Search

Summary While animals navigating the real world face a barrage of complex sensory input, their brains have evolved to perceptually compress multidimensional information by selectively extracting the features relevant for survival. For instance, communication signals supporting social interactions in several mammalian species consist of acoustically complex sequences of vocalizations, however little is known about what information listeners extract from such time-varying sensory streams. Here, we utilize female mice’s natural behavioural response to male courtship songs to evaluate the relevant acoustic dimensions used in their social decisions. We found that females were highly sensitive to disruptions of song temporal regularity, and preferentially approached playbacks of intact male songs over rhythmically irregular versions of the songs. In contrast, female behaviour was invariant to manipulations affecting the songs’ sequential organization, or the spectrotemporal structure of individual syllables. The results reveal temporal regularity as a key acoustic cue extracted by mammalian listeners from complex vocal sequences during goal-directed social behaviour. Highlights - Natural behaviour is used to probe how mouse listeners encode vocal sequences - Listeners are highly sensitive to disruptions of the songs’ rhythmic regularity - Female behaviour is invariant to changes in song sequence - Approach behaviour is robust to the removal of syllable spectrotemporal dynamics

Biologists have long been fascinated by the elaborate courtship displays performed by diverse organisms throughout the animal kingdom. The evolution of courtship behaviour often requires specializations of neural, sensory and motor systems. In addition, physically impressive displays may also require optimized metabolic, respiratory and cardiovascular systems to sustain the neuromuscular demands. Hormonal signalling can reach all of these tissues simultaneously to prepare them for use in courtship. Studies of male golden-collared manakins, Manacus vitellinus, a small bird of the Neotropics with a physically intense and noisy courtship display, have uncovered numerous androgen-dependent neuromuscular and metabolic specializations that enable not only the performance of elaborate courtship routines, but also their evolutionary exaggeration. However, physiological specializations for one function can create limits on their use for other purposes. Such trade-offs may influence the way courtship develops but may also provide information used by females for mate choice. We review this body of work with an eye towards expanding our appreciation of the evolution of widespread tissue hormone sensitivity and hormone action as the system through which elaborate courtship behaviours evolve.

Incorporating microsatellite techniques to determine parentage is a powerful addition to behavioral mating system studies in wild animals. Nonetheless, in some tetrapod taxa such as lizards, there are relatively few direct comparisons of individual reproductive success measured genetically versus estimates based on behavioral interactions, especially in species where males and females do not maintain prolonged social contact. We combined observations of behavior with microsatellite analysis of parentage over ten seasons in male Collared Lizards, (Crotaphytus collaris), to test the extent to which the proportion of each female’s total courtship interactions with different males predicted the proportion of total offspring sired by those males (proportion of paternity). Territorial males (T-males) court females frequently. Non-territorial (NT) males on the other hand behave stealthily. This allows them to court females, albeit less frequently, while limiting attacks by T-males. Both T- and NT-males occupied habitats that varied in structural complexity which might influence which males court and sire offspring with individual females, therefore we included habitat type (simple vs. complex) and male social tactic as possible predictors in our test. Proportion of courtship by NT-males did not predict their proportion of paternity in either habitat type. Courtship by T-males was a strong predictor of paternity in simple habitats but not complex habitats. Our findings support the hypothesis that courtship is a more accurate predictor of T-male mating success in simple habitats, which is consistent with previous findings suggesting that reduced area and topographical heterogeneity, especially the absence of subsurface crevices in simpler habitats, makes it more economical for T-males to prevent surreptitious mating by NT-males. Our study, therefore, highlights the importance of considering possible effects of alternative social tactics and variation in environmental conditions when testing the accuracy of behaviorally based estimates of breeding relationships, especially in polygamous species with multiple paternity.

Sexual signal evolution is shaped by whether only one or both sexes execute mate choice. When mate choice by both sexes is considered, the same signalling modality is generally inferred for males and females. In the noctuid moth Chloridea (Heliothis) virescens (Lepidoptera: Noctuidae), both sexes may be signallers and responders, as both emit a sex-specific pheromone. Male mate choice is based on the female sex pheromone, perceived via the antennae, and has been well documented. However, whether females choose partners and whether their choice is based on the male pheromone are unknown. Since female mate choice is expected when males vary in quality, we reared males on two different larval diets that affected their size, which correlated positively with their fitness. When given a choice, more females mated with larger than with smaller males, and these females produced more eggs and larvae. Female choice was not affected by the absolute amount or composition of the male pheromone. Moreover, we found that antennaless females mated as readily as intact females, indicating that antennal sensory input is not required for females to mate. To determine whether females make an active choice, we studied courtship behaviour in detail and observed that females determined the outcome of courtship by moving away from the male (avoidance) or by facilitating copulation with an abdominal bend (acceptance). Additionally, we discovered that tactile sensory stimuli may be involved during courtship. Because tactile interactions may mediate contact-based (chemical) communication, we also investigated putative pheromone components on moth legs, but found no differences between the sexes. Together, our study is the first comprehensive investigation of female mate choice in a heliothine moth.

Alternative reproductive tactics (ARTs) often exhibit more than one mating behavior depending on social context (i.e., behavioral plasticity). It has been hypothesized that by constraining an ART from reaching optimal morphological states, intralocus tactical conflict could promote the maintenance of behavioral plasticity in ARTs, rather than the use of a fixed mating behavior to match an optimal morphological state. For selection on either behavior or morphology to influence one another, there would need to be genetic integration between these traits within the behaviorally plastic males. To examine this possibility, we compared the relationship between body shape, body size and propensity to use sneak-chase behavior across experienced wild-caught males and inexperienced lab reared males from the behaviorally plastic ART (sneaker males) of the swordtail fish Xiphophorus multilineatus. The smaller, more narrow-bodied sneaker males use both force copulatory sneak-chases and courtship behavior to access females, while the larger, deeper-bodied courter males are fixed in their use of courtship behavior. We detected similar relationships between body size and the propensity to use sneak-chase behavior within the sneaker males when they were alone with a female (no competitor present) for both experienced and inexperienced males, suggesting genetic integration between behavior and body size. Body shape, on the other hand, was more complex and suggested both genetic integration (more fusiform males from both groups were more likely to use sneak-chase), as well as learning depending on subtle differences in body shape. We discuss how intralocus tactical conflict on morphological traits that are genetically integrated with behaviors has the potential to maintain behavioral plasticity in the X. multilineatus sneaker males and influence the evolution of ARTs in general.

