Anti-Predator Coloration Symposium

4 & 5 August 2016

Welcome to the symposium and thanks for attending! The symposium will take place on 4 & 5 August 2016, at the Cornwall (Penryn) Campus, which is located approximately 2-3 hours travel from Exeter city (where the main ISBE is held).

Anti-predator coloration is widespread in nature, from and startle displays to warning signals and . on these defences begun with the likes of Wallace and Bates, and actively continues today. Yet there remain many unresolved questions to answer.

The aim of the symposium is to bring together researchers at all career stages interested in defensive coloration in nature. The event will involve a mixture of short (five minute) talks mostly in sets of three, followed by discussions. There will also be four workshops (two simultaneous sessions), exploring key issues and unresolved questions in the subject area.

General Information

Contacts

Organising committee: Martin Stevens, Sara Mynott, Sarah Paul, Emmanuelle Briolat, Jolyon Troscianko, Natasha Price and Ossi Nokelainen.

Enquiries: For general enquiries, please contact Martin ([email protected]) or Sara ([email protected]). For information about the conference dinner, contact Sarah ([email protected]). Send your presentations to Ossi ([email protected]) in advance of the symposium.

Location

The University of Exeter’s Penryn campus is located in South Cornwall, not far from the seaside town of Falmouth. According to higher authority (Sasha Dall, who says he’s done the maths), the campus has the highest number of behavioural-evolutionary ecologists found anywhere in the world. It is also located in one of the most beautiful parts of Britain with many scenic spots, beaches, and wildlife. Behavioural research at the campus focuses on life histories, group behaviour, reproductive , signalling and communication, sensory , human behaviour, and beyond. There are also plenty of groups working on things like sexual conflict, coevolution, disease biology, and conservation.

Getting to Falmouth/Penryn

By train: If travelling from Exeter by rail, take the train from Exeter St David’s to Truro, where you will need to change for the Falmouth branch line service. From here it will be a 15-20 min journey into Penryn, Penmere, Falmouth Town or Falmouth Docks (the latter three stations all in Falmouth). Total journey time is about three hours.

By car: From Exeter, take either the A30 or A38 dual carriageway into Cornwall. Follow the signs to Truro and then Falmouth. Note that normal travel time from Exeter (about 2-2.5 hours) can be much longer if traffic is bad due to road works (plenty of these right now) and tourist traffic.

Accommodation

Check the website (http://www.sensoryecology.com/anti-predator-coloration-symposium/) for some suggestions. We strongly suggest booking early as Falmouth and Cornwall in general are very touristy in the summer.

Things to do

If you have some spare time or are staying for longer, here are a few suggestions.

Falmouth: Often voted/designated as one of the best places to live in the whole of the UK. In and around Falmouth the main attractions include the beaches, specifically Gyllyngvase, Swanpool and Castle Beaches, and Maenporth beach (short walk along the coast path from Swanpool). There are numerous restaurants (lots of seafood places) and cafes, and plenty of pubs (The Front having an outstanding selection of local ales). Other things include the National Maritime Museum, and Pendennis Castle, as well as various watersports like kayaking and surfing. Gyllyngvase and Castle beaches have some of the most biodiverse rock pools in the UK.

Around Falmouth: There are endless things to do, especially to do with history and nature in Cornwall (and numerous tourist books about Cornwall), so here are just a few places close to Falmouth. St Mawes (picturesque village reached by boat) and the Roseland (quaint villages and beaches); Trebah, Glendurgan, and Trellisick Gardens (historical and subtropical gardens – all within 30 min drive); Peninsular (area of outstanding natural beauty and southernmost point of UK mainland); Truro (capital of Cornwall and a nice little city); Helford Passage (area of outstanding beauty, and some good country pubs – can be reached by boat or car); St Michaels Mount (historic monument and beautiful setting – 1 hr drive); St Ives (famous seaside town and art galleries – 1 hr drive); Minack Theatre & Porthcurno beach (historical open air theatre and spectacular beach and setting – 1.5 hr drive), Godrevy and Perranporth beaches (huge sandy beaches north coast, great for surfing – 1 hr drive); Eden project (botanical garden famous for its rainforest biome greenhouse - 1 hr drive); Lanhydrock house (historical house and estate – 1 hr drive), various historical tin mines (Cornwall is famous for its mining heritage)… and much much more.

