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Spider webs are iconic examples of extended phenotypes that are remarkably plastic across different environments. Orb webs are not only effective traps for capturing prey, but can also provide information to potential mates and, in some cases, potential predators and prey through silk-based chemicals. As with regular phenotypic traits, variability in the properties of spider webs is thought to be mediated by a combination of genetic and environmental effects. Here, we examined variation in several key features of the webs of the orb-weaving spider Argiope keyserlingi across five geographically disparate populations. We documented variation in web architecture and chemical properties of webs collected directly from the field. We then probed the potential for the underlying environmental driver of local insect abundance to explain this variation, by analysing the properties of orb webs constructed by the spiders from these different populations, but under identical laboratory conditions. We found no evidence of variation across populations in the architecture of webs constructed in the laboratory, despite the large geographic distances. Nonetheless, we discovered between population variation in the composition of chemicals found on the surface of silk and in the taxonomic distribution of available prey. Furthermore, there was a positive correlation between the quantity of nitrogenous compounds in web silks and female body condition. When combined, these findings suggest that environmental mechanisms can drive variation in web traits across spider populations.

Theory predicts that males and females of dioecious species typically engage in an evolutionary sexual conflict over the frequency and choice of mating partner. Female sexual cannibalism, a particularly dramatic illustration of this conflict, is widespread in certain animal taxa including spiders. Nevertheless, females of some funnel weaving spiders that are generally aggressive to conspecifics enter a cataleptic state after male courtship, ensuring the males can mate without risk of attack. In this study, we demonstrated that the physical posture and duration, metabolites, and central neurotransmitters of females of Aterigena aculeata in sexual catalepsy closely resemble females in thanatosis but are distinct from those in anesthesia, indicating that the courted females feign death to eliminate the risk of potentially aggressive responses and thereby allow preferred males to mate. Unlike the taxonomically widespread thanatosis, which generally represents a deceptive visual signal that acts against the interest of the receivers, sexual catalepsy of females in the funnel weaving spiders may deliver a sexual-receptive signal to the courting males and thereby benefit both the signal senders and receivers. Therefore, sexual catalepsy in A. aculeata may not reflect a conflict but rather a confluence of interest between the sexes.

The perception of cues and signals in visual, olfactory and auditory modalities underpins all animal interactions and provides crucial fitness-related information. Sensory organ morphology is under strong selection to optimize detection of salient cues and signals in a given signalling environment, the most well-studied example being selection on eye design in different photic environments. Many dim-light active species have larger compound eyes relative to body size, but little is known about differences in non-visual sensory organ morphology between diurnal and dim-light active insects. Here, we compare the micromorphology of the compound eyes (visual receptors) and antennae (olfactory and mechanical receptors) in representative pairs of day active and dim-light active species spanning multiple taxonomic orders of insects. We find that dim-light activity is associated with larger compound eye ommatidia and larger overall eye surface area across taxonomic orders but find no evidence that morphological adaptations that enhance the sensitivity of the eye in dim-light active insects are accompanied by morphological traits of the antennae that may increase sensitivity to olfactory, chemical or physical stimuli. This suggests that the ecology and natural history of species is a stronger driver of sensory organ morphology than is selection for complementary investment between sensory modalities.

Theoretical models predict that virgin females at risk of not mating should strategically adjust their signalling investment as they age, with older, virgin females investing more to attract males. We explored how adult age influences the ‘calling’ (pheromone-releasing) behaviour of virgin female gumleaf skeletonizer moths, Uraba lugens, over four consecutive 10 h scotophases (dark periods). Adult virgin females commenced calling shortly after the onset of the scotophase. We found that female investment in calling behaviour changed with age: but in contrast with theoretical predictions and empirical observations in other species, older females were less likely to call and spent less time calling than younger females. Older females, however, commenced calling earlier in the scotophase, suggesting that there may be selection on older females to avoid competition from younger conspecific females. We also examined male olfactory preferences for pheromones from females of different ages. Y-maze assays showed that males preferred the pheromones produced by younger females, and that pheromone quality probably plays a role in this choice. Combined, these results suggest that female U. lugens may adaptively adjust their calling behaviour with age to mitigate against the risk of mating failure through competition with other females. The preference of males for pheromones produced by younger females is consistent with this interpretation.

