Journal articles on the topic 'Frogs/newts sexual behaviour'

In vertebrates, the relative proportion of the number of trunk and caudal vertebrae is an important determinant of body shape. While among amphibians frogs and toads show low variation in vertebrae numbers, in salamanders the numbers of trunk and caudal vertebrae vary widely, giving rise to phenotypes in the range from short-bodied and long-tailed to long-bodied and short-tailed. We analysed vertebral numbers in the family Salamandridae in a phylogenetic context and calculated the relationship between vertebral changes and changes in climate and other environmental parameters. A significant association was found between morphological change with precipitation and temperature. However, annual precipitation affected the two main groups of salamandrid salamanders differently, with trunk elongation in the terrestrial ‘true salamanders’ and tail elongation in the more aquatic ‘newts’. A - male biased - sexual dimorphism was only observed in Lissotriton vulgaris vulgaris in the number of trunk vertebrae and in Ommatotriton ophryticus and Lissotriton species for the number of caudal vertebrae. Our data indicated that the number of trunk and caudal vertebrae are highly evolvable traits with frequent evolutionary reversals. In some groups (e.g. Cynops, Lyciasalamandra, Neurergus and the Laotriton- Pachytriton-Paramesotriton clade) the number of trunk vertebrae is stable, while in many groups it is subject to change (e.g. Tylototriton). This latter, species-rich genus appears to be an excellent group to further test effects of the environment on body shape.

Courtship display characteristics are described and compared for the newts Triturus cristatus and T. marmoratus and patterns of male competitive behaviour are recognized. In interpreting the data, the operational sex ratio has to be taken into account, which was highly biased towards males in both species, more in T. marmoratus than in T. cristatus. When sexual active, males of cristatus had more encounters than males of marmoratus, whereas the latter spent more time residing mating places. The male’s display towards a female differed in time structure, variability and in behaviour characteristics. T. marmoratus display follows a fixed pattern; males succeeded better in restraining a female than males cristatus did. Courting males cristatus allowed other males to intrude. Malemale encounters were longer and playful in T. cristatus, more violent in T. marmoratus. Comparison with data from the literature indicates that courtship of T. marmoratus has more features in common with that of T. vittatus than it has with the courtship of T. cristatus. It is suggested that in the course of evolution T. marmoratus adopted a strategy of Sexual Defense by means of territoriality and overt fighting, whereas T. cristatus in contrast adopted a strategy of Sexual Interference by female mimicry. Male display components that played a major role during the adaptation of competitive strategy are identified as the “whip” behaviour in T. marmoratus and the “rocking” behaviour in T. cristatus.

Species that use communication sounds to coordinate social and reproductive behavior must be able to distinguish vocalizations from nonvocal sounds as well as to identify individual vocalization types. In this study we sought to identify the neural localization of the processes involved and the temporal order in which they occur in an anuran species, the music frog Babina daunchina. To do this we measured telencephalic and mesencephalic event-related potentials (ERPs) elicited by synthesized white noise (WN), highly sexually attractive (HSA) calls produced by males from inside nests and male calls of low sexual attractiveness (LSA) produced outside of nests. Each stimulus possessed similar temporal structures. The results showed the following: (1) the amplitudes of the first negative ERP component (N1) at ∼100 ms differed significantly between WN and conspecific calls but not between HSA and LSA calls, indicating that discrimination between conspecific calls and nonvocal sounds occurs in ∼100 ms, (2) the amplitudes of the second positive ERP component (P2) at ∼200 ms in the difference waves between HSA calls and WN were significantly higher than between LSA calls and WN in the right telencephalon, implying that call characteristic identification occurs in ∼200 ms and (3) WN evoked a larger third positive ERP component (P3) at ∼300 ms than conspecific calls, suggesting the frogs had classified the conspecific calls into one category and perceived WN as novel. Thus, both the detection of sounds and the identification of call characteristics are accomplished quickly in a specific temporal order, as reflected by ERP components. In addition, the most dynamic ERP patterns appeared in the left mesencephalon and the right telencephalon, indicating the two brain regions might play key roles in anuran vocal communication.

