Animal Behaviour最新文献

Species recognition can be interpreted as the identification of sexual compatibility among individuals, which is related to the assessment of partner quality. This compatibility can be assessed using visual signals of conspecifics such as body coloration. Fiddler crabs constitute a group with a global distribution, comprising over 100 species with diverse colours. They perceive these body colours and use them for intersexual communication, primarily through signalling of the hypertrophied claw of males. However, few species have been investigated regarding the role of body coloration as a species-specific signal, and it remains unknown whether other body regions, such as the carapace, convey information about individual quality or species identity. Hence, this study aimed to examine whether carapace coloration of two sympatric fiddler crab species (Leptuca leptodactyla and Leptuca cumulanta) affects species recognition. To do this, we used individual females of L. leptodactyla that were subjected to a binomial choice of males with claws and carapaces reflecting different colours, simulating conspecifics (L. leptodactyla) or heterospecifics (L. cumulanta). We observed that females were unable to distinguish conspecifics from heterospecifics using only claw colour. On the other hand, we discovered that the white carapace coloration of L. leptodactyla was crucial for females to identify conspecific males. This is the first study to demonstrate that carapace coloration of male fiddler crabs functions in species recognition, reinforcing the idea that body traits beyond sexual ornaments can influence animal communication, affecting species identity and/or mate selection.

Growing research on the function of female birdsong now allows for identification of large-scale patterns emerging in the published literature. We conducted a review that analysed female birdsong function studies to characterize the literature and research approaches in this field. We examined when, where and how researchers study female birdsong function and then quantified which functions for female song were most often supported by authors. Our data set included studies published between 1900 and 2022 that concentrated on singing female birds and either investigated or addressed functions of solo female song directly. The number of female song studies published per year has increased rapidly in recent decades, with the majority of the work focused on North/Central American species, followed by Australian and South American species. Most research studies used natural observation techniques, about half used playback and only 21% used other manipulations. In 67% of the studies analysed, female song was reported to be used in defence of a territory, 43% of studies reported intrasexual competition/aggression and 45% reported intrapair communication. Mate attraction and parent–offspring communication were the song functions least often supported and least often tested by authors. Most authors identified multiple contexts in which female song functioned in each study species. Outcomes match the demonstrated multifunctionality of male birdsong. In contrast, females apparently use song for mate attraction much less than male birds do. Surprisingly, less than 10% of papers directly linked female song behaviour to reproductive success, a connection providing critical support for ultimate explanations of function. It is evident that scientific interest in female birdsong function is on the rise. Our review identified a need for future research to include African and Asian avian species and studies that comprehensively test the fitness correlates of female birdsong function.

Aggressive interactions can strongly influence an animal's performance in subsequent contests. Winners of aggressive contests are more likely to win successive contests and losers are more likely to lose successive contests. Such winner and loser effects can significantly influence an animal's dominance status, ability to acquire resources and reproductive success. Thus, quantifying the magnitudes of winner and loser effects across taxa is important for our understanding of hierarchy formation, life history trade-offs and reproductive tactics in different species. Furthermore, it is unclear whether the magnitude of winner effects differ from that of loser effects. Finally, experimenters often employ one of two distinct methods for quantifying the strength of winner and loser effects: self-selection and random assignment. Due to selection bias, it is possible that self-selection protocols overestimate the magnitude of winner and loser effects. We therefore systematically searched the literature to conduct a comprehensive meta-analysis of winner and loser effects. We analysed a total of 168 effect sizes from arachnids, crustaceans, fishes, insects, mammals and reptiles. We found that prior winners tend to win approximately two-thirds of their subsequent fights, while prior losers tend to lose approximately two-thirds of their subsequent fights. While we did not find that studies using self-selection generated effect size estimates that significantly differed from random assignment protocols, future studies should still avoid self-selection protocols. Overall, our study highlights the ubiquity of winner and loser effects across the animal kingdom and suggests several avenues for future research to unravel the evolutionary origins and mechanistic underpinnings of such experience effects.