The Symposium

Detailed directions to the symposium from Falmouth

If coming from Falmouth, take the train from Falmouth Docks, Falmouth Town, or Penmere to Penryn (5-10 mins). Trains leave every half hour and one about 8:20 (based on current timetable) would give plenty of time to arrive for the start of day. Tickets can be bought on the train from the conductor (£2-3 return) if they get to you in time!

At Penryn, leave the station and turn left down the hill, at the cross roads turn left again and walk along the road underneath the railway bridge and follow the road along for about 5 min until it curls round to the right. About here there is a pedestrian entrance on the left to campus. Walk along this part for about 5 min until you get to the second set of steps on your right. Walk up these all the way to the top and it takes you to the heart of the campus.

The symposium is located in the Exchange rooms and . Entrance is opposite the main campus Reception.

Lunch and tea/coffee

We’ll provide tea and coffee etc. during the day.

There are several places to have lunch on campus. The Stannary cafeteria serves a selection of hot meals each day, while Koofi café is a popular spot for pizza. Sandwiches and snacks can also be found at the Stannary and Koofi, as well as in other cafés in the Environment and Sustainability Institute (ESI) building and Performance centre (see campus map).

Talks

We will have a computer with PowerPoint etc. set up for the talks. Due to the way the talks work it would be really helpful if people can send us their talks in advance (we will remind you about this nearer the time).

Each session comprises three (occasionally two or four) sets of talks on a similar topic. We’ve arranged these as best we can, so apologies if your talk seems a bit out of place. Each talk is 5 minutes absolute maximum, and after all three talks the chair will open up the floor for 10 minutes of questions to all speakers. The idea here is to encourage discussions among the speakers and the audience, rather than simply having a series of talks.

We will be strict to keep to time! After four minutes the chair will hold up a photo of an animal with warning signals to warn the speaker they are running out of time. Once the 5 minutes are up, the chair will hold up a photograph of an animal with a startle display, scaring the speaker off the stage through mimicry, conspicuousness, or whatever mechanism works.

Workshops

There are four workshops that will take place, two concurrent sessions, and it’s up to attendees which ones they wish to go to. We have tried to arrange these topics based on the most popular choices and suggestions from the attendees, and also to minimise overlap in peoples’ choices between concurrent sessions. The workshops are as follows:

Workshop 1: Image analysis and vision modelling – new methods and considerations Jolyon Troscianko

Cameras are powerful tools for quantifying colour, pattern and information in a range of disciplines, and can be more flexible, convenient and affordable than alternative tools, such as spectrometers. However, off-the-shelf cameras are designed for producing images for human viewing, and cannot be used for making quantitative measurements without first calibrating the images appropriately. In this workshop I will go over the image calibration process, focussing on our free Image Analysis Toolbox: http://www.sensoryecology.com/image-analysis-tools/ , and providing examples of different photography methods, and potential sources of error. This will include UV photography, and converting images to animal cone-catch values. I will have hands-on examples of different camera setups, and there will be plenty of time for camera-related questions and a discussion of future directions.

Workshop 2: Multi-function / component signals and trade-offs Emily Burdfield-Steel and Jim Barnett Animal colouration fulfils many different functions including communication, , and defence from predators. These various functions have predominantly been studied in isolation, but under natural conditions animal colouration is likely to be affected by multiple selection pressures. Recent research has begun to reveal how these multiple functions interact to either compromise or co-opt signals. For example, certain conspicuous signals can act as camouflage when viewed from greater distances or in certain microhabitats, whereas others are conspicuous only to particular observer visual systems. Many questions still remain and an inclusive framework is needed in order to understand multi-function colouration. In this symposium session we will explore multi- function colouration, what evidence there is for it, and how to best approach these questions in future. The workshop will begin with a brief introduction to multi-function signalling, after which participants will be invited to split into smaller groups and choose from several discussion topics.

Workshop 3: Disruption, dazzle and Joanna Hall and Karin Kjernsmo Despite much recent research into various areas of protective coloration there remain a number of issues that would benefit from further clarification. We will discuss some of these issues during the workshop and by the end would like to have a clear consensus on what we are studying, what the key questions are and, if there's time, what sort of evidence we'd like to collect. Whilst all inter- related, the issues have been separated into three broad topics and we will address these as time allows:

1. : is this one process or several, and how should we define and measure edge disruption (including consideration of coincident disruption)? 2. Varying signals (dynamic dazzle and iridescence): does dynamic dazzle happen in nature, do different types of iridescence have different functions, and could iridescence be considered a form of dynamic dazzle? 3. Motion: can a moving object be concealed and what are the most effective colour patterns for moving groups?