The ability to sense water surface waves has been described in only a few species, but across a wide taxonomic range. Water surface waves are typically used to localize prey or to avoid predators, and in some cases also for sexual communication. Here we add to the sparse knowledge of the use of this sensory modality by reporting observational and experimental evidence that wood frogs (Lithobates sylvaticus) respond to water surface waves generated by conspecifics; that there are pronounced differences in response between males and females; and that they use surface waves in a behavioural context not previously reported for anuran reproductive behaviour: sexual eavesdropping. Because the water waves that elicit the described responses are incidental by-products of calling and locomotion behaviour, we consider this an example of sexual eavesdropping rather than sexual communication. Males quickly and accurately approach a surface wave source, thus aiding in mate acquisition which in this species is mainly achieved by scramble competition. By contrast, females move away from a surface wave source. This may help them avoid sexual harassment by mate-searching males. Because it assures that only the fastest, strongest, and potentially fittest males can amplex them, it may also be a strategy for indirect mate choice by females.

AbstractTinbergen suggested there are four major aims or questions in ethology. All of these contribute to the larger single question of why animals behave as they do. Here, I emphasise one aim, to understand the evolution of behaviour. Using studies of sexual communication in túngara frogs (Physalaemus pustulosus) I attempt to illustrate how an analysis of the past evolution of behaviour can contribute to our understanding of its current function and the details of the mechanisms guiding it. I argue that integration of Tinbergen's four questions not only give us a more complete understanding of the biology of behaviour, it might be necessary to give us a correct understanding.

Abstract1. Mating and aggressive behaviour was observed in four species of dendrobatid frogs in Corcovado National Park, Costa Rica: Colostethus nubicola, Colostethus talamancae, Phyllobates vittatus and Dendrobates granuliferus. 2. Males of both species of Colostethus were more likely to respond to call playbacks than male P. vittatus or D. granuliferus. Male D. granuliferus were less likely to be found calling than males of the other species. Conspecific male-male aggression was observed in P. vittatus, but not in the other species. 3. Females were more active during courtship in P. vittatus. Female-female aggression was observed on one occasion in P. vittatus. Females were more likely to reject males than the reverse in all species. 4. These observations suggest that sexual conflict occurs in P. vittatus, but not in C. nubicola or C. talamancae.

AbstractIn acoustically advertising anurans the male courtship call elicits species-typical responses from conspecifics – usually phonotactic approach and mate choice in gravid females and an evoked vocal response in adult males. Males in several species, however, are also known to perform phonotaxis, sometimes with the same acoustic preferences as females. Female túngara frogs are known to update their phonotactic approach as male advertisement signals change dynamically in attractiveness. Here we show that males also perform such temporal updating during phonotaxis in response to dynamic playbacks. While males exhibit slower phonotactic approaches than females, their responsiveness to dynamic changes in call complexity does not differ significantly compared to females. These results demonstrate that males are sensitive to the location of preferred call types on a moment-to-moment basis and suggest that similarities between male and female sexual behaviour in anurans might often be overlooked. We suggest that anuran phonotaxis is more widespread and serves different functions in reproductive females and males. Lastly, these temporal updating results suggest that male frogs are highly selective about site selection in a chorus.

Predators often eavesdrop on sexual displays of their prey. These displays can provide multimodal cues that aid predators, but the benefits in attending to them should depend on the environmental sensory conditions under which they forage. We assessed whether bats hunting for frogs use multimodal cues to locate their prey and whether their use varies with ambient conditions. We used a robotic set-up mimicking the sexual display of a male túngara frog ( Physalaemus pustulosus ) to test prey assessment by fringe-lipped bats ( Trachops cirrhosus ). These predatory bats primarily use sound of the frog's call to find their prey, but the bats also use echolocation cues returning from the frog's dynamically moving vocal sac. In the first experiment, we show that multimodal cues affect attack behaviour: bats made narrower flank attack angles on multimodal trials compared with unimodal trials during which they could only rely on the sound of the frog. In the second experiment, we explored the bat's use of prey cues in an acoustically more complex environment. Túngara frogs often form mixed-species choruses with other frogs, including the hourglass frog ( Dendropsophus ebraccatus ). Using a multi-speaker set-up, we tested bat approaches and attacks on the robofrog under three different levels of acoustic complexity: no calling D. ebraccatus males, two calling D. ebraccatus males and five D. ebraccatus males. We found that bats are more directional in their approach to the robofrog when more D. ebraccatus males were calling. Thus, bats seemed to benefit more from multimodal cues when confronted with increased levels of acoustic complexity in their foraging environments. Our data have important consequences for our understanding of the evolution of multimodal sexual displays as they reveal how environmental conditions can alter the natural selection pressures acting on them.