The Brazilian basslet (Gramma brasiliensis) is an ornamental fish species of significance to the fish market, and the development of a breeding protocol is of interest to the aquarium trade. There is little information regarding the behaviour of G. brasiliensis in captivity; thus, the aims of this study were to: (1) investigate pair and harem formation in different-sized aquaria (70 and 110 L) and tanks (150 and 310 L); (2) investigate the choice of different macroalgae species and synthetic materials by the fish for nest building in captivity; and (3) describe the courtship behaviour of captive fish and compare it with available literature for G. brasiliensis and Gramma loreto in natural environments. Based on the results, we suggest that G. brasiliensis should be kept in pairs because of their aggressive behaviour. Macroalgae of the genus Chaetomorpha and all synthetic materials were used by the fish to build nests. The courtship behaviour of G. brasiliensis in captivity is described for the first time and is similar to that reported for G. loreto in a natural habitat, namely ‘U-turn with body quivering’.

Reproductive behaviour is often targeted by behavioural parasitism due to its high energy costs and direct relationship with fitness. Courtship behaviour represents a substantial amount of the investment in reproduction, as it usually requires conspicuous movements that are energetically demanding and increase predation risk. Here, we present an alternative reproductive tactic in which dominant male sailfin tetra, Crenuchus spilurus Gunther 1863, parasitize the courtship behaviour of subordinate males. By conducting field observations and controlled experiments in laboratory, we show that, under low availability of nesting sites, dominant males favour a close-range defence of nesting sites, while subordinate males invest more in courtship activities. However, subordinate males often directed courtship movements towards a nesting site dominated by a concealed dominant male, who subsequently took over the female and resumed courtship. Our laboratory experiment also showed that only dominant males obtained spawning success regardless of the amount of effort allocated to courtship behaviour, circumventing the initial female preference for the subordinate male. Subordinate males were more likely to initiate contests and ceased courtship upon losing aggressive contests. In such instances, the courtship effort of dominant males was higher, suggesting that dominant males modulate their courtship effort according to the effort of subordinate males. We refer to this tactic as courtship piracy. For being dependent on resource defence, the effectiveness of courtship piracy is contingent on the defendability of nesting sites. In a follow-up experiment, we show that dominant males invest more in nesting site defence only when nesting sites are scarce. Since rainfall controls the amount of nesting sites in the natural habitat, we suggest that seasonality modulates the relative contribution of courtship piracy and female mate choice to reproductive success.

Across animal taxa, individuals eavesdrop upon courting conspecific males, often in an attempt to steal mating opportunities. While multimodal signals can increase the likelihood that choosers respond to courters, such multimodal signals might also attract the unwanted attention of conspecific eavesdroppers. Previous studies of the brush-legged wolf spider, Schizocosa ocreata, demonstrate that field-experienced males court in response to visual displays of conspecific male courtship more than do laboratory-raised males. Furthermore, other studies demonstrate that males can learn to associate visual signals with the presence of a nearby female. Male S. ocreata, however, use a combination of vibratory and visual signals in their multimodal courtship display. Whether such associative learning varies based on which signal modality is experienced or whether multimodal signals result in enhanced learning remains unknown. Consequently, we examined eavesdropping on courtship behaviours of S. ocreata, with added emphasis on learning to respond to unimodal versus multimodal playback. We used vibratory and video playback techniques to test whether associative learning results in varied courtship levels when males associate unimodal or multimodal courtship signals with the presence of a nearby female. Results show that male S. ocreata associated courtship playback with the presence of a nearby female (i.e. courted at higher levels), regardless of whether courtship playback was unimodal or multimodal, demonstrating that male S. ocreata are capable of learning in multiple modalities. Multimodal playback, however, did not appear to enhance males’ ability to associate conspecific courtship signals with female cues. Courtship behaviours were greater in response to vibratory playback, though, suggesting that male S. ocreata weight modalities differently than females do. We further discuss the implications of this result regarding the communication network of S. ocreata.

Reproductive behaviour is generally under strong natural and sexual selection, meaning that variation in mate attraction investment reveals important fitness trade-offs. Nevertheless, in many taxa with sex-specific displays, individuals differ considerably in such investment. Male white-ruffed manakins, Corapipo altera (Pipridae), exhibit dramatic variation in display investment, despite having a mating system shaped by strong sexual selection. We tested three alternative hypotheses that could explain this variation: (1) individual quality and condition, (2) competition or (3) cooperation. We manipulated the social environment of male manakins at display sites in two experiments. First, we increased the acoustic signalling around focal males’ display sites by broadcasting the sounds of other displaying males to simulate elevated display of neighbouring males. Second, we temporarily prevented neighbouring males from using their display sites, thereby increasing the competition at focal display sites. Males reduced rates of vocalization in response to elevated acoustic signalling, suggesting that males may cooperate with neighbours to advertise the locations of leks, minimizing their individual effort when possible. The number of individuals at the focal display site and the number of silent displays increased when neighbours were prevented from displaying nearby, consistent with the competition hypothesis. However, the constancy in time investment and rates of other display behaviours throughout both manipulations suggests that male quality or condition underlies much of the individual variation in behaviour at display sites. Overall, our results are consistent with cooperation and individual quality mediating individual investment in display site advertisement. While manipulations created opportunities for competition, the responses of focal males were not consistent with antagonist social interactions affecting investment in display. This work demonstrates the importance of both intrinsic and social drivers shaping investment in courtship behaviour and highlights the potential for multimodal displays to facilitate cooperation.

Pair formation in ducks is thought to be influenced by the acquisition of breeding plumage, the occurrence of courtship display, or both. We examined the frequency of pair formation in Mallard (Anas platyrhynchos), Green-winged Teal (Anas crecca carolinensis), and Northern Shoveler (Spatula clypeata) in the central valley of California in relation to the frequencies of male attainment of breeding plumage and courtship display. Predictions related to two hypotheses are: (1) the timing of pair formation is directly related to the attainment of breeding (definitive alternate) plumage by males, and (2) frequencies of courtship display are highest during pair formation. Most female Mallard were paired by the end of October, with >80% in pairs by early December. Of Northern Shoveler, 90% were paired by early January and 90% of female Green-winged Teal were paired by early February. The highest rates of courtship display by Mallard were observed during October through November, by Northern Shoveler in November, and by Green-winged Teal in November through January. Courtship display was, therefore, relatively frequent at the same time as pair formation for all three species. Northern Shoveler spent less time in courtship display than the other two species. Most (90%) male Mallard had acquired alternate plumage by mid-November, Northern Shoveler by early February, and Green-winged Teal by mid-December. Thus, timing of pair formation coincided with timing of attainment of breeding plumage in Mallard and Green-winged Teal but not Northern Shoveler.

