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Deimatic behaviours, also referred to as startle behaviours, are used against predators and rivals. Although many are spectacular, their proximate and ultimate causes remain unclear. In this review we aim to synthesise what is known about deimatic behaviour and identify knowledge gaps. We propose a working hypothesis for deimatic behaviour, and discuss the available evidence for the evolution, ontogeny, causation, and survival value of deimatic behaviour using Tinbergen's Four Questions as a framework. Our overarching aim is to direct future research by suggesting ways to address the most pressing questions in this field. peerReviewed

The COVID-19 pandemic and interventions addressing it raise important questions about human mobility that have geopolitical implications. This forum uses mobility and immobility during the pandemic as lenses onto the ways that routinised state power reacts to acute uncertainties, as well as how these reactions impact politics and societies. Specifically, we propose the concept of “shock mobility” as migratory routines radically reconfigured: emergency flights from epicentres, mass repatriations, lockdowns, quarantines. Patterns of shock mobility and immobility are not new categories of movement, but rather are significant alterations to the timing, duration, intensity, and relations among existing movements. Many of these alterations have been induced by governments’ reactions to the pandemic in both migrant-sending and receiving contexts, which can be especially consequential for migrants in and from the Global South. Our interventions explore these processes by highlighting experiences of Afghans and Kurds along Iran’s borders, Western Africans in Europe, Filipino workers, irregular Bangladeshis in Qatar, Central Americans travelling northwards via Mexico, and rural-urban migrants in India. In total, we argue that tracing shocks’ dynamics in a comparative manner provides an analytical means for assessing the long-term implications of the pandemic, building theories about how and why any particular post-crisis world emerges as it does, and paving the way for future empirical work.

Existing studies demonstrate that threat perceptions matter for immigration attitudes. However, while these perceptions are potentially sensitive to information about immigrants’ impacts, questions remain about whether inserting such information into public debates changes attitudes and policy preferences—especially on polarizing issues like immigration. Moreover, few studies have considered messages featuring the type of nonphotorealistic visual elements that increasingly appear in media. Using a survey experiment fielded in the United Kingdom, we examined whether evidence about European Union immigrants’ modestly positive economic impacts on the United Kingdom—presented either as text, with visualizations, or as an animated film—changed immigration attitudes and policy preferences. Although visual elements did not have an effect over and above text, all the informational treatments moved attitudes and preferences in positive directions, even among Leave voters. Our study brings together research on immigration public opinion and visual media and has implications for policymaking and journalism practice.

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How do governments visually communicate policies, and what does this reveal about actors’ political objectives? Governments strategically narrate their priorities, yet few studies examine this process through visual modes. We contribute to theoretical and empirical understanding in policy studies by focusing on the UK government’s COVID-19 response through its daily press briefings during the first wave of 2020. Combining quantitative changepoint and content analysis with qualitative discourse analysis, we examine all 79 sets of slides when briefings occurred. We identify a reactive phase focused on communicating knowledge about the pandemic in a boundedly rational manner, and a proactive phase that created new policy-based narratives of the pandemic. Besides contributing to emerging pandemic-related policy scholarship, we argue that conceiving these visualizations as visual narrative assemblages is relevant more broadly because it shifts attention to the interaction and interdependence of multiple visualizations as they enable policymakers to perform their authority to govern.

Social media have become conduits through which audiences can challenge elites in media and politics. Recent updates to cascading activation, originally developed to explain how frames flowing from powerful figures gain public dominance, give greater theoretical scope for audiences to exert influence. Yet empirical understanding of how and in what circumstances this happens with respect to agenda-setting - another core media effect - is not well-developed, especially given the affordances of digital technologies. We address this gap by connecting theorization on cascades to developments in intermedia agenda-setting. Specifically, we analyze the dynamics surrounding the perceived reluctance by ARD-aktuell, the newsroom of Germany's public broadcasting consortium, to use its prime-time broadcast "Tagesschau" to report the arrest of a refugee accused of murdering a German woman in December 2016. By presenting finely grained timelines linking content analysis of 5,409 Facebook comments with Tagesschau editorial responses and parallel media coverage of this event, we contribute further conditions under which audience-informed cascades may occur: notably, when publicly funded news organizations are involved, and the issue at stake invokes both domestic and international aspects which sustain disagreement.