Faecal analyses were used to investigate the diets of the endangered frogs Litoria nannotis, L. rheocola and Nyctimystes dayi in Tully Gorge, North Queensland. Comparisons of diet and food availability indicate that these species feed indiscriminately on a range of terrestrial and aquatic invertebrates. Changes in morphology and foraging behaviour significantly influenced diet composition and created subtle shifts in the degree of selectivity displayed in prey choice. Interspecific differences in numeric and volumetric diet composition were attributed to variations in gape size and microhabitat selection. Within the diets of L. nannotis and L. rheocola, a decline in prey selectivity observed during the dry season reflected a reduction in foraging activity. Differences in the gape size and foraging behaviour of males and females of L. nannotis were responsible for sex-specific differences in diet composition. L. nannotis also diplayed an ontogenetic shift in prey size and type. As snout–vent length increased, L. nannotis consumed fewer, but larger prey and increasingly discriminated against dipterans, dipteran larvae and hemipterans. Importantly, L. nannotis, L. rheocola and N. dayi demonstrated the capacity to compensate for fluctuations in food availability by feeding on less lucrative prey.

AbstractAt a pond in Kottenforst, Bonn, West Germany, the calling period of the water frog Rana lessonae began on the first of May and ended by the end of June, 1983. The population is of the mixed type: 80-85 % of the individuals are classified as R. lessonae, the rest as R. esculenta. The reproductive period is subdivided into 3 successive phases: pre-spawning, spawning and post-spawning. Various exogenous factors, such as temperature, rainfall and sunlight, influence the reproductive period, and they particularly affect calling activity. The male frogs do not produce mating calls when the water temperature is below 14°C, or above 26°C. Female frogs prefer sunny places in the water during the spawning phase. Sexual activity is more intense in male R. lessonae than in male R. esculenta. Medium- and large-size male R. lessonae are more successful than small males in choosing suitable territories and in maintaining of amplexus with females. Male R. lessonae give four basic types of calls-mating call, two territorial calls and release call-and in addition two transitional calls. The basic types are given throughout the calling period, whereas the transitional calls are not. An increase in water temperature induces a decrease in call duration, intercall interval and pulse-group duration of the mating call. On the other hand, the frequencies and the repetition rate of the pulse groups are raised. Similarly, the duration of both territorial calls decreases at higher water temperatures, whereas their dominant frequencies are subjected to a notable increase. Body size has a prominent effect on the mating call. The number of pulses per pulse group and the different frequencies of the call decrease with increasing male body length. The lower pitch in the mating call produced by medium- and large-size males is assumed to play a role in their mating-success. The repetition rate of pulses and the dominant frequency in the territorial calls decrease as the body size of the frogs increases.

Among the endemic radiation of mantellid frogs from Madagascar, the recently described genus Tsingymantis is one of the most enigmatic lineages considered to belong to the subfamily Mantellinae (Glaw et al. 2006). Mantellines are characterized by several derived characters related to reproduction: As far as known, they all deposit their eggs outside of the water (Blommers-Schlösser & Blanc 1991; Glaw & Vences 2006). They also lack a strong mating amplexus, and associated to this derived mating behaviour, males also have no nuptial pads or release calls (Blommers-Schlösser & Blanc 1991; Glaw & Vences 1994). In addition, males in the Mantellinae (except for Boehmantis microtympanum and Spinomantis microtis; see Andreone & Nussbaum 2006) have specialized macroglands on the ventral shanks (usually called femoral glands), and in the genera Gephyromantis and Mantidactylus, they often have larger relative tympanum sizes (Glaw & Vences 2006).