The Northern chamois (Rupicapra rupicapra) is a weakly polygynous species widely distributed in the mountain regions of Europe and the Near East. The Balkan chamois (R. r. balcanica) occurs in the mountain regions of southeastern Europe, and its ecology and behavior during the rut are largely unknown, making it one of the most understudied subspecies of chamois. Despite the scarce body mass dimorphism, males display a developed behavioral polymorphism that affects the mating success and possibly survival. Here, we provide the first quantitative analysis of the behavioral repertoire and activity budget of rutting male Balkan chamois and compare frequencies of different behavioral categories (i.e., courtship and direct and indirect aggression) with those observed in Alpine (R. r. rupicapra) and Tatra (R. r. tatrica) chamois. Male Balkan chamois have a rich behavioral repertoire (24 different behavioral patterns) with a prevalence of courtship behaviors and a higher frequency of indirect than direct forms of aggression. Compared with Alpine and Tatra chamois, no significant difference in the frequency of different behavioral categories was detected. The activity budget showed that when not rutting, males spent ~ 41% of their time foraging and ~ 59% lying down. Time spent rutting was negatively correlated with time spent foraging and time spent lying down, suggesting that time spent for mating activities increased at the expense of foraging and resting. In dominant males, the frequency of courtship behavior was higher than the frequency of aggressive behaviors, whereas in subordinate males, no differences were detected among behavioral patterns. Furthermore, no significant differences in activity budgets were detected between male types. This is the first report of Balkan chamois rutting behavior and provides important insights into the ecology of a poorly known subspecies.

Although reproductive behavior is of general interest in evolutionary studies, ecology, and conservation of biodiversity, there are relatively few records on courtship behavior for several animal groups, which include birds, one of the most well-studied vertebrates. Herein we report novel information on a poorly known Neotropical owl species, by reporting courtship displays of the Black-banded Owl (Strix huhula), registered in the Brazilian western Amazon. We describe two events of courtship exhibited by a pair of S. huhula, including vocalization patterns, body movements, and courtship feeding, which suggests that this species possess complex social behavior. Our study provides pivotal information to the understanding of the reproductive biology of the Black-banded Owl and others owl species with similar patterns of reproduction and courtship behavior.

For drug resistance patients, removal of a portion of the brain as a cause of epileptic seizures is a surgical remedy. However, before surgery, the detailed analysis of the epilepsy localization area is an essential and logical step. The Electroencephalogram (EEG) signals from these areas are distinct and are referred to as focal, while the EEG signals from other normal areas are known as nonfocal. The visual inspection of multiple channels for detecting the focal EEG signal is time-consuming and prone to human error. To address this challenge, we propose a novel method based on differential operator and Tunable Q-factor wavelet transform (TQWT) to distinguish the focal and nonfocal signals. For this purpose, first, the EEG signal was differenced and then decomposed by TQWT. Second, several entropy-based features were derived from the TQWT subbands. Third, the efficacy of the six binary feature selection algorithms, binary bat algorithm (BBA), binary differential evolution (BDE) algorithm, firefly algorithm (FA), genetic algorithm (GA), grey wolf optimization (GWO), and particle swarm optimization (PSO), was evaluated. In the end, the selected features were fed to several machine learning and neural network classifiers. We observed that the PSO with neural networks provides an effective solution for the application of focal EEG signal detection. The proposed framework resulted in an average classification accuracy of 97.68%, a sensitivity of 97.26%, and a specificity of 98.11% in a tenfold cross-validation strategy, which is higher than the state of the art used in the public Bern-Barcelona EEG database.

We investigated the significance of sexual maturity, courtship behaviour and mating refusals in an aphidophagous ladybird, Coccinella transversalis Fabricius using four mating combinations, viz. virgin couple, previously mated couple, virgin male x mated female, and mated male x virgin female. Adult females and males attained sexual maturity at a very early age of 3.47 ± 0.32 and 4.02 ± 0.75 days after emergence respectively revealing slight protogyny. Early sexual maturity trait enables early initiation of sexual activities leading to increase in its population dynamics. The male courtship displays were prominent in virgins than in the non-virgins, which indicate that males perhaps resort to courtship when they are mating for the first time. The duration of copula (24.70 ± 4.50 min) and the number of bouts (343.60 ± 56.53) were greater in the copulation of non-virgins than that of the virgins (17.19 ± 5.19 min of copulation with 265.90 ± 79.73 bouts). The female mating refusals were higher in mated females than in virgins suggesting that females resist to re-mate due to probable sufficiency of single mating for their progeny. Both early sexual maturity and increased incidences of mating refusals by the mated females seemingly are traits that favour sexual selection. Attainment of early sexual maturity and offspring production might help mass-rearing of C. transversalis for the aphid biocontrol programme.

Thomas Hardwicke's acquisition of drawings of the lesser bird of paradise ( Paradisaea minor) and the subsequent publication of his painting of the male bird performing its elaborate courtship ritual in J. E. Gray's Illustrations of Indian zoology are described.

Previous research on non-verbal courtship behavior (flirting) has been conducted almost exclusively with heterosexual participants and has relied upon an evolutionary-based, reproduction driven framework. This study extended beyond a reductionist perspective to examine the differential contributions of gender identity, traditional masculinity-femininity, gender role ideology, and sexual orientation in predicting flirting behavior. Results from 626 participants revealed that, across all participants, gender, masculinity-femininity, and gender role ideology were predictive of flirting techniques, while sexual orientation was not. Among self-identified men only, sexual orientation was predictive, until the introduction of masculinity-femininity into the model nullified the effect. Among self-identified women, only masculinity-femininity and gender role ideology predicted flirting behavior. The negligible predictive role of sexual orientation suggests that existing paradigms of flirting research may be adequate to capture experiences of flirtatious behavior among sexual minority individuals.

Insects are exposed to cadmium stress since cadmium pollution has increasingly become a serious global environmental issue. However, until now few studies have paid attention to the effect of heavy metals on insect reproductive behaviors. In our study, the courtship behaviors, mating behaviors and fecundity of beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae) exposed to different concentrations of cadmium in artificial diets at larval stage were studied. The results showed that cadmium stress changed the courtship rhythm by significantly advancing or delaying the courtship starting time. Low dose of cadmium (0.2 mg/kg) increased the courtship frequency in the first two scotophases, but in the fourth phase, the two cadmium treatments reduced the frequency. The total courtship duration was significantly shortened in the first six scotophases except high dose of cadmium treatment (51.2 mg/kg) in the sixth dark phase. Paired adults did not mate after the seventh scotophase under low cadmium exposure, while high cadmium stress made the paired adults just copulate in the first four scotophases. The daily mating rate and total mating rate decreased with the increase in cadmium concentration. The number of eggs of low cadmium treatment was higher than that of control, but the difference was not significant; the number of eggs in high cadmium treatment was lower than that of control and low cadmium treatment. Our results indicate that cadmium exposure can disrupt the courtship rhythm for females and has negative influences on copulation behavior and high cadmium stress can reduce fecundity. Hence, the insect population increase will be affected by heavy metal pollution. Our study will provide scientific reference for environmental risk assessment of heavy metal pollution.