As larger and more varied datasets on socially and political relevant issues have become available to researchers, computational methods that aim to make sense of them have also proliferated. In response, social scientists need to critically reflect on and take stock of the opportunities and challenges presented by these shifts. This chapter draws upon on a series of projects that involved collecting, analysing, and communicating results from a large corpus of British newspaper texts about migration, asylum-seekers, and refugees spanning 1985-2015. By reporting the choices I made during these steps, as well as the contexts in which they happened, I aim to draw out both theoretical and practical lessons for researchers wanting to use computational approaches to media data involving political topics like migration—particularly, but not exclusively, from linguistic perspectives.

Researchers studying international organizations have access to growing and varied archives due to digitization efforts. While developments in computational methods confer efficiency gains for examining these materials at scale, they raise concerns about their validity when applied to interpretive tasks in historical settings. In response, we present a general and flexible workflow that uses simple computational techniques from linguistics to enhance archival researchers’ interpretive skills and sensitivity to historical contexts. These techniques also identify patterns that can serve as evidence of causal mechanisms when embedded within strong research designs and theoretical expectations. Then, we demonstrate our mixed-method approach by applying it to a dataset of International Labour Organization’s (ILO) annual reports spanning ninety-three years. Examining the ILO's engagement with refugees as described in these documents, we identify key moments during which refugees have been particularly salient for this organization, and the emergence of new issues on its high-level policy agenda.

This chapter looks at the production of data visualizations (dataviz) in newsrooms and audiences’ everyday engagements with them.

Background:Advance directives are legal documents that include living wills and durable health care power of attorney documents. They are critical components of care for seriously ill patients which are designed to be implemented when a patient is terminally ill and incapacitated. We sought to evaluate potential reasons for why advance directives were not appropriately implemented, by reviewing the electronic health record (EHR) in patients with terminal cancer.Methods:A retrospective analysis of the EHR of 500 cancer patients from 1/1/2013 to 12/31/2016 was performed. Data points were manually collected and entered in a central database.Results:Of the 500 patients, 160 (32%) had an advance directive (AD). The most common clinical terminology used by physicians indicating a terminal diagnosis was progressive (36.6%) and palliative (31%). The most common clinical terminology indicating incapacity was altered mental status (25.6%), and not oriented (14%). 34 (6.8%) patients met all criteria of having a terminal diagnosis, a documented AD, and were deemed incapacitated. Of these patients who met all of these data points, their ADs were implemented on average 1.7 days (SD: 4.4 days) after which they should have been. This resulted in a total of 58 days of additional care provided.Discussion:This study provided insight on to how ADs are managed in day to day practice in the hospital. From our analysis it appears that physicians are able to identify when a patient is terminal, however, it is typically later than it should have been recognized. Further studies should be performed focusing on harnessing the power of the EHR and providing physicians formative and evaluative feedback of practice patterns to ensure that ADs are honored when appropriate.

Understanding the role of traits in dispersal is necessary to improve our knowledge of historical biogeography, community assembly processes and predictions of species' future movements. Here we aimed to determine the relationship between three traits (coastal distribution, body size, position on the fast/slow life history continuum) and past dispersal probability on an evolutionary timescale in chameleons (Chamaeleonidae). Using species' distribution data we identified the nine most important biogeographic regions for all included chameleons (181/217 species). We compiled life history trait data and used phylogenetic factor analysis to infer independent body size and fast/slow life history trait axes. Finally, we tested whether traits and trait combinations related to biogeographic dispersal success in the past, using trait-dependent biogeographic models. All three traits were associated with past biogeographical movements. Lineages having coastal distributions and those with large bodies had higher dispersal probabilities. Interestingly, chameleons with either a very fast or very slow life history were more successful dispersers than species with an intermediate strategy. Together, the three traits - coastal, large-bodied and extreme life history - form a dispersal syndrome. Traits have played an important role in the biogeographic history of chameleons. While only fast traits have been linked to present-day invasion success in reptiles, both extremes of the life history spectrum were likely advantageous for dispersal and establishment during past biogeographic movements. Fast-living species may be less susceptible to stochastic extinction in the first phases of a colonization (due to rapid population growth), and slow-living species may be less vulnerable to environmental stochasticity (due to low demographic variability). Our results call for broader analyses testing the general influence of life history strategy in biogeographic dispersal success, which would help explain species distribution patterns on Earth.