Males of many moths possess scent organs, ranging from simple scales and hair-tufts to complex glands. Males of the gregarious beet webworm Loxostege sticticalis (Lepidoptera: Crambidae) display their ventroposterior brushes (VPBs), located on the eighth abdominal sternite, toward adjacent females and usually maintain this posture until sexually receptive females become available, or the arrival of photophase. The peak period of male L. sticticalis VPB display during the scotophase broadly coincides with that of mating. Our experiments revealed that females exposed to male VPB display increased their calling behavior and were more likely to mate than those exposed to males that did not display their VPBs. Volatile chemicals provide the only reliable sensory modality for intersexual communication in L. sticticalis because all behavioral assays were conducted in a sealed darkroom, thereby eliminating a role for visual signals, and no vibratory signals occurred during VPB displaying. Therefore, odors released from the VPB of male L. sticticalis may act as aphrodisiac signals to conspecific females in order to enhance female receptivity and increase his mating success. Our study indicates that chemical communication in these gregarious moths apparently involves mutually stimulating interactions between female attractant and male courtship pheromones.

Many animals improve their foraging success by producing signals that exploit the sensory biases of potential prey, but the specific properties that make these sensory traps effective remain unclear. We combine field experiments with phylogenetic comparative analyses to investigate the visual luring properties of different signal designs in web-building spiders. Our field experiments used cardboard spider models to examine the effects of area of colour patches, colour and pattern on the foraging success of the colourful giant wood spider, Nephila pilipes. These experiments revealed that both the colour (yellow) and pattern (yellow and black mosaic) are essential for luring prey in a high ambient light environment. We subsequently used phylogenetic comparative analyses to demonstrate an evolutionary association between prey viewing environment and spider ventral signal among 63 species of orb-weavers from 53 genera. Combined, our data show that (a) the colour of the bright body parts of orb-weavers is essential for both diurnal and nocturnal prey attraction, whereas the pattern and area of colour patches are important for diurnal foraging and (b) the evolution of these visual lures is associated with the viewing environment, specifically ambient light intensity. We conclude that the effectiveness of colour luring might be a major driver of the convergent evolution of yellow mosaic patterns in phylogenetically divergent orb-weavers. Our discoveries indicate that prey colour preferences and signal efficacy play a significant role in the evolution of visually mediated prey-luring systems. A free Plain Language Summary can be found within the Supporting Information of this article.

Carrion-feeding flies use odours emanating from the decomposing corpse as cues for oviposition and are described as generalists because the larvae feed on the corpses of diverse species. Whereas several features of the corpse may influence the oviposition choices of these flies, it is not known whether there is a preference for a particular species of corpse. We provided carrion flies with ovipositional (and feeding) choices in a field experiment, in which various odour sources were presented simultaneously. We found novel evidence of broadly consistent choices of carrion by flies from four families. Traps baited with decaying fish flesh captured the greatest number of individuals, whereas traps baited with decaying pig liver typically attracted the least. We also asked whether individuals captured in the various baits vary in antennal size, perhaps reflecting different capacities for odour detection. There was a trend for individuals of Lucilia sericata Meigen (Diptera: Calliphoridae) and the platystomatid collected from the traps baited with pig liver to have significantly larger antennae, whereas individuals of Muscina stabulans (Fallen) (Diptera: Muscidae) captured in traps baited with marine fish flesh had relatively longer antennae for their body size. Our data reveal a more nuanced pattern of oviposition behaviour in these generalist carrion flies, which may reflect differences in their preference of carrion with different nutrients, and in their capacity to detect particular odours.

Signals of resource-holding potential in dyadic (one-on-one) contests are relatively straightforward, typically reflected in the attributes of the individual, including body size and resource ownership. However, conveying this information is considerably more complex in social species: the outcome of collective contests will be influenced by both individual and group level effects, and the signal must be subsequently transmitted to the colony in order to elicit a colony response. Australian meat ants engage in collective displays where aggregations of many hundreds of pairs of workers from neighbouring colonies antennate one another while adopting a tip-toe posture with the abdomen raised. These displays rarely escalate into physical contests with their typically fatal consequences. A display between two workers may cease by one worker leaving or if one displaying worker is replaced by a nestmate. We asked whether these collective displays act to convey reliable information about relative colony size. Our field experiments and observations reveal that these displays do not necessarily convey precise information about relative colony size, and that it is possible for colonies to signal an exaggerated colony size, at least in the short term.