Workshop 4: Warning coloration diversity Ted Stankowich and Brett Seymoure During this workshop we will discuss the diversity of warning signals throughout in the context of proximate and ultimate mechanisms. We will first begin by developing a list of that exemplify diverse warning coloration and those species that exemplify no diversity in warning coloration. Then we will brainstorm different proximate and ultimate explanations for the diversity of signals or lack thereof in the list of aposematic animals. If time permits, we will explore the roll of honest warning signals and warning signal tradeoffs in the context of diverse warning signals. The last 30 minutes of the workshop will be focused on organizing a review paper focused on the discussion during the workshop.

Meal & BBQ The final meal will be held in the heart of Falmouth at the Stable Inn. Offering a selection of pizza’s, pies, and salads, this food and cider house is locally based near the water, and good for summer evenings. We have chosen a restaurant that can cater for a wide variety of dietary requirements, and is also reasonably priced. If you stated on the sign-up that you would like to join us, we will be in touch soon with full details. The restaurant requires a deposit paid in advance, and so to keep things simple for everyone we will ask those who want to attend to give us the money in advance (by 25th July). Price is £16.60 per head (including 10% service fee) and includes garlic bread starter, main, and side salad. There is a bar for buying drinks.

Detailed Timetable Day 1 (4th August)

9.15-9.25: Welcome and Information

9.30-9.50: Talk session 1: 1 – Warning signal diversity Chair: Anne Winters

Katja Rönkä Role of in geographic vs. local variation in the warning coloration of an aposematic

Emily Burdfield-Steel Truth and Lies: not quite honest signalling in an aposematic moth

Julien Renoult Methods of quantifying visual dissimilarity between colour patterns

9.55-10.20: Talk session 2: Aposematism 2 – Warning signal Chair: Anne Winters

Olof Leimar How should we understand the evolution of warning coloration?

James Barnett Distance-dependent defensive colouration in the dyeing poison frog (Dendrobates tinctorius Dendrobatidae)

Theodore Stankowich Predator learning about aposematism in striped

10.25-10.55: Coffee break

10.55-11.20: Talk session 3: Camouflage 1 – Behaviour and vision Chair: Will Allen

Pinja Que Adaptive mechanism of camouflage in Kentish plover during population divergence

Kate Marshall Microhabitat choice in island enhances camouflage against avian predators

Sandra Winters Primate camouflage in the of felids, raptors, and conspecifics

11.25-11.55: Talk session 4: Camouflage 2 – Disruptive colouration Chair: Will Allen

Jolyon Troscianko Quantifying camouflage: how to predict detectability from appearance

Brett Seymour Keeping the band together

Alice Exnerová Effect of body-margin shape on detectability of bark bugs (Heteroptera: Aradidae) for avian predators

12.00-12.25: Talk session 5: Camouflage 3 – Exploring different types of camouflage Chair: Will Allen

Yang Niu Cryptic coloration in alpine plants from SW China

Martin Stevens Using online Easter egg hunts to study camouflage

John Skelhorn Aggressive masquerade: a deadly case of mistaken identity?

12.30-1.30: Lunch

1.30-3.00: Workshops

Workshop 1 – Image analysis and vision modelling – new methods and considerations Jolyon Troscianko

OR

Workshop 2 – Multi-function / component signals and trade-offs Emily Burdfield-Steel & Jim Barnett

3.00-3.30: Coffee break

3.30-3.55: Talk session 6: Aposematism 3 Chair: Carita Lindstedt-Kareksela

Hannah Rowland The fitness consequences for aposematic prey of attack by predators that vary in their dietary wariness and discrimination learning behaviour

Emmanuelle Briolat Testing the effects of burnet moth colour and pattern on predation

Richard Simpson Conspicuousness of the venomous Gila Monster as a function of age

4.00-4.25: Talk session 7: Aposematism 4 Chair: Carita Lindstedt-Kareksela

Denise Dalbosco Dell’Aglio Avoidance of an aposematically coloured by wild in a tropical forest

Sam Green Fluorescent froth frightens feathered foes

Thomas Schultz The role of iridescent in predator avoidance strategies

4.30-4.40: Wrap-up, information for evening plans

Evening: BBQ (weather-dependent), pub trip, free time

Day 2 (5th August)

9.00-9.05: Welcome and information

9.05-9.35: Talk session 8: Camouflage and colour change 1 Chair: Kate Marshall

Ossi Nokelainen Can juvenile shore crabs developmentally optimise their camouflage?