Biological phenotypes are products of complex evolutionary processes in which selective forces influence multiple biological trait measurements in unknown ways. Phylogenetic factor analysis disentangles these relationships across the evolutionary history of a group of organisms. Scientists seeking to employ this modeling framework confront numerous modeling and implementation decisions, the details of which pose computational and replicability challenges. General and impactful community employment requires a data scientific analysis plan that balances flexibility, speed and ease of use, while minimizing model and algorithm tuning. Even in the presence of non-trivial phylogenetic model constraints, we show that one may analytically address latent factor uncertainty in a way that (a) aids model flexibility, (b) accelerates computation (by as much as 500-fold) and (c) decreases required tuning. We further present practical guidance on inference and modeling decisions as well as diagnosing and solving common problems in these analyses. We codify this analysis plan in an automated pipeline that distills the potentially overwhelming array of modeling decisions into a small handful of (typically binary) choices. We demonstrate the utility of these methods and analysis plan in four real-world problems of varying scales., 27 pages, 7 figures, 1 table

Here, we investigate the camouflage consequences of animal orientation behaviour. Shadows can be a conspicuous cue to the presence of prey. For bilaterally symmetrical animals, light field modelling indicates that camouflage will be improved when an animal orients its longitudinal axis directly towards or away from the sun, because the appearance of shadows is minimized. We test this prediction with a field predation experiment, in which wild birds hunt for artificial camouflaged prey oriented with the longitudinal axis either parallel or perpendicular to the sun. We find that prey oriented parallel to the sun are 3.93 times more likely to survive than prey oriented perpendicular to the sun. This result demonstrates the strong orientation dependence of camouflage. Given the dramatic difference in survival of prey with different orientations, we suggest that camouflage should be investigated as an important determinant of the positional behaviour of animals.

Bester (2020) correctly calls attention to two different meanings of the concept of benefit commonly used in clinical medicine, one objective and determined by clinicians, and the other, subjective...

Caudal autotomy is a dramatic antipredator adaptation where prey shed their tail in order to escape capture by a predator. The mechanism underlying the effectiveness of caudal autotomy as a pre‐capture defense has not been thoroughly investigated. We tested two nonexclusive hypotheses, that caudal autotomy works by providing the predator with a “consolation prize” that makes it break off the hunt to consume the shed tail, and the deflection hypothesis, where the autotomy event directs predator attacks to the autotomized tail enabling prey escape. Our experiment utilized domestic dogs Canis familiaris as model predator engaged to chase a snake‐like stimulus with a detachable tail. The tail was manipulated to vary in length (long versus short) and conspicuousness (green versus blue), with the prediction that dog attacks on the tail should increase with length under the consolation‐prize hypothesis and conspicuous color under the deflection hypothesis. The tail was attacked on 35% of trials, supporting the potential for pre‐capture autotomy to offer antipredator benefits. Dogs were attracted to the tail when it was conspicuously colored, but not when it was longer. This supports the idea that deflection of predator attacks through visual effects is the prime antipredator mechanism underlying the effectiveness of caudal autotomy as opposed to provision of a consolation prize meal., In an experiment on domestic dogs chasing model prey, we found that attacks were directed to an autotomized body parts when it was conspicuously colored but not when it was longer. This supports the hypothesis that autotomy is principally effective because of perceptual deflection of attacks rather than because it offers predators a “consolation prize” meal.

Sexual selection produces extravagant male traits, such as colorful ornaments, via female mate choice. More rarely, in mating systems in which males allocate mating effort between multiple females, female ornaments may evolve via male mate choice. Females of many anthropoid primates exhibit ornaments that indicate intraindividual cyclical fertility, but which have also been proposed to function as interindividual quality signals. Rhesus macaque females are one such species, exhibiting cyclical facial color variation that indicates ovulatory status, but in which the function of interindividual variation is unknown. We collected digital images of the faces of 32 rhesus macaque adult females. We assessed mating rates, and consortship by males, according to female face coloration. We also assessed whether female coloration was linked to physical (skinfold fat, body mass index) or physiological (fecal glucocorticoid metabolite [fGCM], urinary C-peptide concentrations) condition. We found that redder-faced females were mated more frequently, and consorted for longer periods by top-ranked males. Redder females had higher fGCM concentrations, perhaps related to their increased mating activity and consequent energy mobilization, and blood flow. Prior analyses have shown that female facial redness is a heritable trait, and that redder-faced females have higher annual fecundity, while other evidence suggests that color expression is likely to be a signal rather than a cue. Collectively, the available evidence suggests that female coloration has evolved at least in part via male mate choice. Its evolution as a sexually selected ornament attractive to males is probably attributable to the high female reproductive synchrony found in this species.