Abstract The morphometry and diet of two sympatric species of Chironius (C. flavolineatus and C. quadricarinatus) from Brazilian Cerrado are described. The two snake species differ in external morphology, as Chironius flavolineatus was the largest species (body, tail and eyes) whereas C. quadricarinatus the heaviest. Each species also showed marked sexual size dimorphism. In terms of dietary ecology, both species feed exclusively on frogs with a heavy preference for hylids and may have tendency to eat small items, as noticed in other colubrine species. These two snake species showed a brownish colour pattern and exhibited no ontogenetic variation, suggesting that juveniles and adults use similar substrates. Chironius flavolineatus and C. quadricarinatus present a semi-arboreal habit, with active foraging behaviour, feeding in the ground most of time. Chironius flavolineatus uses higher vegetation for resting and, based on morphological results, seems to be more arboreal than C. quadricarinatus.

Vocalizations and reproductive activity of two Leptodactylus labyrinthicus populations were studied from Jun/2001 to Feb/2003 in the State of São Paulo, Brazil. Observations began at dusk and ended around 2300 h. Occasionally individuals were monitored throughout the night. Data on reproductive period, calling sites, adult snout-vent length (SVL), oviposition sites, and oviposition period was collected. Leptodactylus labyrinthicus had an extended breeding period associated mainly with rainfall. Males called from the edge of temporary or permanent ponds, began vocalization activity at dusk, and finished around 2300 or 2400h. During the peak of the vocalization period (Dec- Jan), calling activity could extend up to 0400 or 0500h. Three types of vocalizations associated with reproduction were recorded: advertisement call, territorial call, and courtship call. The advertisement call was the most common vocalization. Males and females showed no sexual dimorphism in SVL. However, the males of one population were significantly larger than those of the other population studied. This fact could be explained by frog-hunting in one of the areas, which could wipe out the larger males of the population. Foam nests were recorded mainly in Oct-Nov 2001/2002 in depressions at the edge of temporary ponds, always protected by vegetation. A mean of 6.5% of the eggs present in the foam were fertilized and the other 93.5% possibly are used as a food source by the tadpoles. Mean diameter of the foam nest was 25.4 cm and mean height was 11.4 cm.

Sexual selection and signal detection theories predict that females should be selective in their responses to mating signals in mate choice, while the response of males to signals in male competition should be less selective. The neural processes underlying this behavioural sex difference remain obscure. Differences in behavioural selectivity could result from differences in how sensitive sensory systems are to mating signals, distinct thresholds in motor areas regulating behaviour, or sex differences in selectivity at a gateway relaying sensory information to motor systems. We tested these hypotheses in frogs using the expression of egr-1 to quantify the neural responses of each sex to mating signals. We found that egr-1 expression in a midbrain auditory region was elevated in males in response to both conspecific and heterospecific calls, whereas in females, egr-1 induction occurred only in response to conspecific signals. This differential neural selectivity mirrored the sex differences in behavioural responsiveness to these stimuli. By contrast, egr-1 expression in lower brainstem auditory centres was not different in males and females. Our results support a model in which sex differences in behavioural selectivity arise from sex differences in the neural selectivity in midbrain areas relaying sensory information to the forebrain.