The reach of artificial light at night (ALAN) is growing rapidly around the globe, including the increasing use of energy-efficient LED lights. Many studies document the physiological costs of light at night, but far fewer have focused on the potential benefits for nocturnal insectivores and the likely ecological consequences of shifts in predator–prey relationships. We investigated the effects of ALAN on the foraging behaviour and prey capture success in juvenile Australian garden orb-web spiders (Eriophora biapicata). Laboratory experiments demonstrated that juvenile spiders were attracted to LED lights when choosing foraging sites, but prey availability was a stronger cue for remaining in a foraging site. Field experiments revealed a significant increase in prey capture rates for webs placed near LED lights. This suggests that any physiological costs of light at night may be offset by the foraging benefits, perhaps partially explaining recently observed increases in the size, fecundity and abundance of some orb-web spider species in urban environments. Our results highlight the potential long-term consequences of night lighting in urban ecosystems, through the impact of orb-web spiders on insect populations.

Animal colour patterns remain a lively focus of evolutionary and behavioural ecology, despite the considerable conceptual and technical developments over the last four decades. Nevertheless, our current understanding of the function and efficacy of animal colour patterns remains largely shaped by a focus on stationary animals, typically in a static background. Yet, this rarely reflects the natural world: most animals are mobile in their search for food and mates, and their surrounding environment is usually dynamic. Thus, visual signalling involves not only animal colour patterns, but also the patterns of animal motion and behaviour, often in the context of a potentially dynamic background. While motion can reveal information about the signaller by attracting attention or revealing signaller attributes, motion can also be a means of concealing cues, by reducing the likelihood of detection (motion camouflage, motion masquerade and flicker-fusion effect) or the likelihood of capture following detection (motion dazzle and confusion effect). The interaction between the colour patterns of the animal and its local environment is further affected by the behaviour of the individual. Our review details how motion is intricately linked to signalling and suggests some avenues for future research. This Review has an associated Future Leader to Watch interview with the first author., Summary: While motion can reveal information about the signaller, motion can also be a means of concealing cues by reducing the likelihood of detection or the likelihood of capture following detection.

Studies of sexual selection that occurs prior to mating have focussed on either the role of armaments in intra-sexual selection, or extravagant signals for inter-sexual selection. However, Darwin suggested that sexual selection may also act on ‘organs of sense’, an idea that seems to have been largely overlooked. Here, we refine this idea in the context of the release of sex pheromones by female insects: females that lower the release of sex pheromones may benefit by mating with high-quality males, if their signalling investment results in sexual selection favouring males with larger or more sensitive antennae that are costly to develop and maintain.

Light is fundamental to biological systems, affecting the daily rhythms of bacteria, plants, and animals. Artificial light at night (ALAN), a ubiquitous feature of urbanization, interferes with these rhythms and has the potential to exert strong selection pressures on organisms living in urban environments. ALAN also fragments landscapes, altering the movement of animals into and out of artificially lit habitats. Although research has documented phenotypic and genetic differentiation between urban and rural organisms, ALAN has rarely been considered as a driver of evolution. We argue that the fundamental importance of light to biological systems, and the capacity for ALAN to influence multiple processes contributing to evolution, makes this an important driver of evolutionary change, one with the potential to explain broad patterns of population differentiation across urban-rural landscapes. Integrating ALAN's evolutionary potential into urban ecology is a targeted and powerful approach to understanding the capacity for life to adapt to an increasingly urbanized world.

Lateralisation of biological form and function are well known for vertebrates and are being increasingly documented among invertebrates in recent years. Behavioural lateralisation in insects, together with asymmetrical distributions of antennal sensilla, has been linked to the communication challenges faced by social, but not solitary, insects. Recent evidence on patterns of asymmetry in insects outside of the Hymenoptera suggests that this explanation for antennal sensilla asymmetry may not be phylogenetically constrained. We explore this possibility by examining the distribution of antennal sensilla in three species of ants (Formicidae), the meat ant Iridomyrmex purpureus (Dolichoderinae), the green tree ant Oecophylla smaragdina (Formicinae) and the shield ant Meranoplus sp. (Myrmicinae) in which colony organisation is eusocial, and two species of nomiine bees, Mellitidia tomentifera and Reepenia bituberculata (Halictidae: Nomiinae), where colony organisation is not eusocial. Our results demonstrate that while there are differences in the left–right asymmetry of antennal sensilla basiconica in workers of the formicine ant I. purpureus, there is no consistent sensilla asymmetry across the five species. We find a negative correlation between antennal sensilla density and body size in R. bituberculata, which was not apparent in the other species. Our results contradict the suggestion that asymmetrical distribution of antennal sensilla is associated with the evolution of eusocial behaviour.