I review ethical and legal challenges for end of life (EOL) care in dementia. Is access to hospice care for dementia patients impacted by Medicare’s terminal prognosis requirement? Are dementia-specific advance directives warranted? How does state legislation affect dementia patients’ EOL options? Should dementia patients’ be able to refuse orally ingested food and fluids by advance directive? The difficulty of predicting time to death in dementia inhibits access to Medicare hospice benefits. Efforts have been made to create dementia-specific advance directives. Advance refusal of artificial nutrition and hydration are common, but the issue of oral ingestion of food and fluids by dementia patients remains controversial. Medicare’s hospice benefit should be made more accessible to dementia patients. State advance directive threshold definitions should be broadened to include dementia, and capacitated persons who refuse in advance orally ingested food and fluids should have their choices honored.

Discriminating between conspecifics and heterospecifics potentially challenging for closely related sympatric species. The guenons, a recent primate radiation, exhibit high degrees of sympatry and form multi-species groups in which hybridization is possible but rare in most populations. Guenons have species-specific colorful face patterns hypothesized to function in species discrimination. Here, we apply a novel machine learning approach to identify the face regions most essential for correct species classification across fifteen guenon species. We then demonstrate the validity of these computational results using experiments with live guenons, showing that facial traits identified as critical for accurate classification do indeed influence selective attention toward con- and heterospecific faces. Our results suggest variability among guenon species in reliance on single-trait-based versus holistic facial characteristics when discriminating between species, and differences in behavioral responses to faces can be linked to whether discrimination is based on a single trait or whole-face pattern. Our study supports the hypothesis that guenon face patterns function to promote species discrimination and provides novel insights into the relationship between species interactions and phenotypic diversity.

Comparative biologists are often interested in inferring covariation between multiple biological traits sampled across numerous related taxa. To properly study these relationships, we must control for the shared evolutionary history of the taxa to avoid spurious inference. Existing control techniques almost universally scale poorly as the number of taxa increases. An additional challenge arises as obtaining a full suite of measurements becomes increasingly difficult with increasing taxa. This typically necessitates data imputation or integration that further exacerbates scalability. We propose an inference technique that integrates out missing measurements analytically and scales linearly with the number of taxa by using a post-order traversal algorithm under a multivariate Brownian diffusion (MBD) model to characterize trait evolution. We further exploit this technique to extend the MBD model to account for sampling error or non-heritable residual variance. We test these methods to examine mammalian life history traits, prokaryotic genomic and phenotypic traits, and HIV infection traits. We find computational efficiency increases that top two orders-of-magnitude over current best practices. While we focus on the utility of this algorithm in phylogenetic comparative methods, our approach generalizes to solve long-standing challenges in computing the likelihood for matrix-normal and multivariate normal distributions with missing data at scale., Comment: 29 pages, 7 figures, 2 tables, 3 supplementary sections

The dorsal surfaces of many taxonomic groups often feature repetitive pattern elements consisting of stripes, spots, or bands. Here, we investigate how distinct categories of camouflage pattern work by relating them to ecological and behavioral traits in 439 species of gecko. We use phylogenetic comparative methods to test outstanding hypotheses based on camouflage theory and research in other taxa. We found that bands are associated with nocturnal activity, suggesting bands provide effective camouflage for motionless geckos resting in refugia during the day. A predicted association between stripes and diurnal activity was not supported, suggesting that stripes do not work via dazzle camouflage mechanisms in geckos. This, along with a lack of support for our prediction that plain patterning should be associated with open habitats, suggests that similar camouflage patterns do not work in consistent ways across taxa. We also found that plain and striped lineages frequently switched between using open or closed habitats, whereas spotted lineages rarely transitioned. This suggests that pattern categories differ in how specialized or generalized their camouflage is. This result has ramifications for theory on how camouflage compromises to background heterogeneity and how camouflage pattern might influence evolutionary trajectories.