Drosophila melanogaster males reduce courtship behaviour after mating failure. In the lab, such conditioned courtship suppression, aka 'courtship conditioning', serves as a complex learning and memory assay. Interestingly, variations in the courtship conditioning assay can establish different types of memory. Here, we review research investigating the underlying cellular and molecular mechanisms that allow male flies to form memories of previous mating failures.

Many species of insects have sex-specific and species-specific cuticular lipid profiles that help regulate mate recognition and courtship behaviour. However, in adult butterflies, little is known about cuticular hydrocarbons (CHCs), the main component of the lipid profile, and their function in mating. Here, we investigated whether Papilio polytes males use cuticular lipids and major CHCs in mate discrimination. When males were presented with freshly killed female and male specimens, copulation attempts were more frequent after contact with the females. Upon removal of the cuticular lipid with solvent washes, the ratios of copulation attempts were similar for both male and female specimens. When male or female cuticular lipid extracts of P. polytes or Papilio protenor (a sympatric and related species) were applied to washed female specimens, males displayed less interest in specimens treated with extracts other than that of the conspecific females. Chemical analysis of the extracts revealed that the CHC profiles, especially the C23–C25 range, differed greatly between the sexes of the two species. Of the identified major hydrocarbons, authentic chemicals 7-tricosene (characteristic of P. polytes males) and 9-pentacosene (characteristic of P. protenor females) greatly reduced the ratio of male copulation attempts with the treated female models. Hence, P. polytes males use the CHC profile of their partner for mate discrimination, and particular alkenes probably play important roles in the prevention of interspecific and same-sex courtships.

Bristle patches on the carapace behind the eyes were found for the first time in both males and females of the four species of mud crab Scylla spp. Electrocardiography revealed that the bristle patches of Scylla paramamosain were sensitive to touch (with a glass capillary) but not to chemical stimulation (with sugarcane juice). To elucidate the function of these touch signals, the courtship behaviour of S. paramamosain was video-recorded in a broodstock tank. A male approached a female, extended a walking leg over her carapace, touched her bristle patches with a dactyl, mounted her, and probed the bristle patches further with the third maxillipeds. Touch stimulus may be a signal for courtship in Scylla and one of the chain stimuli for the completion of mating behaviour.

In fish, social interactions are commonly accompanied by acoustic signalling. Males have been found to produce sounds in a large range of species, but female sounds have received considerably less attention. But even in males, there remain significant taxonomical gaps, e.g. in one of the largest fish families, the wrasses. Here, we investigate sound production in territorial males and females of the corkwing wrasse in a field study in Norway. We complemented an in-depth analysis of the visual and acoustic behavioural repertoire of territorial males by descriptions of female behaviours. Males as well as females produced sounds in courtship and agonistic contexts. We recorded four types of sounds and found significant differences between male and female sound properties. We hereby provide one of the first descriptions of sound production in wrasses and, to our knowledge, the first one to also investigate female sound production. Our study shows that wrasses are an underappreciated family when it comes to sound production. With a repertoire of four different calls, corkwing wrasses are remarkably versatile among fishes. Our results highlight the potential and importance of future research about sound communication in neglected taxa, and in both sexes.

Behavioural thermoregulation can ameliorate thermal stress but is costly. For species that court in a thermally stressful microhabitat, sexual selection via endurance rivalry favours individuals that are able and willing to endure harsh conditions in the courtship habitat, as retreats to a thermal refuge will reduce mating opportunities. The relative costs and benefits of refuge use versus continued courtship in the face of thermal risk, which vary across abiotic and biotic contexts, determine the optimal behavioural strategy. We examined the social and abiotic factors driving behavioural decisions related to thermoregulatory retreat in the fiddler crab Austruca mjoebergi. Male fiddler crabs perform a courtship display on the thermally stressful intertidal sediment surface. Time on the surface, and thus time available for display, was limited by high temperatures; as temperature increased, surface time decreased. Yet when presented with a stimulus female, males were more likely to perform the courtship display, displayed at a higher rate and increased time spent on the surface. These results demonstrate that behavioural decisions related to thermal retreat depend both on the abiotic conditions that influence the degree of thermal stress and on the social conditions that influence the reproductive prospects of the individual.

A new species of Alavesia (Empidoidea: Atelestidae), Alavesia wimpala sp. nov. is described from the mid-Cretaceous amber of Myanmar. Together with the recently described Alavesia longistylata H. Zhang & Wang in Zhang et al. 2020 and A. longicornuta Sinclair & Grimaldi, 2020 the herein described species Alavesia wimpala sp. nov. forms a distinct group of Alavesia Waters & Arillo, 1999 which we consider deserving a subgeneric level. Subgenus Pennonalavesia subgen. nov. is introduced here comprising three species. Males of these species have a very prolonged third segment of stylus bearing a long-oval pennon. The palpus is prolonged and blade- or ribbon-shaped. A catalogue to all 19 species of the genus is given as well as a key to Alavesia (Pennonalavesia subgen. nov.). The function of the prolonged antenna in display and courtship is discussed. Most probably the triangular shape of the wings with its broad base allows a hovering flight in these species to present the pennons at the end of stylus. These characters indicate a high derived courtship behaviour in these flies in the Cretaceous period. On the other hand a possible raptorial behaviour of the new species is suggested.

Multiple paternity behavior (MP) has been recorded for seven elasmobranch orders. It remains unclear how this common behavior evolved and whether it occurs in all elasmobranchs or in certain lineages. Although MP may provide genetic benefits, elasmobranchs display an aggressive courtship behavior and females may become severely wounded, making multiple mating costly. Females can perform multiple matings to avoid excessive harassment in males (polyandry by convenience hypothesis). Studies challenge this hypothesis, suggesting that females are often able to avoid mating attempts by inappropriate males and copulate with several potential. In this study, an scientiometric analysis was performed concerning elasmobranch species presenting MP records, to reconstruct the evolutionary history of the complex sexual behavior in this group. The results indicate that MP behavior is widespread in the subclass, suggesting that it may have been originated in the common ancestor of elasmobranchs (plesiomorphic state). The data indicate a knowledge gap regarding the detection of MP in other elasmobranch orders and we suggest that investigative studies on the neglected elasmobranch and chimaera orders are required.