Ideas about the ontogenesis of the nominative subspecies of the Sandhill Crane are limited to two student publications (Boice, 1977; Reed, 1988). Our observations were carried out on 5.06-17.08.1991 in the vicinities of the Ust’-Chaun (= Rytkuchi) Village (68°54`N, 170°43`E) at the southeastern extremity of the Chaun Bay (North-Western Chukotka, Chaun District of Chukotka Autonomous Okrug, Russia) on the 7×9 km area between the southeastern shoreline of the Chaun Bay in the North-West and the Palyavaam River in the South (Winter, 2002, 2005). At an elevation of 30-50 m from the nest, an 80-cm bar with a wide ribbon and a double-sided number was set vertically. The nestlings were marked with multi-coloured fabric strips on one or on both tibiae, weighed on a lever pharmacy scale and measured with a vernier caliper.32 measurements and descriptions of 16 chicks from 10 families were carried out from hatching to their 44th day of life. During the incubation period, on June 6-27, 27 crane pairs were visited 44 times, chronometring their behaviour for 32 hours. After hatching, on June 21 – August 17, 23 pairs were visited 94 times, and their behavior was chronometred for 48.4 hours. Changes in the colour of featherless body parts during ontogenesis are described. As well as the Eurasian, White-Naped and Demoiselle Cranes, the tip of the lower mandible in the Sandhill downy chicks is split at hatching and during the first two days; by the end of the 3rd day the distal part of the left and the right mandibles coalesce together forming a smooth dorsal edge. Regressions of three indicators of beak growth are later represented by the second-order polynomials. The rudimentary claws on the wing (Phalanx digiti alulae – 1st toe) and the end of the wing (Phalanx digiti majoris – 2nd toe) remained almost unchanged for 3 weeks, and by the 44th day (24-fold increase in body weight!) they increased by 1.4-2.0 times. The growth of the metatarsus, toes and their claws is represented by the second-order polynomials. In the individual variability of the Sandhill Crane downy chicks, the unusual shape of their head is clearly visible. In 75% of the observations, it was similar to the gladiator’s head in a helmet: the short lustrous smooth down that forms a kind of slightly convex glasses around eyes, sharply contrasting with the considerably longer down on the vertex and occiput, forming a rounded crest (similar to that in the Jay, Garrulus glandarius) which begins with a ledge on the occiput. Probably, the embryonic down (praepennae) in some of the Sandhill Crane chicks grows longer than the first 2-4 days of life than in the White-Naped Crane (Ilyashenko, 2005). No areas of down contrasting in colour with the rest of the head and ‘face’ were found in the nestlings of other above-mentioned cranes. The Sandhill Crane downy chicks have contrasting grayish brown spots on the light yellow, ‘golden’ background of the lower part of the frons over the beak base (upper edge of the eye-stripe) as well as crescent-shaped spots in front and above, behind and below the eyes. Another unusual feature of the Sandhill Crane downy chicks is the presence of the egg «tooth» not only on the upper mandible (44.4%), but also on the lower mandible (55.6% of the chicks). In two chicks from one nest aged 2 and 3 days, two rows (in one chick incomplete) of light grey embryonic fluff proximally and distally on the “heel” (intertarsal joint) were found. This fluff was completely worn within a week. This sort of the apteria has not been described in the monograph on chickpterilography of the 10 bird orders of the world fauna yet (Ilyashenko, 2015). The visible on the abdomen outer part of the oval yolk sac (Saccus vitellinus), oriented by the long axis along the chick body, as well as the suture of the sphincter that closed it, are surrounded with the apterium of the yolk sac (we called it Apterium vitellinum;Winter, Gorlov, 2019), which is a diamond-shaped structure with rounded angles and is not yet known for the cranes. In the first 3 days of life, the yolk sac degraded quickly, but its size depended not only on age, judging by its size variation in three-day-old chicks. Apparently, its size depended much on the food availability in the nest surroundings. Chicks picked berries on their own from 13-14 hours old and, probably, their abundance or scarcity can be explained by such an uneven loss of the initial size of the yolk sack. This observation contradicts the “golden rule” for the Demoiselle and Eurasian Crane downy chicks, in which in the first days of chicks life, the younger one was heavier and had a larger yolk sac (Winter et al., 1999; Winter, 2008; Winter, Gorlov, 2019). During the two-hour observations of 3 crane families on the 14-18th days of the chick life, we did not record the food passing “from beak to beak”. Unlike the first week of life, the adult birds only pointed with their beaks to the food the chicks should peck. Comparison of the behavior of 5 crane species near the clutches and chicks showed that the Sandhill Crane behaved abnormally, since the distance between the observer and the adults displaying their anxiety at the nest ranged from 15 to 40 m! At the same time, there were no sexual differences in the adults behavior near the nest. The half-squat pose with half-open and roof-shaped wings, raised above the back, with the body (neck-tail) at an angle of 30-35 degrees to the ground, is very similar in the Sandhill, Hooded and Eurasian cranes, while the Demoiselle Crane had different distraction poses. Flying around the observer by adult birds at the height of 30-60 m near the nest or chicks is observed in all crane species that we know, but in the Sandhill Crane this action is obviously socialized. As the unprecedentedly high for cranes nesting density in 1991 was 0.74 nest per 1km2 and the average distance between the nests was1082.1 ± 62.6 m (Winter, 2002), the pair's anxiety near the nest had a clear social impact and probably decreased the number of the destroyed neighbours’ nests. A disturbed pair of birds, with screams in flight, followed the observer until he reached the boundary of the neighbouring nesting area. Then the neighbouring pair also left its nest and flew around the observer. If he had not followed that pair before, the search for their nest was often unsuccessful. Marking nests and nestlings has enabled estimation of the distance of the crane families from their nests in 56 observations from hatching to being capable of flight. The distance was significantly different (ß>0.95) only between the chicks from hatching to 10 day old and those of 11-20 day old. The maximum distance of the family from its nest was 1000-1100 m and was probably determined by the fact that by the time of hatching the non-breeding territorial pairs (making nests but having no clutches in them) and the pairs whose clutches died had already left their nesting sites.