When and how does press coverage maintain independence from governments’ preferred language? Leading scholarship argues that elites shape media content, especially in foreign affairs settings where journalists rely on official sources. But do media push back in domestic policy contexts? Focusing on immigration in Britain, we find press coverage exhibits signs of autonomy that rely on the state’s administrative branches. Our evidence comes from automated linguistic analysis of 190,000 items of migration coverage in nineteen national British newspapers from 2006 to 2015, and press releases published by the U.K. Home Office between 2010 and 2015. We show that the press increasingly portrayed immigration in terms of its scale. Then, by comparing the dynamics of a key government policy—lowering “net migration”—in press and Home Office rhetoric, we illustrate the limits of the government to insert its desired language into the press. Finally, we argue routine press interactions with the nonpolitical Office for National Statistics enabled coverage that diverged from politicians’ preferred lines. Our study contributes to press-state theory by providing evidence of media semiautonomy in a domestic policy arena, and highlighting the often-overlooked role of routine, bureaucratic procedure in supporting that autonomy.

This research was supported by the National Science Foundation EPSCoR Grant No.IIA-1301765.

Civil society organisations increasingly mediate the creation and exchange of evidence in their activities with policy-makers and practitioners. This article extends knowledge on evidence in policy-making settings to civil society contexts. As an exploratory and qualitative study, it shows how nine UK-based organisations working on issues including migration and social welfare hold different perceptions of evidence and its usefulness. A range of related factors involving individuals, organisations, sectors, and issue areas emerge as contingent contributors to these variations. The results suggest that researchers and practitioners seeking to engage with civil society using evidence should consider context-specific values, skills, motivations, and timeliness.

This chapter addresses how research and public debate about migration interact with and inform each other, focusing on public perceptions and media coverage as important aspects. Factors including generalized public innumeracy about migration levels, effects of emotions on perceptions, and variation in the perceived credibility of different messengers make communicating information— of which research evidence is an important type—a complex process with multiple points of potential resistance. Meanwhile, the demands and expectations of public users and policy-makers can influence how research happens and the types of questions that are seen to be more meaningful. These interrelationships exist within wider social, political, and economic contexts that, in certain circumstances, are likely to favour some outcomes over others. In total, the chapter argues that the pathway from generating research evidence to impacting public debates is not only uncertain, it is also more complex than is often presumed. Research on migration often aims to influence not only relatively specialized research communities, but also broader society including political institutions, policy processes, and media and public debates. Whether motivated by the intrinsic value of relating their work to the wider world, or prodded by shifting financial and professional incentives, academic researchers increasingly find themselves being asked to demonstrate how their work has impact beyond universities—especially when that research is publicly funded. Yet, defining and generating that impact is often elusive. Public debate and major policy decisions often seem to fly in the face of the evidence base accumulated by researchers in the academy, civil society, and even in government agencies themselves. Despite escalating pressure to produce impactful research, evidence-based public debate seems as far off as ever—particularly on the issue of immigration, where public discussion is often polarized, emotive, and based on perceptions rather than reality (Duffy 2014). In this chapter, we explore the relationships between research and public debate, two aspects of the tripartite model proposed in the Introduction to this volume. We argue that the idea of ‘research impact’ is often based on a naive model of one-way effects that does not reflect the multifaceted relationships between research and elements of public debate. The pathway from research evidence to public debate is not only uncertain, it is also inevitably bidirectional: media and public discussions affect research as well as being affected by it. As academics aim to have impact on public debate, they should acknowledge even further how their research—comprising the questions they ask, the methods they employ, and the modes and venues in which they present their (p.51) findings—relates to the contours of public debate. Therefore, despite growing expectations that research can and should influence public debate, the implicit model of impact underlying such expectations is misleading and simplistic.