Social insects construct nests that protect their brood and food resources from both the physical environment and natural enemies. Stingless bees use plant-derived resins, mixed with wax to form propolis, in the construction of their nests, and these products can be effective sources of defense against natural enemies, including ants. However, it is not known whether this defense, in the form of deterring or repelling workers, derives from the physical properties or chemical compounds of these products. The nest entrance of Tetragonula carbonaria is constructed with propolis and Corymbia resins, and we ask whether nonvolatile chemicals present in these products act as a defense against ants. Our field experiments revealed that workers of Iridomyrmex mayri Forel were deterred from crossing a chemical barrier comprising nonvolatile, nonpolar (hexane) extracts of propolis and Corymbia tree resin. However, polar (ethanol) extracts did not have this effect. These data are the first to demonstrate that the chemical components alone of entrance propolis and resins can provide a nest-defense function against ants.

The Jarman-Bell principle seeks to explain why smaller herbivore species tend to select higher-quality forage (high protein and high fiber digestibility) than larger herbivore species. This principle may also provide insight into intraspecific differences in resource use in species with pronounced sexual size dimorphism. We examined the relationship between body mass and diet quality in a sexually dimorphic macropodid community comprising larger (17-55 kg) eastern and western gray kangaroos, Macropus giganteus and M. fuliginosus, and smaller (7-23 kg) red-necked and swamp wallabies, M. rufogriseus and Wallabia bicolor. We determined diet composition through microhistological analysis of fecal pellets, and then assessed diet quality by measuring available nitrogen and fiber (cellulose and hemicellulose) in the plants consumed. We predicted that the smaller species and smaller individuals within species would consume the highest-quality diets. The concentration of fiber consumed differed significantly among species; available nitrogen concentration did not. As predicted, the lowest-fiber diet was consumed by a wallaby (small species) and the highest-fiber diet was consumed by a kangaroo (large species). Contrary to predictions, we detected no sex-based differences in diet quality. However, large male red-necked wallabies consumed diets containing harder-to-digest fiber than small male red-necked wallabies. Body mass and diet type were related between and within species. However, body mass did not account for all differences in diet quality between species; swamp wallabies consumed less fiber than similarly sized red-necked wallabies. These differences are likely related to other adaptations that allow swamp wallabies to better tolerate tannin-rich browse-dominated diets.

Leaders in democratic societies emerge by dint of followers, but the traits that determine who those leaders are, and the underlying mechanisms maintaining leadership, remain largely unknown. Models suggest a link between leadership and knowledge is important for group decisions, with more informed individuals guiding the uninformed majority. In larval aggregations of the Australian steel blue sawfly, Perga affinis, some individuals consistently lead the group on foraging trips more frequently than expected by chance. We manipulated both social group composition and the environment to determine in what circumstances leaders were retained within the aggregation. Leaders only resumed guiding group movement when they were familiar with (i.e. had knowledge of) the environment, a role they undertook even among unknown conspecifics. However, knowledgeable followers did not lead naive aggregations. These results emphasize the importance of knowledge and prior experience in maintaining the leadership role within larval aggregations.

The article discusses the key role of the environment in the development of the evolutionary behaviors and gender inequality based on Charles Darwin's theory of sexual selection. It explains the behavior differences and gender gaps between men and women reflects the evolved pattern across the animal kingdom. It explores the role of the environment in shaping adaptive behaviors and stereotype of the daring promiscuous male against the cautious chaste female.

The use of prey-attracting allomones is likely to be an effective foraging strategy for sit-and-wait predators. Despite this, the production and efficacy of such allomones have rarely been documented. Previous investigations into the chemical composition of spider silk have revealed the presence of a number of potential allomone chemicals such as the amide putrescine, a foul-smelling organic compound. Putrescine is attractive to several terrestrial invertebrates, many of which are also typical prey species of spiders, but whether prey attraction is an underlying mechanism promoting its inclusion in web silk is currently untested. Here, we artificially increased the amount of putrescine in the web silk of female Argiope keyserlingi and assessed the resulting variation in prey interception of normal versus putrescine augmented webs under seminatural field conditions. We demonstrated that webs misted with a putrescine solution captured significantly more prey than webs misted with a control solution and also found differences in prey capture rates between individuals from different populations. This not only suggests that web-bound putrescine acts as a prey attracting allomone, but also that there is population level variation in the web-based foraging strategies of these spiders.