Within populations, individual males adopt different courtship tactics due to differences in their competitive ability, which may vary depending on the animal’s age and size. To test the hypothesis that mule deer (Odocoileus hemionus) and white-tailed deer (O. virginianus) males vary their courtship behavior based on their size, we conducted focal observations of 144 mule deer and 85 white-tailed males that varied in size, at a large grassland site in southern Alberta. The smallest mule deer males devoted more time to feeding, were less likely to engage in late-stage courtship than larger males and were less likely to move among female groups. Other males, including small white-tailed males, appeared to use a roving strategy to search for estrous females in different groups, which is consistent with recent research on male movements. Both medium and large males increased the time they spent in one-male groups, and specifically isolated pairs, as courtship advanced, presumably to reduce competition with other males. However, this trend was most pronounced for medium mule deer males, and for all size classes of white-tailed deer. In contrast, large mule deer males spent a similar proportion of time tending females in all group types. Our results identified potential size-dependent tactics for mule deer males. In contrast, white-tailed males of all sizes appeared to rely on a tactic of finding and tending estrous females in isolation from other males.

Although male courtship displays have evolved primarily to sexually attract females, they also generate inadvertent public information that potentially reveals the courter’s relative sexual attractiveness and the perceived quality and sexual receptivity of the female being courted to nearby eavesdropping male competitors, who in turn may use this information to bias their social partner choices. We tested this hypothesis by first presenting individual eavesdropping male guppies (Poecilia reticulata) the opportunity to simultaneously observe two demonstrator males whose courtship behaviour was manipulated experimentally to differ, following which we tested them for their preference to associate socially with either demonstrator males. Test males preferentially associated with the demonstrator male who they had previously observed courting a female over the other (non-courting) demonstrator. This social association preference was not expressed in the absence of a female to court. Our findings highlight the potential for sexual behaviour influencing male-male social associations in nature.

Urbanization rapidly alters the environment, often leading to decreased biodiversity. One abiotic selection pressure uniquely associated with urbanization is the urban heat island (UHI) effect—wherein built structures (e.g. paved surfaces) capture heat during the day, retain it through the dark cycle and result in significantly elevated night-time temperatures. Relatively few studies have asked what effects the UHI might have on the development and behaviour of urban animals, and even fewer have asked this question of urban arthropod pests who rely on external heat sources and can experience explosive urban population growth rates. In particular, behavioural plasticity is often cited as a critical phenotype for organisms to thrive after rapid environmental change such as urbanization. Here, the relationship between elevated urban temperatures and behaviour was examined in the western black widow spider, Latrodectus hesperus. With regard to the UHI, young spiderlings raised at urban, elevated temperatures showed significantly reduced life span, reduced body mass, elevated web building, heightened voracity towards heterospecific prey and sibling cannibalism. In contrast, males studied later in the final prereproductive moults and raised at urban, elevated temperatures showed reduced life span, decreased adult body condition and increased voracity towards prey. We found no effects of temperature on late-stage male web building or courtship behaviour. UHI temperatures simulated in the laboratory present black widow spiders with a myriad of developmental problems, but our data suggest these spiders use temperature-sensitive behavioural plasticity to attempt to accommodate this stressor.

Sexual signals are often elaborate, even spectacular, behaviours. The reproductive rewards for successful display are great, but so are the potential costs. These costs include not only the resources needed to produce a display, but also resources required if the display evokes attack from a rival or predator. To maximize payoff, individuals must monitor both internal and external cues to adjust display effort. We know surprisingly little about how these competing demands are balanced. Leptin, a hormone secreted by adipose tissue, regulates energy allocation to functions as diverse as feeding, sleep, reproduction and immunity. Despite evidence that leptin influences reproductive trade-offs, its role as a putative regulator of courtship display is poorly understood. Here we examine the use of interoceptive and exteroceptive cues to modulate display effort in Alston's singing mouse, Scotinomys teguina. We manipulated individual perception of energy balance through intraperitoneal injection of exogenous leptin, and we manipulated social context through playback of conspecific song. Leptin-injected mice responded with song to playback more frequently and more quickly than saline-injected controls. Although leptin seems to promote increased song effort, we found that leptin also reduced song duration. Song effort increased after leptin injection and playback of conspecific songs. Understanding the mechanisms by which animals respond to internal and external cues broadens our understanding of context-dependent display as well as behavioural plasticity more generally.

Courtship displays have been traditionally considered stereotyped behaviours. Many elaborate courtships are displayed in specific locations or in courts prepared by the displaying individuals. Sudden environmental events may alter the spatial structure of the displaying site, and individuals should be able to cope with such disruptions. In some mating systems, courtship is the only or main trait used in mate choice. This is the case in lek mating systems where male mating success is highly skewed and intense sexual selection may drive the evolution of elaborate courtship. The golden-collared manakin is a lekking species of the Neotropical forests. Males have an elaborate courtship display that includes a series of acrobatic jumps within a court delimited by small saplings. The courtship ends with a jump on one of the saplings, called the mating sapling, which invites the female to copulate. The display of each male follows a consistent routine that males establish at the beginning of the reproductive season. We hypothesized that males possess behavioural flexibility to adapt their courtship behaviour to unpredictable environmental changes. We investigated the effects of a sudden disruption of the court configuration by placing a piece of bark on the mating sapling. Males gradually established a new display sequence with an alternative mating sapling, demonstrating a high level of behavioural flexibility that suggests the involvement of motor learning. When the bark was removed, some males reverted to the original sequence, showing retention of the original display sequence. Our study provides evidence for the involvement of motor learning in the establishment and adjustment of elaborate courtship displays.

Based on the unusual characteristics of the male pedipalp and male genital morphology, a new genus and new species of Gagrellinae harvestmen, Thunbergia gretae n. gen. n. sp. (male and female) from Shaanxi Province, China, is proposed. The tibia and tarsus of the pedipalp form elaborate palpal claws, resembling gaspipe pliers, probably used to grasp the legs or the pedipalps of the female during courtship. There is no comparable modification of the pedipalp in the female. The penis lacks wing or sac-like (saccate) elements normally present in Gagrellinae, and the penis base is markedly inflated to form a bulb-like structure harbouring the penis muscle. Two or three opisthosomal tergites are fused to the opisthosomal scute and, in combination, cause the male and female bodies to appear elongated and slender. Three further species belong to Thunbergia n. gen., namely Thunbergia grandis (Roewer 1912), Thunbergia wangi (Zhu & Song 1999) and Thunbergia zhui (Zhang & Zhang 2013). The genus Melanopa Thorell, 1889, to which the new species T. gretae n. sp. superficially seems to belong, is re-defined by revision of the type species from Burma (now Myanmar). With respect to courtship behaviour morphological interdependence of penial and of pedipalpal structures within Gagrellinae and Leiobuninae are addressed.