The goal of this paper is to present a methodology for professional evaluation, comparison and selection of alternatives in conservation planning and related areas. Our decision methodology is based on soft computing and consistent with observable properties of human reasoning. Main topics that we cover include the presentation of the LSP (Logic Scoring of Preference) decision method, the analysis of benefits that soft computing graded logic provides in comparison to traditional oversimplified additive weighted scoring models, and a detailed presentation of the Upper Neuse Clean Water Initiative in North Carolina, which is a real-life decision project in landscape planning and strategic conservation, based on our proposed methodology. In addition, we also present results of using decision support software tools that are necessary for the development and use of decision criteria. Our methodology and results are applicable in a wide variety of areas, including ecology, open space management, urban planning, geographic information systems, and decision making in agriculture. Keywords LSP method Strategic conservation Suitability analysis Multi-criteria decision making Graded logic Simple additive scoring Landscape planning Water quality protection GIS

Public opposition to immigration in Britain reflects perceptions of immigrants that focus disproportionately on “illegal” immigration and asylum seekers, rather than more numerous workers, students, and family members. This study examines coverage of immigration in the British national press, to see whether press portrayals of migrants provide a basis for these images of immigration underlying public attitudes. We use corpus linguistic methods to analyze 43 million words of news from 2010 to 2012. Among other findings, we show that press portrayals match public perceptions of migrants, with “illegal immigrants” and “failed asylum seekers” as predominant depictions in broadsheet and tabloid newspapers.

A consensus exists among academics that cost-effective land preservation should involve both benefits and costs. In reality, the vast majority of programs do a poor job at being cost-effective. Few studies have examined why conservation professionals have failed to adopt cost-effective approaches. This study reports on a survey conducted with conservation professionals associated with the Maryland Agricultural Land Preservation Foundation, a leading program in the United States where county program administrators have experience with both traditional benefit targeting approaches and optimization approaches. Results show that conservation professionals place lower importance on cost-effectiveness than transparency and fairness, which are the most critical elements. Administrators also report a lack of incentives as a major obstacle for them to adopt cost-effective selection processes, but are more likely to adopt cost-effective conservation techniques if training and software is provided. These findings provide economists with valuable insights when designing cost-effective mechanisms that could be adopted and used in the future.

e24011 Background: Advanced care planning and living wills are critical components of caring for patients at the end of their lives. Advance directives are designed to be implemented when a patient meets the legal definition of terminal and is deemed incapacitated. By reviewing the electronic health record (EHR) in patients with terminal cancer, we sought to evaluate whether advance directives were appropriately implemented. Methods: A retrospective analysis of the EHR of 500 cancer patients from 1/1/2013 to 12/31/2016 was performed. Data points were manually collected and entered in a central database, and data analysis was completed using SAS. Results: Of the 500 patients, 160 (32%) had an advance directive (AD). The most common clinical terminology used by physicians indicating a terminal diagnosis was “progressive” (36.6%) and “palliative” (31%). The most common clinical terminology indicating incapacity was “altered mental status” (25.6%), and “not oriented” (14%). 34 patients (6.8%) met all criteria of having a terminal diagnosis, a documented AD, and deemed incapacitated. Of these patients who met all of these data points, their ADs were implemented on average 1.7 days (SD: 4.4 days) after which they should have been. This resulted in a total of 58 days of additional care provided to these patients. Conclusions: End-of-life care is a challenging albeit vital part of the practice of medicine. This study provided insight on to how ADs are managed in day to day practice in a hospital. From our analysis, it is clear that physicians are able to identify when a patient is terminal; however, it is typically later than it should have been recognized (and thereby, leading to delays in the implementation of the patient’s AD). Further studies should be performed focusing on harnessing the power of the EHR and providing physicians formative and evaluative feedback of practice patterns to ensure that ADs are honored when appropriate.

Disruptive camouflage involves using coloration to hinder detection or recognition of an object’s outline, or other conspicuous features of its body. This involves using coloration to create ‘false’ edges that make the ‘true’ interior and exterior edges used by visual predators to find and recognize prey less apparent. Disruptive camouflage can therefore be thought of as a manipulation of the signal-to-noise ratio that depends on features of the perceptual processing of receivers. This chapter discusses the multiple mechanisms via which disruptive camouflage is thought to influence visual processing, from edge detection, through perceptual grouping, and then on to object recognition processing. This receiver-centred approach—rather than a prey-phenotype-centred approach—aims to integrate disruption within the sensory ecology of predator–prey interactions. We then discuss the taxonomic, ecological, and behavioural correlates of disruptive camouflage strategies, work on the relationship between disruption and other forms of protective coloration, and review the development of approaches to quantifying disruption in animals.