Social animals must communicate to define group membership and coordinate social organization. For social insects, communication is predominantly mediated through chemical signals, and as social complexity increases, so does the requirement for a greater diversity of signals. This relationship is particularly true for advanced eusocial insects, including ants, bees, and wasps, whose chemical communication systems have been well-characterized. However, we know surprisingly little about how these communication systems evolve during the transition between solitary and group living. Here, we demonstrate that the sensory systems associated with signal perception are evolutionarily labile. In particular, we show that differences in signal production and perception are tightly associated with changes in social behavior in halictid bees. Our results suggest that social species require a greater investment in communication than their solitary counterparts and that species that have reverted from eusociality to solitary living have repeatedly reduced investment in these potentially costly sensory perception systems.

Stomach bot flies (Calyptratae: Oestridae, Gasterophilinae) are obligate endoparasitoids of Proboscidea (i.e. elephants), Rhinocerotidae (i.e. rhinos) and Equidae (i.e. horses and zebras, etc.), with their larvae developing in the digestive tract of hosts with very strong host specificity. They represent an extremely unusual diversity among dipteran, or even insect parasites in general, and therefore provide significant insights into the evolution of parasitism. The phylogeny of stomach bot flies was reconstructed based on extensive mitochondrial genomic data for Cobboldia, Gyrostigma and six of the eight known species of Gasterophilus. The phylogenetic tree, i.e. {Cobboldia, [Gyrostigma, (Gasterophilus pecorum, (Gasterophilus intestinalis, (Gasterophilus haemorrhoidalis, Gasterophilus inermis)), (Gasterophilus nasalis, Gasterophilus nigricornis))]}, provides a strong evolutionary reference to infer several biological patterns for the first time for this group: (i) host shifts of stomach bot flies from elephants to rhinoceroses and then from rhinoceroses to equids; (ii) dispersal with their hosts from the Afrotropical region into the Palaearctic and Oriental regions; (iii) oviposition site, originally on the host head, and egg production positively correlated with distance from the mouth; (iv) attachment of third-instar larva originally in the stomach, with duodenal and large intestinal positions secondarily derived; and (v) guanine and cytosine enrichment of the mitogenome as an adaptation to larval life in the warm environment of the host digestive tract, combined with the need for a high evolutionary rate to cope with the fast evolution of their mammalian hosts.

Gregariousness is a common feature in aposematic insect prey and offers the additional benefit of enhancing the effectiveness of their toxic defences. Aggregations of the aposematic larvae of two species of leaf beetles, Paropsis atomaria and Paropsisterna variicollis, occur together on the same Eucalyptus trees over spring and summer. Conventionally, the colouration of these larvae is thought to provide aposematic protection against vertebrate predators, but supporting evidence is limited. We determine whether environmental preferences contribute to the heterospecific aggregations, and the potential costs for larvae of living in heterospecific aggregations. We surveyed natural aggregations of the larvae of both species in the field and recorded environmental variables of these aggregations. This revealed that heterospecific aggregations occurred more commonly at higher leaf temperatures, and in less visually conspicuous locations. Paropsis atomaria larvae were twice as likely to be found in heterospecific aggregations than Pa. variicollis. Next, we manipulated larval aggregations in the field to investigate the survival and gregarious behaviour of larvae in heterospecific aggregations. The gregarious behaviour of both species of larvae did not differ between heterospecific and monospecific aggregations. Further, the survival of larvae did not significantly differ between heterospecific and monospecific aggregations. We suggest that the preference for P. atomaria larvae to aggregate with Pa. variicollis at higher leaf temperature results in the observed heterospecific aggregations, with a potential benefit of lowerer parasitoidism rates for P. atomaria.

