Ethology最新文献

Facultative parthenogenesis is a form of reproduction in which females can either lay unfertilised eggs that typically develop into female offspring only or mate and lay fertilised eggs that develop into male and female offspring. Intriguingly, facultative parthenogens often occur in mixed-sex populations where reproduction is mostly sexual and all-female populations where reproduction is asexual. How all-female populations avoid invasion by males remains unknown. Here, we explored the use of pheromones in male–female communication in a facultatively parthenogenetic stick insect, the peppermint stick insect (Megacrania batesii), and compared chemical signals between females descended from sexually versus parthenogenetically reproducing populations. If parthenogenetic females release less attractive pheromones, this could help explain the persistence of all-female populations. We found that M. batesii exhibits slight sexual dimorphism in antenna morphology, and behavioural assays provided little evidence that males could locate females solely by volatile pheromones. However, CHC profiles differed substantially between different types of females. Analysis of CHC components indicated a clear genetic difference between females descended from all-female versus mixed-sex populations, as well as a maternal effect of female parthenogenetic versus sexual development. Together, our results suggest that males might rely more on close-range chemical cues to differentiate females, and chemical communication could play a role in the persistence of all-female populations.

Estimating repeatability allows a first approximation that may indicate a potential response to selection of sexual traits. Acoustic sexual signals comprise spectral and temporal variables, where the former generally have lower intra-individual variation and higher repeatability values. Studies of repeatability in anurans have been conducted mainly in natural conditions, but the stability of laboratory settings allows extended recording intervals, favoring measurement accuracy. We conducted a study of variation and repeatability of the calls of males of Batrachyla taeniata, a frog from the South American temperate forest to evaluate under homogeneous environmental and social conditions: (i) the extent of variation in acoustic properties of calls within and among days, (ii) the extent of temporal variation in the repeatability of call properties, and (iii) differences in repeatability among call variables. Variation of acoustic properties differed within and across days of recording, call rate generally increased within and throughout days, suggesting sensitization processes. Call duration decreased during these time spans, yielding constant calling effort. In contrast, the dominant frequency decreased within days but increased across days. Overall repeatability differs significantly among variables: dominant frequency, call rate, and call duration having the highest, intermediate, and lowest values, respectively. The high repeatability of call rate relative to call duration contrasts with an opposing general tendency in previous studies in anurans. The repeatability of the three variables analyzed increases within days, and the repeatability of call rate also increases throughout days, highlighting the relevance of this variable for individual identity over different time ranges.

Most animals live and move in a landscape in which the risk of predation varies spatially and temporally, that is, a “landscape of fear” which may strongly affect their ecology and behaviour. Cavity-nesting birds prospecting for nest sites are often forced to investigate unfamiliar, dark holes that may be dangerous to enter because they may conceal an aggressive nesting bird or a predator. The Fear of Feathers Hypothesis posits that some birds such as blue tits Cyanistes caeruleus, add large, conspicuous feathers on top of their own nest to exploit the fear of potential nest usurpers or brood parasites. Feathers may trigger fear in prospecting birds either because the feathers obstruct the view of the cavity interior, and/or because the feathers may be perceived as recent prey remains and suggest the predator will return. Here I studied the prospecting behaviour of unmated male pied flycatchers Ficedula hypoleuca by letting them choose between a dyad of nest boxes where one contained a nest of a great tit Parus major and one a nest of a blue tit. The objective was to test whether the presence of feathers would have a stronger repelling effect than the species that had built the nest. Great tits are larger than blue tits and may represent a greater threat to intruding flycatchers. However, blue tits but not great tits, often decorate their nest with large, conspicuous feathers. Consistent with the Fear of Feathers Hypothesis, flycatchers hesitated longer to enter blue tit than great tit nests but only if the blue tit nest contained feathers. The study has relevance to many species of birds that decorate their nest with feathers. It shows that a landscape may include aspects of fear that are important to animal behaviour although they may seem subtle and are easily overlooked.