We begin this chapter by considering the ecological distribution of transparent organisms and, in particular, how they are found predominantly in one particular habitat type (open waters); we aim to explain this trend. A perfectly transparent organism (or part of an organism) will not absorb or scatter incident light. Superficially, transparent might seem like a synonym for visually undetectable, but this is not quite true: we discuss how transparent organisms can still be visually detected by their predators or prey. Conversely, there are circumstances where a little transparency can go a long way to reducing an organism’s visibility. Some body parts cannot be made transparent, but we argue that opaque body parts need not always significantly increase the detectability of a generally transparent organism. We will then consider the distribution of transparency among natural organisms. The distributional observations we seek to explain are: the greater prevalence of transparency among aquatic than terrestrial organisms, and the particular prevalence among midwater species. An alternative but related strategy to transparency, adopted by some midwater fish, and considered later in this chapter, is silvering of the body to provide crypsis by broadband reflection.

Deflection involves prey influencing the position of the initial contact of a predator with the prey’s body, in a way that benefits the prey. These traits might be behavioural, involve morphological structures, or pigmentation and other appearance traits, or combinations thereof. The benefit to the prey is normally considered to be an increased likelihood of escaping the attack, and so the benefit to the prey comes at a cost to the predator. The anti-predatory mechanisms covered in this book vary greatly in current understanding of their taxonomic distribution, and deflection is an extreme example of this. It has been postulated to occur in a sparse and eclectic group of organisms, and the evidence for its existence is quite variable among members of this group. We spend the bulk of this chapter exploring this evidence. We argue that the evidence currently available allows some speculation on the evolutionary ecology of this anti-predatory strategy, and we develop hypotheses that aim to broaden the scope of research into deflective traits.

This chapter concerns Batesian mimicry, which is the resemblance of a palatable species to an unpalatable or otherwise unprofitable species. Often these unprofitable models have warning signals, which the mimic has evolved to copy. The chapter also considers another well-known form of deception, namely masquerade, which is the resemblance of a palatable species to the cues of an object of no inherent interest to a potential predator such as leaves, thorns, sticks, stones, or bird droppings. Batesian mimicry and masquerade share many properties, and both can be considered examples of ‘protective deceptive mimicry’. We begin by briefly reviewing some well-known examples of protective deceptive mimicry. We then compare and contrast the various theories that have been proposed to understand them. Next, we examine the evidence for the phenomenon and its predicted properties, and finally we address several important questions and controversies, many of which remain only partly resolved.

In writing this new edition, we have thoroughly enjoyed exploring the most recent findings in the fascinating world of anti-predatory interactions and the diverse and sometimes astonishing related adaptations. The first section to this book was devoted to studies of crypsis, beginning with a consideration of background matching. Simply matching the background against which you are seen might seem at first pass to be the be all and end all of avoiding detection. The running theme throughout this chapter, however, is that costs and constraints mean that perfect background matching is often not obtained, and this explains why organisms often utilize other mechanisms of reducing their ease of detection....

Elusiveness signals are given by prey during the close approach of a predator, acting to inform the predator that the prey would be difficult to catch and subdue, and, therefore, that an attempt to catch the prey is likely to be unsuccessful. These signals will be restricted to mobile prey that can mount an active response to impending attack and they will not normally be displayed continuously, but instead be triggered by the perception by the prey that they are under imminent risk of attack. There are two different types of such elusiveness signals: 1) pursuit deterrent signals, communicating fleetness or strength to coursing predators, and 2) perception advertisement, communicating detection of a stalking or ambushing predator. Elusiveness signals can only be effective if mounting attacks is expensive to predators in some way. There is also an element of generalization required for elusiveness signals to be effective but, by signalling fleetness, strength, or awareness of the predator, the prey also seek to differentiate themselves from other potential prey. We first document current empirical evidence for elusiveness signalling, before discussing evolutionary considerations—starting with theory on how such signalling might evolve and be maintained—ecological aspects, and co-evolutionary considerations.

Background matching is perhaps the most obvious phenomenon that falls under the label of crypsis. Stevens & Merilaita (2011) describe background matching as situations where ‘the appearance generally matches the colour, lightness and pattern of one (specialized) or several (compromise) background types’. There are fascinating examples of species that behaviourally select their microhabitat and orientation so as to enhance similarity to features of the background, and species that change aspects of their appearance in ways that enhance background matching. The degree of background matching is often imperfect; this is thought to commonly reflect the fact that organisms are viewed against a range of different backgrounds, and so they have evolved appearance traits that offer some degree of matching against several of these. Understanding background matching addresses important issues in evolutionary biology, such as the maintenance of polymorphisms. We discuss how predation rates that depend on the frequency of morphs in the environment may be a common explanation for polymorphic crypsis, and the role search images might play in this process. Achieving highly effective background matching in a complex environment is difficult and this may create room for other types of crypsis.