AbstractThe courtship behaviour of pygmy newts, Triturus pygmaeus, consists of three phases: orientation, static display (often not clearly differentiated from each other) and spermatophore transfer. The repertoire of male sexual behaviour consists of nine different movements. Exhibition, an alert posture in which the male advances with small jumps around the female, is the most frequent behaviour. The predominant tail movement is slow fan, in which the tail is softly undulated from approximately 30° to 140°. In contrast to the tail lashes of the large Triturus species, the tail only occasionally beats against the male's flank and never touches the female. Bait mimic tail movements (described for T. boscai as flamenco) are used to attract the female's attention. The duration of sexual encounters was 2203 s on average, in which males displayed in about 81% of this time. Although the courtship of T. pygmaeus shows clear differences from that of its closest relative, T. marmoratus, it should nevertheless be grouped with the larger Triturus species: conspicuous tail movementes are used to attract the attention of the female, but no direct response is required of her to complete the courtship. En el cortejo de los tritones enanos, Triturus pygmaeus, se pueden distinguir tres fases diferentes: fase de orientación, fase de exhibición estática y fase de deposición del espermatóforo. Las dos primeras no se distinguen claramente, sino que frecuentemente se alternan entre sí. Los machos de esta especie realizan nueve pautas diferentes relacionadas con el comportamiento sexual. Entre ellas, destaca la que denominamos exhibición , en la que el macho, en una posición de alerta con todo su cuerpo muy estirado, realiza pequeños saltos alrededor de la hembra. Este comportamiento, que es el que se observa con mayor frecuencia, parece tener un papel importante como señal visual en el cortejo. Otra pauta importante por su frecuencia es la denominada abanico lento, en la que los machos ondulan lentamente su cola, a la vez que abren y cierran el ángulo (que oscila entre 30° y 140°) que ésta forma con su cuerpo. Otra pauta característica es el latigazo corto, un movimiento brusco de la cola similar al de otras especies de tritones, de las que se diferencia porque la cola sólo ocasionalmente alcanza a golpearse contra su propio cuerpo y nunca llega a tocar a la hembra. Se describe en esta especie una pauta de engaño, flamenco, en la que los movimientos de la cola imitan a los de supuestas presas con el fin de atraer rápidamente la atención de la hembra. Esta pauta había sido descrita anteriormente para T. boscai. La duración media de los cortejos fue de 2203 s, en los que el 81% de este tiempo los machos elaboran pautas de cortejo. Aunque el cortejo de T. pygmaeus muestra claras diferencias con la especie próxima, T. marmoratus, se considera que debe ser clasificado en el mismo grupo, entre los tritones de mayor tamaño, en las que el cortejo se caracteriza por el uso de comportamientos muy conspícuos para la atracción de la hembra, y en el que no se requiere un respuesta directa de la hembra para realizar la deposición del espermatóforo.