Rafael Duarte Camouflage efficiency in Hippolyte prawns: how to survive in a multi-coloured ?

Jennifer Easley Colour change in the shore crab

Sara Mynott Camouflage under climate change: will warmer oceans matter?

9.40-10.05: Talk session 9: Camouflage and colour change 2 Chair: Kate Marshall

Roger Hanlon Rapid adaptive camouflage in

Sam Smithers Colour change and camouflage in rockpool fish

Jenna Proctor Camouflage of the Furrowed crab (Xantho hydrophilus)

10.10-10.35: Talk session 10: Multifunctionality of colour and pattern changes Chair: Kate Marshall

Will Allen Evolution of pattern in geckos

Sebastian De Bona Post-attack deimatic display: bad timing or optimal compromise?

Robert Heathcote Anti-predatory function of iris colour in guppies

10.40-11.10: Coffee break

11.10-11.35: Talk session 11: Aposematism 5 – Signal honesty Chair: Emmanuelle Briolat Sarah Paul Eggscellent defence strategies – the role of maternal effects in ladybird laying strategies

Kyle Summers Evidence for (lack of) honest signalling in a poison frog

Carita Lindstedt-Kareksela Effect of parental care on the development of honest warning signals in in the burying (Nicrophorus vespilloides)

11.40-12.05: Talk session 12: Chair: Sarah Paul

Innes Cuthill Eyespots: mimicry or just conspicuous?

Karin Kjernsmo Resemblance to the enemy’s eyes underlies the adaptive function of intimidating eyespots

Casey Peet-Paré mimicry in the

12.10-12.35: Talk session 13: Evolution and theory Chair: Sarah Paul

Anne Winters Marine : a putative mimicry ring in nudibranch molluscs

Joseph Jordania The singing and painted ape: an aposematic theory of human evolution

Gabriella Gamberale-Stille Melanism and the feature saltation hypothesis of mimicry evolution

12.40-13.40: Lunch

1.40-3.00: Workshops

Workshop 3 – Disruption, dazzle and iridescence Joanna Hall & Karin Kjernsmo

OR

Workshop 4 – Warning coloration and diversity Ted Stankowich & Brett Seymoure

3.00-3.30: Coffee break

3.30-3.55: Talk session 14: Multifunctional signals and camouflage Chair: Sam Smithers

Tom Cronin The other color: dealing with predators in polarized

Amanda Franklin Camouflage and signalling in stomatopods

Wladimir Alonso The “Hyper-Visible World" hypothesis – An explanation for the dazzling colours of coral reef fish

4.00-4.25: Talk session 15: Movement and 1 Chair: Sam Smithers

Nick Scott-Samuel Colouration, oddity and confusion

Joanna Hall Dazzle under stress

Diana Umeton Avoiding attack: the need for speed

4.30-4.55: Talk session 16: Movement and dazzle camouflage 2 Chair: Sam Smithers

Benedict Hogan Dazzle camouflage, target tracking and the confusion effect

Candy Rowe Movement and defensive coloration

Pavel Stys Occurrence and function of iridescence in Heteroptera

4.55-5.00: Wrap-up, information for evening plans

7.00: Symposium dinner

Abstracts & Attendees

In alphabetical order:

Evolution of color pattern in geckos Will Allen Swansea University In vertebrates, color pattern diversity at macroecological scales has been intensively studied in some groups (fish, , birds), but studies of reptiles are limited to a few examples. Geckos show a wide range of variation in dorsal color patterns but their function(s) is still largely unknown. We test competing hypotheses by studying the influence of phylogeny, time of activity (diurnal vs nocturnal), and habitat use (sand, arid rocky outcrops, forested rocky outcrops, shrub, tree, and leaf litter) on dorsal color pattern variation in geckos. We create an image database of 439 gecko species and use a card sorting task to arrange images along gradients of pattern similarity. Phylogenetic comparative methods tested predictions, for example for correlated evolution between disorganized patterns and complex , suggesting a cryptic function. Our results showed a strong influence of phylogeny on color pattern variation but little effect of activity time or habitat type.

