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Gender inequality and sexist behaviour is prevalent in almost all workplaces and rampant in online environments. Although there is much research dedicated to understanding sexist behaviour, we have almost no insight into what triggers this behaviour and the individuals that initiate it. Although social constructionist theory argues that sexism is a response towards women entering a male dominated arena, this perspective doesn't explain why only a subset of males behave in this way. We argue that a clearer understanding of sexist behaviour can be gained through an evolutionary perspective that considers evolved differences in intra-sexual competition. We hypothesised that female-initiated disruption of a male hierarchy incites hostile behaviour from poor performing males who stand to lose the most status. To test this hypothesis, we used an online first-person shooter video game that removes signals of dominance but provides information on gender, individual performance, and skill. We show that lower-skilled players were more hostile towards a female-voiced teammate, especially when performing poorly. In contrast, lower-skilled players behaved submissively towards a male-voiced player in the identical scenario. This difference in gender-directed behaviour became more extreme with poorer focal-player performance. We suggest that low-status males increase female-directed hostility to minimize the loss of status as a consequence of hierarchical reconfiguration resulting from the entrance of a woman into the competitive arena. Higher-skilled players, in contrast, were more positive towards a female relative to a male teammate. As higher-skilled players have less to fear from hierarchical reorganization, we argue that these males behave more positively in an attempt to support and garner a female player's attention. Our results provide the clearest picture of inter-sexual competition to date, highlighting the importance of considering an evolutionary perspective when exploring the factors that affect male hostility towards women.

The peacock spider, Maratus volans, has one of the most elaborate courtship displays in arthropods. Using regular and high-speed video segments captured in the lab, we provide detailed descriptions of complete male courtship dances. As research on jumping spiders has demonstrated that males of some species produce vibrations concurrently with visual displays, we also used laser vibrometry to uncover such elements for this species. Our recordings reveal and describe for the first time, that M. volans males use vibratory signals in addition to complex body ornaments and motion displays. The peacock spider and other closely related species are outstanding study organisms for testing hypotheses about the evolution and functional significance of complex displays, thus, this descriptive study establishes a new model system for behavioral ecology, one that certainly stands to make important contributions to the field.

Our understanding of sexual selection is advancing with new technologies that tag individuals or their sperm, revealing how females use post‐copulatory processes to discriminate between competing mates. Many tagging methods have been devised primarily for model insect organisms like Drosophila or Gryllidae. Developing such novel methods, however, is expensive and requires intensive investment. In this experiment, we trial the use of Rhodamine B (RhB) and Rhodamine 110 (Rh110) in a small arachnid, the bulb mite Rhizoglyphus echinopus, for pre‐ and post‐copulatory observations as it is a relatively inexpensive and simple way to tag individuals and their ejaculate proteins. First, we tested whether RhB and Rh110 applied to food can be used as a tagging method to track and distinguish between individuals. Second, we explored whether Rhodamine applied in this way can be used to track sperm transfer. We found that both tagging probes worked well in tagging individuals and that we were able to distinguish between individuals using both LED and fluorescent microscopy. We also found that Rhodamine degraded rapidly in the animals, likely due to their fast metabolism. Due to the rapid degradation, we observed variable results in the sperm transfer trials. We suggest multiple uses for Rhodamine and highlight other invertebrates where this method may come into use for the study of sexual selection. We trial the use of Rhodamine, for the first time in arachnids. We first trial the method for behavioural ecology and evolution trials to track the individuals within large population sizes. Furthermore, we trial this method for post‐copulatory studies that investigate sperm competition and female cryptic choice.

Selection has led to the evolution of a variety of different mating strategies, each adapted to different competitive challenges. But what happens if the competitive challenges depend on the social environment? Here we discuss and review examples of socially cued anticipatory plasticity: irreversible developmental tactics in which resource allocation during the juvenile stage is altered to develop an appropriate phenotype for the competitive or mate choice environment that an individual encounters when mature. There are numerous theoretical and empirical examinations of the role of the social environment on the strength and direction of selection. However, only a handful of empirical studies examine how the social environment affects juvenile allocation and whether such tactics are adaptive. The goal of this review is to synthesize current knowledge about socially cued anticipatory plasticity, including the sensory modalities that individuals use to predict the adult competitive and mating environment. We then outline the various factors that are necessary for the evolution of socially cued anticipatory plasticity and discuss how this can affect phenotypic evolution. We conclude by suggesting some directions that future studies should take in order to understand how social variation can alter selection and the evolution of development.