Assessing social effects on individual behaviour is challenging because knowledge of an individual's social environment is often difficult to gain, especially for animals that form dynamic social groups. We here report on an experiment where the social environment could be manipulated. To this end, we capitalized on the availability of populations of migrant and resident sticklebacks, Gasterosteus aculeatus, that exhibit strong differences in movement tendencies. This allowed us to create mixed shoals with different proportions of migrants and residents, to investigate the occurrence of social effects between migrant and resident fish. In a mesocosm consisting of linearly connected ponds, we found that the overall movement patterns, as quantified by the number of pond transitions, remained consistently higher in migrants than in residents, regardless of the social group composition. The fish's intrinsic movement tendency was the main predictor of the observed variation between populations. However, at the start of the experiment, when social effects were expected to be strongest, residents were more likely to leave the starting pond in the presence of migrants than in their absence. As this increase in movement tendency was not related to the frequency of migrants in the mixed groups it cannot solely be ascribed to social conformity. Additionally, we found an effect of being part of the majority on movement: the first fish to leave the starting pond was almost always a member of the majority group (be it migrants or residents). In conclusion, we found little evidence for social modulation of movement based on differences in the populations' movement tendencies, but rather an effect of being in a majority group.

Learning is central to our understanding of how behaviour is shaped by the environment. A key open question is whether learning across contexts evolves as an integrated process, or whether learning in each context is free to evolve separately. Here, we measured learning in two sensory contexts in multiple genotypes and both sexes of two closely related, but ecologically divergent, species of fruit flies, Drosophila simulans and Drosophila sechellia. These species are morphologically very similar but differ dramatically in ecology and population biology. We tested how flies from each genotype, sex and species responded to and learned about different gustatory and visual cues. This approach allowed us to test whether species differences in learning were independent or correlated across contexts. Surprisingly, we found no evidence that D. simulans learned in any of our treatments. In contrast, D. sechellia learned to avoid gustatory stimuli that were paired with an aversive stimulus, as predicted, but unexpectedly learned to approach visual stimuli that were paired with the aversive stimulus. At the genotype level, genotypes, but not species, differed in their naïve responses to stimuli, but genotypes did not differ in learning in either species. Our results demonstrate that D. sechellia indeed differs from D. simulans in both learning contexts, but in a stimulus-dependent way. We suggest that studies of additional species or population pairs that employ this framework will be critical for evaluating the dimensionality of learning and its evolution.

Nectar-foraging bees change their use of floral resources as plant species appear in the environment and disappear over their lifetimes. The new flowers used may involve different cues and different nectar extraction tactics. Although bumble bees can adapt to changes in floral cues and required tactics, little is known about whether bees prioritize switching tactics or floral cues when deciding which plant species to switch to. In a laboratory assay, we forced common eastern bumble bee, Bombus impatiens, workers either to switch the handling tactic they were using or to continue using the tactic but to switch the colour of artificial flowers foraged on. We examined whether bees' tendency to change their tactics was influenced by how similar in colour novel flowers were to familiar ones. We conducted a 2 × 2 factorial experiment using artificial flowers, manipulating the handling tactic that bees were initially trained to use (legitimate visit or nectar robbing) and the similarity between novel and trained colours (similar or distinct). We found that under most conditions bees preferred to switch flower colours and retain handling tactics. However, when given experience with legitimate visits and when novel flowers were markedly different in colour from those they had experienced previously, bees tended to switch tactics while continuing to forage on flowers of the same colour. These findings suggest that the similarity in colour of a new floral resource to the currently exploited resource and the flower-handling tactic used by bees both play an important role in decision making by foraging bumble bees.

Details in birdsong parameters convey information about fitness, quality and motivational state of the signaller. Perception of these song details may affect decision making of receivers in territorial defence and mate choice. Whether the message in the song is perceived or not may have major consequences for the birds’ reproductive success. Consequently, birds may suffer fitness consequences from masking by other sounds in the environment. We conducted two different playback experiments to test whether song consistency, a sexually selected performance trait expressed in the temporal and spectral parameters of song, is perceived under different noise conditions. In the first experiment, we found that blue tits, Cyanistes caeruleus, are less able to assess the performance levels of song, but still detect the song stimuli under experimentally high broadband noise levels. Blue tits also responded with more songs overall, independent of song stimulus variation to playback of song stimuli under noisy conditions. When song stimulus variants were exposed simultaneously with a narrow band of noise in the second experiment, blue tits showed reduced capacity to discriminate only when the band of noise overlapped in frequency with the song. Results from this experiment support the notion that it is indeed the masking, rather than nonauditory effects of noise that cause the change in behaviour. Overall, our results show that there are noisy conditions that do not affect detection but still affect perception of information in the detailed structure of songs. Not being able to respond appropriately to songs that differ in performance level is likely to have negative fitness consequences and contribute to a detrimental impact of anthropogenic noise on individuals and populations.