Evolution of bright colours in animals: worlds of prohibition and oblivion Wladimir Alonso University of São Paulo Because the ability to hide in plain sight provides a major selective advantage to both prey and predator species, the of the striking colouration of some animal species (such as many coral reef fish) represents an evolutionary conundrum that remains unsolved to date. Here I propose a framework by which conspicuous colours can emerge when the selective pressures for camouflage are relaxed (1) because camouflage is not essential under specific prey/predator conditions or (2) due to the impossibility of reducing the signal-to-background noise in the environment. The first case is found among non-predator-species that possess effective defences against predators (hence a “Carefree World”), such as the strong macaws’ beaks and the flight abilities of . The second case is found in diurnal mobile fish of coral reef communities, which swim in clear waters against highly contrasting and unpredictable (hence an "Hyper-Visible World”). In those contexts the selective pressures that usually come secondary to camouflage (such as sexual, warning, species recognition or territorial display) are free to drive the evolution of brilliant and diverse colouration. This theoretical framework can also be useful for studying the conditions that allow for conspicuousness in other sensory contexts (acoustic, chemical, electrical, etc.).

Distance-dependent defensive colouration in the dyeing poison frog (Dendrobates tinctorius Dendrobatidae) James Barnett University of Bristol The Neotropical poison frogs (Dendrobatidae) are widely known for their highly conspicuous aposematic signals. These frogs are not, however, immune to predation, and recent work is beginning to highlight how different evolutionary pressures interact to favour both conspicuousness and camouflage within a single colour pattern. It has been suggested that to balance the costs and benefits of each defensive strategy, certain species take advantage of limitations in predator visual acuity to produce patterns which are perceived differently depending on the distance of the observer. Using field and laboratory psychophysics, and visual modelling from calibrated images, we find that the seemingly conspicuous yellow-and- colours of the dyeing poison frog (Dendrobates tinctorius) are highly detectable at close range, but match the background when viewed from greater distances. This suggests that D. tinctorius combines background-specific camouflage with aposematism, to produce a highly aversive signal while also minimising the risk of being detected.

Testing the effects of burnet moth colour and pattern on predation Emmanuelle Briolat Centre for Ecology and Conservation, University of Exeter Aposematism, or warning colouration, is a well-established anti-predator strategy, whereby toxic or otherwise defended prey advertise their unprofitability to predators with conspicuous colours and patterns. Though the cost of increased apparency enforces some level of reliability in aposematism, the idea of a quantitatively honest relationship between signal and defence remains more controversial, with conflicting model predictions and empirical results in different species. My project addresses this issue by investigating the wing colours and chemical defences of day-flying burnet (Zygaenidae), which both sequester and synthesise cyanogenic glycosides. To provide a comprehensive picture of aposematism in these species, I am combining several approaches, principally digital image analysis and toxicity tests, but also dietary experiments testing the effects of limitation and artificial predation trials in the field. Together, these experiments explore natural variation in burnet moth colouration, how this relates to levels and ultimately affects predator behaviour. The predation experiments demonstrated no evidence of a protective effect of iridescence, and, contrary to expectations, suggested that being redder and having larger spots increased predation of burnet-mimicking prey, a result which could be strongly linked to seasonality and predator experience of burnet moths.

Truth and Lies: not quite honest signalling in an aposematic moth Emily Burdfield-Steel University of Jyväskylä Aposematism is the combination of a primary signal with a secondary defence that predators must learn to associate with one another. However, the level of defence may not be uniform across all members of a species. We investigated the honesty of warning signals in the wood moth (Parasemia plantaginis). This species produces defensive fluids when attacked, and advertises this protection with bright colours on its hindwings. Female colouration varies continuously from yellow to , with red providing the stronger anti-predator signal. We presented defensive fluids from female moths to wild -tits, in the absence of any visual cues, to determine their effectiveness against avian predators. We show that food deprivation during early life can influence the efficacy of chemical defence, and female colour is an honest signal for some aspects of unpalatability. However, the secondary chemical defensive may be multimodal, with differences in taste and smell affecting their efficacy.

The other color: dealing with predators in polarized light Tom Cronin University of Maryland Baltimore County It is obvious that animals signal to each other, and to members of other species, using colored signals and patterns. They also use this realm of body decoration to conceal themselves in appropriate environments. It is less well recognized that animals must also face conspecifics and opponents that use polarization vision to view their signals and break their camouflage. In this talk, I will discuss how polarization patterns (often in combination with color) are used for display and for camouflage by marine animals, including shrimps, cephalopods, and marine fishes. Both display and camouflage will be addressed, particularly since the role of polarized light in concealment has been generally mischaracterized in the literature.