Semiaquatic animals breed in environments with a mix of aquatic and terrestrial features, each requiring appropriate types of locomotion with differential energetic demands and containing different suits of predators. We surveyed calling locations of male Eastern Gray Treefrogs (Hyla versicolor) at our study pond to assess average composition of land/water substrates available to females during mate choice. We also conducted acoustic playback trials to examine whether the mate choice behavior of females was affected by approach substrate; that is, whether females had to swim or walk towards a potential mate. We found that mate preferences were not strongly affected by the substrate of movement: the preferred call duration (“peak preference”) was similar in both treatments, but females showed somewhat stronger discrimination against values deviating from their peak preference (higher “preference selectivity”) in the water treatment. By contrast, other aspects of phonotaxis behavior were clearly different and consistent with females perceiving water as a more dangerous environment: in the water treatment, females took longer to leave the dry release point, jumped further when leaving the release point, and took advantage of features of the playback setup (i.e., the aquatic arena was surrounded by walls) to leave the water and approach the speaker “on land”. This suggests that females do not compromise mate preferences but adjust associated behaviors to minimize risk, and that environmental heterogeneity has little influence on sexual selection regimes.

Bird song contains crucial information that enables recognition of conspecific individuals from a distance, which facilitates subsequent complex behaviors related to mate attraction and rival deterrence. Loud broadcast signals of non-learning bird species are usually treated as less complex than songs of Oscines, but several studies have revealed that song learning is not necessary for the evolution of complex signaling. Here, we focused on a species of African wood-dove which produces superficially simple songs consisting of short notes organized into two parts of different amplitude. Our model was a population of emerald-spotted wood-doves (Turtur chalcospilos) that live in the same area as the physically and vocally similar blue-spotted wood-dove (Turtur afer). We tested the responses of male emerald-spotted wood-doves to different playbacks simulating territorial intrusion. We used songs of the focal species and of the congener, two types of artificially mixed songs with different parts belonging to the focal or congeneric species, and a control song. We aimed to assess (i) whether the focal species responds only to its own species' song or exhibits interspecific territoriality, and (ii) which part of the song is responsible for coding species identity. We found that male emerald-spotted wood-doves responded strongly to playback, but almost exclusively approached only the playback of their own species' song. Additionally, only conspecific song caused a decrease in song rate during playback and an increase in song output after playback. Our results suggest that emerald-spotted wood-doves are able to discriminate their own songs from those of congeners and do not exhibit interspecies territoriality. We were unable to identify a single part of the song that codes species-specificity, as mixed songs of any kind did not substantially increase responsiveness to playback in comparison to the congener song or the control. We discuss these results in the context of current hypotheses regarding interspecific territoriality and the evolution of species-identity coding.

Retraction: Pruitt, J. N., Burghardt, G. M., & Riechert, S. E. (2011). Non-conceptive sexual behavior in spiders: A form of play associated with body condition, personality type, and male intrasexual selection. Ethology, 118(1), 33–40. https://doi.org/10.1111/j.1439-0310.2011.01980.x

The above article, published online on October 23, 2011 in Wiley Online Library (wileyonlinelibrary.com) has been retracted by agreement between the Journal's Editor-in-Chief, Wolfgang Goymann, and Wiley-VCH GmbH. The retraction has been agreed upon following concerns raised about the validity of the quantitative data reported. J.N. Pruitt, the corresponding author, did not respond following repeated requests to provide the primary data. During the investigation, coauthors S.E. Riechert and G.M. Burghardt requested retraction because they would have no way to validate the article's conclusions without those data. The coauthors have lost confidence in the conclusions of the article, as have the editors and Wiley, hence our decision to retract. Corresponding author J.N. Pruitt was informed of the decision but has remained unresponsive.

Kodama, T., & Mori, A. (2023). How important is temperature for strike success of ectotherms? Thermal effects on predator–prey interactions of free-ranging pit vipers (Gloydius blomhoffii). Ethology, 129, 641–648.

In figure 2, the color of a plot (Strike outcome: “Hit”, Tb: 18.69°C, Dist.: 10 cm) is incorrect. The color of the plot should not be black but gray. The corrected figure 2 is shown below.