Parthenogenetic reproduction is taxonomically widespread and occurs through various cytological mechanisms, which have different impact on the genetic variation of the offspring. Extatosoma tiaratum is a facultatively parthenogenetic Australian insect (Phasmatodea), in which females oviposit continuously throughout their adult lifespan irrespective of mating. Fertilized eggs produce sons and daughters through sexual reproduction and unfertilized eggs produce female offspring via parthenogenesis. Here, we developed novel microsatellite markers for E. tiaratum and characterized them by genotyping individuals from a natural population. We then used the microsatellite markers to infer the cytological mechanism of parthenogenesis in this species. We found evidence suggesting parthenogenesis in E. tiaratum occurs through automixis with terminal fusion, resulting in substantial loss of microsatellite heterozygosity in the offspring. Loss of microsatellite heterozygosity may be associated with loss of heterozygosity in fitness related loci. The mechanism of parthenogenetic reproduction can therefore affect fitness outcomes and needs to be considered when comparing costs and benefits of sex versus parthenogenesis.

There is emerging interest in drawing insights from evolutionary biology to understand the nature of human leadership as a position within a social system. This perspective assumes that natural selection favors individuals who recognize leadership qualities that will benefit both leaders and followers. Physical stature, in particular, is frequently mentioned as a preferred human leadership trait. The present study documents and analyses the choice of leaders and its consequences for organization outcomes, using a model sporting system – the London 2012 Olympics and Paralympics. Team captains were no taller than their teammates, but they were consistently older, which had significant implications for team outcomes. The age of the captain was not correlated with team success, but it did influence team discipline: the frequency of serious infringements per game was negatively correlated with captain age. These results contradict the view that physical stature is a favored leadership trait, but nevertheless suggest that for human organizations, the search for leadership qualities might be profitably confined to those attributes that are likely to change with age and/or experience. Further, the evidence-based methodological approach highlights the value of examining directly the link between leadership attributes and real-life organization outcomes.

Most animals are under strong selection to avoid predation, and several strategies have evolved in response to this selection. The developmental change in colour patterns of toxin-protected chrysomeline larvae provides a system to investigate the potential costs and benefits of conspicuous coloration development in animals. Field experiments in which artificial, palatable prey of various colour patterns were presented to wild avian predators confirmed that warning colours alone are not sufficient to deter predation, but that the spatial distribution of yellow and black coloration may be key to conferring a warning signal.

Males can typically increase their lifetime reproductive success by mating with multiple females. However, recent studies across a broad range of species have demonstrated physiological constraints on male multiple mating. In this study, we investigate male mating capacity in Extatosoma tiaratum, a facultative parthenogenetic phasmatid. Sperm limitation is thought to be one factor favouring the evolution and maintenance of parthenogenetic reproduction, but studies on male mating ability in facultative parthenogenetic species are extremely rare. To explore whether male mating success varies with mating history, we provided males with weekly mating opportunities with different females throughout their lives. We then observed mating success, and the variation in ejaculate size and quality within each mating. We showed that most, but not all, males can mate multiply, however the amount of ejaculate produced is variable and depends upon male body mass and mating history.

Juvenile population density has profound effects on subsequent adult development, morphology and reproductive investment. Yet, little is known about how the juvenile social environment affects adult investment into chemical sexual signalling. Male gumleaf skeletonizer moths, Uraba lugens, facultatively increase investment into antennae (pheromone receiving structures) when reared at low juvenile population densities, but whether there is comparable adjustment by females into pheromone investment is not known. We investigate how juvenile population density influences the ‘calling' (pheromone-releasing) behaviour of females and the attractiveness of their pheromones. Female U. lugens adjust their calling behaviour in response to socio-sexual cues: adult females reared in high juvenile population densities called earlier and for longer than those from low juvenile densities. Juvenile density also affected female pheromonal attractiveness: Y-maze olfactometer assays revealed that males prefer pheromones produced by females reared at high juvenile densities. This strategic investment in calling behaviour by females, based on juvenile cues that anticipate the future socio-sexual environment, likely reflects a response to avoid mating failure through competition with neighbouring signallers.

The elaborate bipectinate antennae of male moths are thought to increase their sensitivity to female sex pheromones, and so should be favoured by selection. Yet simple filamentous antennae are the most common structure among moths. The stereotypic arrangements of scales on the surface of antennae may resolve this paradox. We use computational fluid dynamics techniques to model how scales on the filamentous antennae of moths affect the passage of different particles in the airflow across the flagellum in both small and large moths. We found that the scales provide an effective solution to improve the efficacy of filamentous antennae, by increasing the concentration of nanoparticles, which resemble pheromones, around the antennae. The smaller moths have a greater increase in antennal efficiency than larger moths. The scales also divert microparticles, which resemble dust, away from the antennal surface, thereby reducing contamination. The positive correlations between antennal scale angles and sensilla number across Heliozelidae moths are consistent with the predictions of our model.