Courtship and mating behavior were investigated in four species, representing three different genera, in the family Pachytroctidae. All exhibited a lengthy courtship in the male-above position followed by brief copulation in the female-above position with both facing in the same direction. This courtship behavior has not previously been observed in ‘Psocoptera’ and may be unique to Pachytroctidae. In three of the species in this study, the spermatophore remnant protruded from the tip of the male’s abdomen after copulation, and was immediately deposited on the surface of the experimental enclosure. Differences in courtship behavior of the two closely related and sympatric Tapinella species, described in this report, may represent reproductive isolating mechanisms. Under experimental conditions, we observed a male of each Tapinella species mount, court, and attempt to mate with a virgin female of the other species. In each case the female rejected the male and failed to mate. Implications relative to these behaviors are discussed. DOI links to videos are provided for easy access.

Females of the sevenspine goby Gymnogobius heptacanthus are more colorful and active in courtship display than males. Females tend to exhibit agonistic behavior in female-female competition reaching its highest level in their completed readiness to spawn. In addition, females are sex-role reversed, performing courtship displays. Fish behavioral patterns are rather simple. Thus, the level of male aggression is very low. They do not initiate any courtship display. The spawning ground is not a strictly-guarded site of importance. A small number of male spawners can be a key factor for the sex-role reversal occurrence.

Effects of hexane extract of Lantana camara leaves were investigated on reproductive bioactivities of Dysdercus koenigii by assessing mating behavior, oviposition behavior and fertility of the adults emerged from treated fifth instar nymphs. Leaves of L. camara were extracted in hexane by ‘cold extraction method’. The fifth instar nymphs were treated with the extract by ‘dry film residual method’ for 24 h and the adults emerged from these nymphs were used for the experiments. The results indicated that treated males showed altered courtship behaviour, lesser number of mounting attempts and took relatively more time to mate than the normal males. The treated females, very often, exhibited mating refusal and non-receptive behaviour towards the courting males. This led to decrease in percent successful mating. Also, the mating in the treated insects frequently got disrupted and terminated prior to insemination. The treatment of the females with the extract resulted in alteration of their oviposition behaviour. Consequently, the treated females laid lesser number of egg batches and total number of eggs in their life span. Although the eggs laid by the treated females were fertile, the percent hatchability was lesser than normal. The results signify that hexane leaf extract of L. camara possesses phytochemicals, which adversely impaired the reproductive bioactivities of D. koenigii. Therefore, some of these compounds individually or synergistically can be employed in integrated pest management of D. koenigii by hampering its reproductive potential.

The Western Ghats have a high level of anuran endemism. Although there has been an extensive focus on their taxonomy, the ecology of most species are poorly known. In this note we describe the reproductive life-history traits and breeding behavior of four species of endemic bush frogs, Pseudophilautus wynaadensis, Raorchestes akroparallagi, Raorchestes glandulosus, and Raorchestes ponmudi (Amphibia: Anura: Rachophoridae) from Wayanad region of Western Ghats.

The handicap hypothesis predicts that more elaborate males attract more predators, but are also better able to escape attacks. Thus, a unit increase in trait elaboration has a lower cost for a high-quality male (i.e., differential cost). Although widely accepted, the handicap hypothesis has seldom been appropriately tested, especially concerning the differential cost assumption. Here, we tested this assumption using the jumping spider Hasarius adansoni. The courtship display of male H. adansoni involves bright white patches that contrast with their dark-coloured body. In experimental trials, we measured male escape capacity following a simulated predatory attack. Measurements of escape capacity were correlated to the size of white patches. Contrary to expectations, spiders with larger white patches did not exhibit better escape capacity. We conclude that this trait does not function as a handicap. It is possible that other sexual selection processes are at work.

Characterisation of distance sex pheromones in decapods is challenging, although great efforts have been made in this field in the past 50 yr. In a previous study, we identified a component of the distance (soluble) sex pheromone bouquet of the peppermint shrimp Lysmata wurdemanni as being a uridine-5’-di-phosphate (UDP)-like chemical. However, UDP itself does not elicit the full pre-copulatory ‘approach and follow’ behaviour in peppermint shrimp. Here, we tested the hypothesis that the UDP-like chemical is uridine-5’-tri-phosphate (UTP), a metabolic product of chitin synthesis, and that this is the component of the distance sex pheromone of L. wurdemanni. We ran a series of bioassays to examine whether UDP, UTP or mixtures of the 2 compounds elicit male mating behaviour. Our results showed that male L. wurdemanni responded to UTP by displaying stereotyped courtship behaviour—the same behaviour elicited from males when exposed to water that previously contained moulting females. Combining UTP and UDP did not enhance the intensity of this courtship behaviour. The minimum effective concentration of UTP found to elicit courtship behaviour in the male shrimp was between 10-6 and 10-7 M. HPLC analysis showed the presence of UTP in the moulting water of female shrimp and also the partial conversion of UTP to UDP during the sample preparation procedure. Both the bioassay and chemical analysis results presented in this study suggest that UTP is a component of the distance sex pheromone in L. wurdemanni, and that the major peak in the chromatogram of a L. wurdemanni pheromone identified in previous studies might be a breakdown product of UTP.

Sexually selected traits can be expected to increase in importance when the period of sexual behavior is constrained, such as in seasonally restricted breeders. Anolis lizard male dewlaps are classic examples of multifaceted signaling traits, with demonstrated intraspecific reproductive function reflected in courtship behavior. Fitch and Hillis found a correlation between dewlap size and seasonality in mainland Anolis using traditional statistical methods and suggested that seasonally restricted breeding seasons enhanced the differentiation of this signaling trait. Here, we present two tests of the Fitch–Hillis Hypothesis using new phylogenetic and morphological data sets for 44 species of Mexican Anolis. A significant relationship between dewlap size and seasonality is evident in phylogenetically uncorrected analyses but erodes once phylogeny is accounted for. This loss of strong statistical support for a relationship between a key aspect of dewlap morphology and seasonality also occurs within a species complex (A. sericeus group) that inhabits seasonal and aseasonal environments. Our results fail to support seasonality as a strong driver of evolution of Anolis dewlap size. We discuss the implications of our results and the difficulty of disentangling the strength of single mechanisms on trait evolution when multiple selection pressures are likely at play., Using new data sets, we retested support for a correlation between anole dewlap size and seasonality. Our results suggest that the previously recognized pattern of larger dewlaps in highly seasonal environments, independently verified in our study, is explained by shared evolutionary history.