We apologize for this error.

Body size is often a critical determinant of competitive ability and reproductive behavior. For example, small males characteristically lose contests with larger males and may be metabolically constrained from sustaining energetically demanding reproductive behaviors. Small males thus often utilize alternative reproductive tactics (ARTs) to maximize their reproductive success. How variation in body size among behavioral phenotypes arises can provide important insight into the maintenance of ARTs. For instance, smaller body sizes for males adopting ARTs may simply be a function of age, suggesting that the tactic is maintained by the periodic recruitment of young males into the population. Alternatively, body size differences among behavioral phenotypes that are unrelated to age suggest disparate growth rates that potentially arise as a consequence of variation in environmental conditions during development or genotypic differences between the phenotypes. Here we examine these alternative scenarios in the green treefrog, Dryophytes cinereus, using skeletochronological analysis combined with body size measures. As with many other anuran amphibians, male green treefrogs conditionally adopt a noncalling satellite mating tactic and attempt to intercept females attracted to the vocalizations of calling “host” males. We show that males adopting satellite behavior in natural choruses are smaller than calling males but do not represent a class of younger individuals, indicating that satellite males have lower growth rates than calling males. We also show that satellite males are in poorer condition than larger calling males, implicating energetic constraints in size-related variation in mating tactic expression. Our work suggests that environmental conditions during development, genetic differences between phenotypes, or both, give rise to size discrepancies in behavioral phenotypes, neither of which have been previously explored in anurans. We discuss body size and condition differences between behavioral phenotypes in the context of energetic constraints and endocrine mediation of tactic expression in this species.

Sexual selection is an important evolutionary force and despite extensive research, understanding mate choice on naturally occurring trait variation remains an intriguing area of study. The correlation between mass, a trait associated with courter viability and common target for mate choice, and signals is particularly noteworthy. This study focuses on Schizocosa mccooki, the largest member of a wolf spider genus renowned for its diverse complex male courtship. Our objective was to understand the relationship of male mass and other courtship signals on female choice within this species. We conducted lab experiments involving random pairings of field caught males and females, recording vibratory courtship and its outcomes. Our findings revealed that S. mccooki courtship consisted of vibratory signals with two major components, thumps and raps. Male mass, overall courtship vigor, and thump duration were found to predict mating success. Interestingly, we found no correlation between temporal traits and mass suggesting independent information and an absence of trade-offs between mass, courtship vigor, and signal component rates/durations. Instead, we found that heavier males tend to produce thumps with lower frequencies. The finding that male mass predicts mating success contrasts with patterns observed in other species in this well-studied genus. By uncovering the mate choice patterns of S. mccooki, this study underscores the importance of comparative studies to understand the ways in which sexual selection drives diversification, even among closely related taxa.

Carcasses are patchily distributed and often short-lived resources, placing scavenging animals under pressure to locate them before they rot or are depleted by competitors. Scavengers may search for carcasses directly, or indirectly, using social information. Aggregations of feeding animals and their conspicuous competitive behaviour may be more readily detectable to searching scavengers than the carcass itself. Moreover, the actions of attendant scavengers upon the carcass, breaking it apart and releasing odour or chemical cues, may further enhance its detectability to others foraging nearby. Here we test this idea. In the first of two experiments performed in the field, we found that hermit crabs (Pagurus bernhardus) were attracted to shelled mussels (Mytilus edulis) that other hermit crabs were already feeding on. They showed no strong tendency to approach aggregations of conspecifics in the absence of food, nor conspecifics that were confined close to mussels but prevented from feeding on them. We speculated that through breaking up the carcass, the feeding hermit crabs released chemical cues and drifting particles of mussel tissue that further attracted other hermit crabs. We tested this in a second experiment, finding that finely chopped mussels attracted significantly more hermit crabs than did intact mussels. We suggest that scavenger feeding action upon carcasses makes these more detectable to others by releasing odour and particle plumes, a form of inadvertently produced social information.