Intersexual agonistic encounters prior to mating are thought to result from the ‘spillover’ of the advantages of a voracious personality within a foraging context that is maladaptive in a mating context. We tested this idea by examining the repeatability and cross-context consistency of aggressive behaviours associated with foraging and mating in the raft spider, Dolomedes fimbriatus, in which some, highly voracious females reportedly kill approaching males and thus remain unmated. We failed to find support for a maladaptive spillover of voracious female personality. While females exhibited consistent interindividual differences in voracity towards prey, voracity did not correlate with female aggressiveness towards males. Instead, we show that female D. fimbriatus adjusted their tendency to attack courting males according to their size relative to the male. Females commonly attacked males during or after copulation, but sexual cannibalism depended on relative mate size difference, with mating success tending to be compromised in females with lower body weight.

Specialist species show stronger resource selection, narrower niches and lower niche overlap than generalist species. We examined ecological specialisation with respect to habitat selection in a macropodid community comprising the western grey kangaroo Macropus fuliginosus, red-necked wallaby M. rufogriseus and swamp wallaby Wallabia bicolor in the Grampians National Park, Victoria, Australia. We used radio tracking to quantify habitat selection. We predicted that because the fitness benefits of generalisation and specialisation differ, there would be a mix of generalised and specialised species in our community. As all three macropodid species show marked sexual dimorphism, we also expected that they would show sex-based specialisation. Finally, because many large herbivores select different habitats for foraging and resting, we predicted that our species would specialise on a subset of their overall selected habitat based on activity period (diurnal or nocturnal). All three species specialised on the available resources to some degree. Western grey kangaroos were specialists, at least during the active period. Niche data for the two wallaby species were harder to interpret so we could not determine their degree of specialisation. Within species, we found no evidence of sex-based specialisation. However, we found clear evidence of specialisation by activity period in western grey kangaroos and red-necked wallabies, but not in swamp wallabies. The strength of behavioural decisions made during the active period in influencing specialisation points to the likelihood that bottom-up processes regulate this community.

Pheromones, arguably the most ubiquitous mode of animal communication, are determined by both genetic and environmental factors. Recent evidence suggests that diet may be an important determinant of pheromone variation, which may both enhance and reduce the reliability of the chemical signal. We investigated experimentally the impact of population origin and diet on chemical signals used in mate assessment by monogynous males of the golden-banded orb web spider, Argiope trifasciata. Initial mate preference experiments revealed environmentally determined fine scaling of male mate choice: shortly after their introduction into the laboratory, male spiders preferred females from either their own or a nearby population rather than females from a distant population, suggesting that male choice is driven by phenotype matching, ensuring correct species identity. However, when diet was controlled, males preferred females originating from a distant rather than the same population, allowing males to choose a mate with the most potential genetic benefits. A second set of experiments clearly demonstrated that diet affected the chemical compounds on the surface of the silk threads produced by females, and that males preferred females that had experienced a similar diet. We suggest that phenotype matching strongly influences broad-scale male mating preferences, but it remains to be seen how a combination of genetic and environmental (e.g. dietary) factors influence the relative abundance of these, and perhaps other, mate choice-relevant, silk-bound chemical cues. (C) 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Several species of stick insects sway from side to side when blown by wind. Although anecdotal evidence suggests this is a camouflage strategy to resemble wind-blown vegetation, this behavior has never been experimentally investigated. We evaluated the responses of female Macleay’s Spectre (Extatosoma tiaratum) to wind cues and quantified the degree of conspicuousness of the insect against a background of natural wind-blown plants. Wind alone is sufficient to initiate but not maintain swaying behavior. Sway frequency declined over time in all trials, but the number of sways was significantly higher in variable wind conditions compared with constant wind conditions. This suggests the insects pay attention to environmental cues and adjust their behavior accordingly. Consistent with this view, in trials involving plants in which the insects did not sway, plant motion was significantly stronger than at times when insects were observed to sway. The movement of insects at these times was indeed consistent in the frequency domain with the movement of wind-blown plants. This study provides evidence that the swaying movement of E. tiaratum is quantitatively similar to that of wind-blown plants. Further studies will be required to identify functional benefits of this behavior and whether it represents a form of motion crypsis, motion masquerade, or a combination of the two.