The effects of Bisphenol A (BPA) on selected behaviors of Drosophila melanogaster, namely larval feeding rate, larval foraging ability, adult climbing ability and courtship display, were tested by rearing the flies for 30 successive generations by exposing the third instar larvae to two different sublethal doses (0.007 g/2 ml and 0.010 g/2 ml). Our results revealed a significant reduction in feeding rate, foraging path length and frequency of courtship display. Both the treated male and female adults exhibited higher climbing ability at lower concentration (0.007 g/2 ml) of BPA exposure at 20 s and 30 s of interval, whereas reduced climbing ability was recorded at 10 s of interval in comparison with controls. At higher concentration (0.010 g/2 ml), only the treated females, not males exhibited significant reduced climbing ability at 30 s of interval.

The existence of ovulatory-cycle shifts in women’s mate preferences has been a point of controversy. There is evidence that naturally cycling women in their fertile phase, compared with their luteal phase, evaluate specific behavioral cues in men as more attractive for sexual relationships. However, recent research has cast doubt on these findings. We addressed this debate in a large, preregistered, within-participants study using salivary-hormone measures and luteinizing-hormone tests. One hundred fifty-seven female participants rated the sexual and long-term attractiveness of 70 men in dyadic intersexual interactions in natural videos. Multilevel comparisons across two ovulatory cycles indicated that women’s mate preferences for men’s behaviors did not shift across the cycle for either competitive or courtship behavior. Within-women hormone levels and relationship status did not affect these results. Hormonal mechanisms and implications for estrus theories are discussed.

The red-sided garter snake exhibits a dissociated reproductive pattern, mating at a time when their gonads are quiescent and circulating sex steroids, initially reported to be low, have been found to be elevated during the breeding season. However, the only cue identified that initiates courtship behavior and mating in the red-sided garter snake is an extended period of low-temperature dormancy (LTD) followed by exposure to warm temperatures. In this study, we examined a possible association between winter dormancy, sex steroid hormone metabolism, and initiation of reproductive behavior in the male red-sided garter snake. Upon emergence from winter dormancy, courtship behavior was assessed using attractive females as stimuli. Animals receiving implants containing 1,4,6-androstatriene-3,17-dione (ATD), an aromatase inhibiter, showed little or no courtship behavior, while animals implanted with ATD + 17β estradiol (E2 ) or blank implants exhibited normal courtship. In addition, neurons in the pathways critical in the control of reproductive behavior were examined using the Golgi method. Examination of brains collected upon emergence revealed animals implanted with ATD had a significantly reduced number of dendritic spines compared to controls and animals treated with ATD + E2 . This study provides the first documentation that courtship behavior and mating in the male red-sided garter snake appears to be controlled not by LTD alone, but in conjunction with sex steroid hormones. Moreover, behavioral data suggest that the aromatization of androgens during LTD appears to be critical for the initiation of reproductive behavior in the male red-sided garter snakes.

Species of flies in the genus Drosophila differ dramatically in their preferences for mates, but little is known about the genetic or neurological underpinnings of this evolution. Recent advances have been made to our understanding of one case: pheromone preference evolution between the species D. melanogaster and D. simulans. Males of both species are very sensitive to the pheromone 7,11-HD that is present only on the cuticle of female D. melanogaster. In one species this cue activates courtship, and in the other it represses it. This change in valence was recently shown to result from the modification of central processing neurons, rather than changes in peripherally expressed receptors, but nothing is known about the genetic changes that are responsible. In the current study, we show that a 1.35 Mb locus on the X chromosome has a major effect on male 7,11-HD preference. Unfortunately, when this locus is divided, the effect is largely lost. We instead attempt to filter the 159 genes within this region using our newfound understanding of the neuronal underpinnings of this phenotype to identify and test candidate genes. We present the results of these tests, and discuss the difficulty of identifying the genetic architecture of behavioral traits and the potential of connecting these genetic changes to the neuronal modifications that elicit different behaviors.

Previously, we described gene factor of interpulse interval (fipi, aka CG15630), whose decreased expression in the nervous system led to the changes in the parameters of a pulse song—a component of courtship in Drosophila males, in particular, to the reduction of the interpulse interval (Fedotov et al. 2014). In this study, we describe the structures of the nervous system, where the fipi gene is expressed. We also examine the role of this gene in courtship behavior, including its modification as a result of previous experience of a male courting a non-receptive fertilized female. It is known that such experience (learning) reduces the intensity of subsequent courtship of a male as regards other females. The expression of the GFP marker protein under control of the fipi gene promoter was detected in local interneurons of the antennal lobes, in Kenyon gamma-neurons, and in visual neurons of the optical lobes. The blocking of synaptic transmission from fipi-neurons reduced the efficiency of courtship suppression, and increased the excitability of these neurons, which resulted in a longer retention of the suppression effect. The knockdown of the fipi gene did not cause abnormalities in the courtship suppression, instead, it increased courtship intensity in males with no experience. The results show that fipi neurons are involved in the regulation of courtship behavior, and suggest that the expression of the fipi gene in gamma-neurons of mushroom bodies is involved in the formation of a short-term memory in this form of learning.

Motivational states are important determinants of behavior. InDrosophila melanogaster, courtship behavior is robust and crucial for species continuation. However, the motivation of courtship behavior remains unexplored. We first find the phenomenon that courtship behavior is modulated by motivational state. A male fly courts another male fly when it first courts a decapitated female fly however, male– male courtship behavior rarely occurs under normal conditions. Male flies that have satisfied the need for sexual behavior show a decreased male–female sex drive. Therefore, in this phenomenon, the male fly’s courtship motivational state is induced by its exposure to female flies. Blocking dopaminergic neurons by expressing TNTe decreases motivational state-induced male–male courtship behavior without affecting male–female courtship behavior. Vision cues are another key component in sexually driven male–female courtship behavior. Here, we identify a base theory that the inner motivational state could eventually decide fly behavior.

An individual’s decision to engage in courtship depends on external cues from potential mates and internal cues related to maturation, health, and experience. Hormones allow such information to be conveyed to distal tissues in a coordinated fashion. Here, we show Ecdysis-Triggering Hormone (ETH) is a regulator of male courtship in Drosophila melanogaster, and critical for mate choice and courtship inhibition after the completion of copulation. Preventing ETH release increases male-male courtship and decreases post-copulation courtship inhibition (PCCI). Such aberrant male courtship behavior in ETH-deficient males appears to be the consequence of inabilityto integrate pheromone cues into decision making. Silencing of ETH receptor (ETHR) in GR32A-expressing neurons leads to reduced ligand sensitivity and elevated male-male courtship. We find OR67D is critical for suppression of courtship after mating, and ETHR silencing in OR67D-expressing neurons, and GR32A-expressing neurons to a lesser degree, elevates post-copulation courtship. Finally, ETHR silencing in the corpus allatum increases post-copulation courtship; treatment of with juvenile hormone analog partially restores normal post-mating behavior. ETH, a stress-sensitive reproductive hormone, appears to coordinate multiple sensory modalities to guide Drosophila male courtship behaviors, especially after mating.