Startling signals are secondary defences that occur after the focal prey individual has been singled out for attack. Startling signals involve stimulation of the predator’s senses that cause it to delay or break off an attack. The assumption is that even a delay in attack can confer a survival advantage to the prey. This might occur because delay gives the prey an added opportunity to flee, or added opportunity for some other event to occur (perhaps the arrival of a predator of the predator) that causes the predator to break off the attack permanently. Startle signals influence the predator’s behaviour primarily through sensory and/or cognitive manipulation and must be separate from other mechanisms that may also influence predators’ behaviour so as to curtail, delay, or diminish an attack. We first consider the empirical evidence for the existence of such signals, before discussing the evolution of startle signals, the ecological aspects of this defence, co-evolutionary considerations, and suggestions for future research.

Countershading is a coloration pattern where the exterior surfaces most exposed to light, typically dorsal surfaces, are more darkly coloured than those oriented away from light, typically ventral surfaces. Countershading is widely discussed as a camouflage defence, although other functions—such as thermoregulation, abrasion resistance, and protection from ultraviolet light—may also select for countershading. In terms of camouflage, countershading is thought to work by up to six distinct mechanisms. We discuss several key examples of countershading and counterillumination that give insight into some of this complexity, before reviewing the evidence for the effectiveness of each of the six mechanisms. These include relatively simple effects, such as background matching dorsal surfaces against dark oceanic depths when viewed from above and ventral surfaces against downwelling light when viewed from below, but also more complex mechanisms, such as the concealment of cues to three-dimensional shape created by an animal’s self-cast shadows. Following this are sections on the evolution and genetics of countershading, before the chapter concludes with ecological considerations and suggestions for future research.

In 2004, the first edition of ‘Avoiding Attack: The Evolutionary Ecology of Crypsis, Warning Signals, and Mimicry’ by Ruxton et al. was published. The book aimed to provide a systematic and up-to-date review and synthesis of widespread anti-predator defences. In it, we focussed on sensorially mediated defences and the many factors that underpin these adaptations, aiming to set out the state-of-understanding in the fascinating world of anti-predator adaptations, and highlight which topics within the field seem most ripe for further investigation....

Aposematism is the pairing of two kinds of defensive phenotype: an often repellent secondary defence that typically renders prey unprofitable to predators if they attack them and some evolved signal that indicates the presence of that defence. Aposematic signals often work to modify the behaviours of predators both before and during attacks. Warning coloration, for example, may increase wariness and hence improve the chances that a chemically defended prey is released unharmed after an attack. An aposematic signal may therefore first tend to reduce the probability that a predator commences attack (a primary defence) and then (as a component of secondary defence) reduce the probability that the prey is injured or killed during any subsequent attack. In this chapter we will consider both the primary and the secondary effects of aposematic signals on prey protection. We begin first by describing the common features of aposematic signals and attempting to show the wide use to which aposematic signalling is deployed across animals (and perhaps plants too). We then review the interesting evolutionary issues aposematic signals raise, including their initial evolution and their integration with sexual and other signals. We also discuss important ecological, co-evolutionary, and macroevolutionary consequences of aposematism.

In this chapter we consider defences that are usually deployed during, or just before, contact between a prey and its predator: so-called ‘secondary’ defences. Secondary defences are found right across the tree of life and therefore come in very many forms, including: 1.) chemical defences; 2.) mechanical defences; and 3.) behavioural defences. Here we review selected examples that provide useful illustrations of the ecological and evolutionary characteristics associated with secondary defences. We discuss costs of secondary defences, placing emphasis on the consequences of such costs, especially as they relate to forms of social interaction. We show also that the acquisition of secondary defences may modify niche, life history, and habitat range of prey animals and review a well-known and significant study of predator–prey co-evolution of defensive toxins of prey and resistance to those toxins in predators. We include a small selection of examples and ideas from the plant and microbe defence literature where we think a broader perspective is helpful. We begin the chapter by considering the evolutionary mechanisms that favour secondary defence evolution.