in the Emei Music Frog (Babina daunchina) is Associated with Habitat Temperature and Relative Humidity

Generally, the function of vocalizations made by male anurans are to attract females or defend resources. Typically, males vocalize in choruses during one or more periods in a twenty-four-hour cycle, which varies, however, among species. Nevertheless, the causal factors influencing circadian variations of calling patterns in anuran species are not clear. In this study, male chorus vocalizations were monitored in the Emei music frog (Babina daunchina) for 17 consecutive days during the breeding season, while its habitat air temperature and relative humidity in the course of experiments were measured as well. The results revealed that the circadian calling patterns were characterized by two periods of peak vocalization, which were observed from 0500 h to 0700 h and from 1300 h to 2000 h, while the lowest activity period was found from 2100 h to 2200 h. Both calls/h and notes/h were positively correlated with air temperature and negatively with relative humidity. Overall, our data indicate that the Emei music frogs (B. daunchina) could regulate their vocal activities based on the changes of physical micro-environment (e. g., temperature or humidity) to maximize reproductive success.

Reduced Performance of Prey Targeting in Pit Vipers with Contralaterally Occluded Infrared and Visual Senses

Both visual and infrared (IR) senses are utilized in prey targeting by pit vipers. Visual and IR inputs project to the contralateral optic tectum where they activate both multimodal and bimodal neurons. A series of ocular and pit organ occlusion experiments using the short-tailed pit viper (Gloydius brevicaudus) were conducted to investigate the role of visual and IR information during prey targeting. Compared with unoccluded controls, snakes with either both eyes or pit organs occluded performed more poorly in hunting prey although such subjects still captured prey on 75% of trials. Subjects with one eye and one pit occluded on the same side of the face performed as well as those with bilateral occlusion although these subjects showed a significant targeting angle bias toward the unoccluded side. Performance was significantly poorer when only a single eye or pit was available. Interestingly, when one eye and one pit organ were occluded on opposite sides of the face, performance was poorest, the snakes striking prey on no more than half the trials. These results indicate that, visual and infrared information are both effective in prey targeting in this species, although interference between the two modalities occurs if visual and IR information is restricted to opposite sides of the brain.

The biological significance of acoustic stimuli determines ear preference in the music frog

ABSTRACT Behavioral and neurophysiological studies support the idea that right ear advantage (REA) exists for perception of conspecific vocal signals in birds and mammals. Nevertheless, few studies have focused on anuran species that typically communicate through vocalization. The present study examined the direction and latencies of orientation behaviors in Emei music frogs (Babina daunchina) produced in response to six auditory stimuli emitted by a speaker placed directly behind the subjects. The stimuli included male advertisement calls produced from within burrow nests, which have been shown to be highly sexually attractive (HSA), calls produced from outside burrows, which are of low sexual attractiveness (LSA), screech calls produced when frogs are attacked by snakes, white noise, thunder and silence. For all sound stimuli except the screech, the frogs preferentially turned to the right. Right ear preference was strongest for HSA calls. For the screech and thunder stimuli, there was an increased tendency for subjects to move further from the speaker rather than turning. These results support the idea that in anurans, right ear preference is associated with perception of positive or neutral signals such as the conspecific advertisement call and white noise, while a left ear preference is associated with perception of negative signals such as predatory attack. Highlighted Article: Right ear advantage is demonstrated behaviorally in an anuran through an orientation task, which shows that differences in bio-significance induce variable responses, suggesting orientations are affected by mating strategy and emotion processing.

Mating signals indicating sexual receptiveness induce unique spatio-temporal EEG theta patterns in an anuran species.

Female mate choice is of importance for individual fitness as well as a determining factor in genetic diversity and speciation. Nevertheless relatively little is known about how females process information acquired from males during mate selection. In the Emei music frog, Babina daunchina, males normally call from hidden burrows and females in the reproductive stage prefer male calls produced from inside burrows compared with ones from outside burrows. The present study evaluated changes in electroencephalogram (EEG) power output in four frequency bands induced by male courtship vocalizations on both sides of the telencephalon and mesencephalon in females. The results show that (1) both the values of left hemispheric theta relative power and global lateralization in the theta band are modulated by the sexual attractiveness of the acoustic stimulus in the reproductive stage, suggesting the theta oscillation is closely correlated with processing information associated with mate choice; (2) mean relative power in the beta band is significantly greater in the mesencephalon than the left telencephalon, regardless of reproductive status or the biological significance of signals, indicating it is associated with processing acoustic features and (3) relative power in the delta and alpha bands are not affected by reproductive status or acoustic stimuli. The results imply that EEG power in the theta and beta bands reflect different information processing mechanisms related to vocal recognition and auditory perception in anurans.

Eye size variation reflects habitat and daily activity patterns in colubrid snakes

The functioning of the vertebrate eye depends on its absolute size, which is presumably adapted to specific needs. Eye size variation in lidless and spectacled colubrid snakes was investigated, including 839 specimens belonging to 49 genera, 66 species and subspecies. Variations of adult eye diameters (EDs) in both absolute and relative terms between species were correlated with parameters reflecting behavioral ecology. In absolute terms, eye of arboreal species was larger than in terrestrial and semiaquatic species. For diurnal species, EDs of terrestrial species do not differ from semiaquatic species; for nocturnal species the ED of terrestrial species is larger than fossorial species but not different from semiaquatic species. In relative terms, ED did not differ significantly by habitat for diurnal species. Although the ED of terrestrial species is larger than fossorial species there were no differences for nocturnal species between semiaquatic and fossorial snakes. In contrast to other vertebrates studied to date, colubrid EDs in absolute and relative terms are larger in diurnal than in nocturnal species. These observations suggest that among colubrid snakes, eye size variation reflects adaptation to specific habitats, foraging strategies and daily activities, independently of phylogeny. J. Morphol. 2012.