Male sexual behavior in Drosophila melanogaster, largely controlled by the fruitless (fru) gene encoding the male specific FruM protein, is among the best studied animal behaviors. Although substantial studies suggest that FruM specifies a neuronal circuitry governing all aspects of male sexual behaviors, recent findings show that FruM is not absolutely necessary for such behaviors. We propose that another regulatory gene doublesex encoding the male-specific DsxM protein builds a core neuronal circuitry that possesses the potential for courtship, which could be either induced through adult social experience or innately manifested during development by FruM expression in a broader neuronal circuitry. FruM expression levels and patterns determine the modes of courtship behavior from innate heterosexual, homosexual, bisexual, to learned courtship. We discuss how FruM expression is regulated by hormones and social experiences and tunes functional flexibility of the sex circuitry. We propose that regulatory genes hierarchically build the potential for innate and learned aspects of courtship behaviors, and expression changes of these regulatory genes among different individuals and species with different social experiences ultimately lead to behavioral diversification.

Animals often exhibit conspicuous, and sometimes curious, courtship traits, such as nestling-like courtship display in birds, though modern studies of nestling-like courtship display (and calls) are virtually lacking. An exception is previous experiments on the barn swallow Hirundo rustica, demonstrating that females are equally attracted to playback of two structurally similar calls, nestling-like male courtship calls and nestling food-begging calls. The experiments support the sensory trap hypothesis, i.e., that male signals mimic nestling stimuli to exploit female parental care for nestlings. However, female attraction might not be the sole function of nestling-like traits, and males might also have a sensory bias toward nestling-like traits, in which males would be less aggressive toward characteristics typical of immature individuals. Here, I conducted playback experiments to study the function of nestling-like male courtship calls in the context of male–male interactions. Playback of male courtship songs induced frequent approaches by neighbouring males, while nestling-like male courtship calls or nestling food-begging calls induced fewer approaches, though male responses to the latter two vocalisations increased when approaching the nestling period. The observed pattern indicates that, by mimicking immature individuals, males attract intended signal receivers (i.e., females) while avoiding interference from eavesdroppers (i.e., neighbouring males). This unique function can explain why species with parental care exhibit immature-like behaviour.

Neuropeptides, including oxytocin-like peptides, are a conserved group of hormones that regulate a wide range of social behaviors, including vocal communication. In the current study, we evaluate whether putative brain sites for the actions of isotocin (IT), the oxytocin (OT) homolog of teleost fishes are associated with vocal courtship and circuitry in the plainfin midshipman fish (Porichthys notatus). During the breeding season, nesting males produce advertisement calls known as "hums" to acoustically court females at night and attract them to nests. We first identify IT receptor (ITR) mRNA in evolutionarily conserved regions of the forebrain preoptic area (POA), anterior hypothalamus (AH), and midbrain periaqueductal gray (PAG), and in two topographically separate populations within the hindbrain vocal pattern generator- duration-coding vocal prepacemaker (VPP) and amplitude-coding vocal motor nuclei (VMN) that also innervate vocal muscles. We also verify that ITR expression overlaps known distribution sites of OT-like immunoreactive fibers. Next, using phosphorylated ribosomal subunit 6 (pS6) as a marker for activated neurons, we demonstrate that ITR-containing neurons in the anterior parvocellular POA, AH, PAG, VPP, and VMN are activated in humming males. Posterior parvocellular and magno/gigantocellular divisions of the POA remain constitutively active in nonhumming males that are also in a reproductive state. Together with prior studies of midshipman fish and other vertebrates, our findings suggest that IT-signaling influences male courtship behavior, in part, by acting on brain regions that broadly influence behavioral state (POA) as well as the initiation (POA and PAG) and temporal structure (VPP and VMN) of advertisement hums.

Antennae and maxillary palps are the most important chemical reception organs of flies. So far, the morphology of antennae and maxillary palps of flies of most feeding habits have been well described, except for that of relatively rare aquatic predatory species. This study describes sensilla on antennae and maxillary palps of three aquatic predatory Lispe species: Lispe longicollis, L. orientalis and L. pygmaea. Types, distribution, and density of sensilla are characterised via light and scanning electron microscopy. One type of mechanoreceptors is found on antennal scape. Mechanoreceptors (two subtypes) and one single pedicellar button (in L. pygmaea) are located on antennal pedicel. Four types of sensilla are discovered on antennal postpedicel: trichoid sensilla, basiconic sensilla (three subtypes), coeloconic sensilla and clavate sensilla. A unique character of these Lispe species is that the coeloconic sensilla are distributed sparsely on antennal postpedicel. Mechanoreceptors and basiconic sensilla are observed on the surface of maxillary palps in all three species. We demonstrated clear sexual dimorphism of the maxillary palps in some of the Lispe species, unlike most other Muscidae species, are larger in males than females. This, along with their courtship dance behaviour, suggest their function as both chemical signal receiver and visual signal conveyer, which is among the few records of a chemical reception organ act as a signal conveyer in insects.

Mating behaviour of the leucosiid crabPyrhila pisumwas studied in the laboratory and tidal flats in Japan. Most males actively approached females. Males started guarding females without any courtship behaviour (pre-copulatory guarding). Males began copulation within several minutes. The copulation continued for about 1–2 h, following which males began post-copulatory guarding. This guarding lasted from almost 0 to over 3 days, but its duration was generally much longer than that prior to copulation. Release of guarding was not linked to ovulation by females. Long-term rearing experiments revealed that both sexes ofP. pisumcould copulate multiple times with various mates. Developmental stages of the embryos recorded from copulating ovigerous females widely varied; their timing of copulation may not be fixed. In the tidal flat, wandering males frequently contacted with other individuals, but without distinguishing single males, single females and pairs ofP. pisum, orHemigrapsus takanoi. MaleP. pisumcannot recognize female conspecifics, and they approach their mates relying only on vision, without using any attractive cues from females. In cases in which males encountered pairing crabs, they successfully stole the females when the guardians were smaller than the challengers, suggesting that effectiveness of guarding depends on male size. Among the mating pairs, males tended to be larger than females, and the tendency of size-assortative mating was weak or absent. Therefore, the mating behaviour ofP. pisumis not elaborate, although their guarding behaviour may contribute to improve success to some degree.