Our understanding of animal contests and the factors that affect contest dynamics and decisions stems from a long and prosperous collaboration between empiricists and theoreticians. Over the last two decades, however, theoretical predictions regarding the factors that affect individual decisions before, during and after a contest are becoming increasingly difficult to test empirically. Extremely large sample sizes are necessary to experimentally test the nuanced theoretical assumptions surrounding how information is used by animals during a contest, how context changes the information used, and how individuals change behaviour as a result of both the information available and the context in which the information is acquired. In this review, we discuss how the investigation of contests in humans through the collaboration of biologists and psychologists may advance contest theory and dynamics in general. We argue that a long and productive history exploring human behaviour and psychology combined with technological advancements provide a unique opportunity to manipulate human perception during contests and collect unbiased data, allowing more targeted examinations of particular aspects of contest theory (e.g. winner/loser effects, information use as a function of age). We hope that our perspective provides the impetus for many future collaborations between biologists and psychologists.

Individual quality has been measured as a variety of different traits and in several different contexts. However, the implications of such measurements in terms of overall fitness are less straightforward than has generally been appreciated. Here we outline some key issues in this regard that have yet to be addressed. Specifically, we consider the importance of both variation in selection on individual and multivariate suites of traits, and of context-specific plasticity in allocation strategies. We argue that an explicit life-history perspective is crucial for understanding variation in quality, as both the strength and direction of selection and an individual's response to it can vary within a breeding season. Hence, ‘quality’ is not a static characteristic that can be measured by taking longitudinal measures of single traits across a population, but rather a dynamic, multivariate suite of traits that is dependent not only on the selective context, but also on the nature and intensity of selection operating at any given time. We highlight these points by considering recent research on selection and plasticity.

There are substantive problems associated with invasive species, including threats to endemic organisms and biodiversity. Understanding the mechanisms driving invasions is thus critical. Variable extended phenotypes may enable animals to invade into novel environments. We explored here the proposition that silk variability is a facilitator of invasive success for the highly invasive Australian house spider, Badumna longinqua . We compared the physico-chemical and mechanical properties and underlying gene expressions of its major ampullate (MA) silk between a native Sydney population and an invasive counterpart from Montevideo, Uruguay. We found that while differential gene expressions might explain the differences in silk amino acid compositions and protein nanostructures, we did not find any significant differences in silk mechanical properties across the populations. Our results accordingly suggest that B . longinqua ’s silk remains functionally robust despite underlying physico-chemical and genetic variability as the spider expands its range across continents. They also imply that a combination of silk physico-chemical plasticity combined with mechanical robustness might contribute more broadly to spider invasibilities.

A long-standing goal for biologists has been to understand how female preferences operate in systems where males have evolved numerous sexually selected traits. Jumping spiders of the Maratus genus are exceptionally sexually dimorphic in appearance and signalling behaviour. Presumably, strong sexual selection by females has played an important role in the evolution of complex signals displayed by males of this group; however, this has not yet been demonstrated. In fact, despite apparent widespread examples of sexual selection in nature, empirical evidence is relatively sparse, especially for species employing multiple modalities for intersexual communication. In order to elucidate whether female preference can explain the evolution of multi-modal signalling traits, we ran a series of mating trials using Maratus volans. We used video recordings and laser vibrometry to characterize, quantify and examine which male courtship traits predict various metrics of mating success. We found evidence for strong sexual selection on males in this system, with success contingent upon a combination of visual and vibratory displays. Additionally, independently produced, yet correlated suites of multi-modal male signals are linked to other aspects of female peacock spider behaviour. Lastly, our data provide some support for both the redundant signal and multiple messages hypotheses for the evolution of multi-modal signalling.

The juvenile environment provides numerous cues of the intensity of competition and the availability of mates in the near environment. As research demonstrates that the developing individuals can use these cues to alter their developmental trajectories, and therefore, adult phenotypes, we examined whether social cues available during development can affect the expression and the preference of sexually selected traits. To examine this, we used the Australian black field cricket (Telogryllus commodus), a species where condition at maturity is known to affect both male calling effort and female choice. We mimicked different social environments by rearing juveniles in two different densities crossed with three different calling environments. We demonstrate that the social environment affected female response speed but not preference, and male age‐specific calling effort (especially the rate of senescence in calling effort) but not the structural/temporal parameters of calls. These results demonstrate that the social environment can introduce variation in sexually selected traits by modifying the behavioral components of male production and female choice, suggesting that the social environment may be an overlooked source of phenotypic variation. We discuss the plasticity of trait expression and preference in reference to estimations of male quality and the concept of condition dependence. We demonstrate that the social environment introduces variation in sexually selected traits by modifying the behavioural components of male production and female choice. We suggest that the social environment is an overlooked source of phenotypic variation and discuss the plasticity of trait expression and preference in reference to estimations of male quality and the concept of condition dependence.