Eyespots: eye mimicry or just conspicuous? Innes Cuthill University of Bristol Many species, across diverse taxa, bear conspicuous markings with concentric rings of varying degrees of circularity. These ‘eye-spots’ sometimes have a role in mate attraction but more typically are thought to have an anti-predatory function, acting to startle or intimidate would-be predators, or to deflect attacks from more vulnerable parts of the body. There is experimental support for all these functions, but the most persistent, appealing and yet controversial hypothesis is that the effectiveness of the most striking of these patterns results from their mimicry of raptor eyes. There are some data supporting this view, but rather more that suggests the eye-mimicry is incidental and it is conspicuousness that reduces predation. We tested the effectiveness, against avian predation, of different wing-spot patterns from real Lepidopteran species when presented on artificial prey in the field. Survival was strongly related to raptor-eye-likeness, as objectively measured using an ‘eye-detector’ developed using machine learning.

Post-attack deimatic display: bad timing or optimal compromise? Sebastiano De Bona University of Jyväskylä Many prey species rely on deimatic (or startle) displays to halt predators’ attacks. This behaviour is thought to interrupt the predation sequence after an encounter, but before subjugation by the predator. The mountain katydid (Acripeza reticulata) conceals a conspicuous red and blue abdomen under a cryptic wing pattern. A bitter abdominal exudate makes the abdominal pattern potentially aposematic. The abdomen is displayed only after a tactile stimulus during a subjugation attempt. This appears to be a suboptimal strategy, preventing the benefits from the constant display of the warning signal, while the timing of the deimatic display fails to halt an attack. In order to understand this post-attack deimatic display we staged encounters between katydids and both natural and model predators (magpies and chicken). The display improved survival against chicken, whereas magpies ignored it, consuming all katydids they detected. We propose that inverse predator responses can explain katydids’ articulate defence.

Avoidance of an aposematically coloured butterfly by wild birds in a tropical forest Denise Dalbosco Dell'Aglio University of Cambridge Birds are considered to be the primary selective agents for warning coloration in butterflies. Bright coloration plays an important role in promoting the avoidance of distasteful prey by birds. We tested the hypothesis that warning coloration promotes predator avoidance by means of a field experiment using distasteful model butterflies. Artificial butterflies with a Heliconius colour pattern unknown to local birds were generated using vision models, coloured or achromatic, and hung in branches in a tropical forest. Two sequential trials were conducted at each site in order to test avoidance by naïve and experienced predators. Coloured butterflies were attacked significantly less in the second trial, but there was no significant decrease in predation on achromatic models. Our results imply an important role for colour in enhancing aversion of aposematic butterflies and also demonstrate that previous experience of distasteful prey can lead to enhanced avoidance in subsequent trials, supporting mimicry theory.

Camouflage efficiency in Hippolyte prawns: how to survive in a multi-coloured habitat? Rafael Duarte University of São Paulo Colour camouflage is a common mean to avoid predation in nature and can be achieved by mechanisms such background matching. The European prawn Hippolyte varians and its South Atlantic congener H. obliquimanus are characterized by distinct colour morphs, usually found associated with banks of macroalgae in rocky coastal areas. We collected data on the appearance of morphs to the macroalgae they live to evaluate whether prawn colour mimicry is efficient to decrease the probability of detection by a visual predator. We modelled the vision of three fish predators, characterized by distinct visual systems, and calculated colour differences between prawns and backgrounds. Both species present efficient mechanisms to reduce detection by predators, showing lower colour and luminance differences when viewed in the macroalgae they were sampled. Similar adaptive functions of colour camouflage in Hippolyte prawns are key features to understand mechanisms for maintenance of colour variability in this important group.

Colour change in the shore crab Jennifer Easley Cambridge University/Exeter University Probably the most common strategy involved in camouflage is for an animal to simply match the colour of its background. However, very little is known regarding the mechanisms underlying this process and their relative importance. This project uses common shore crabs (Carcinus maenas) to determine the role of colour change and developmental plasticity in tuning individual matches to the background. Here, I present the results of experiments with juvenile shore crabs, investigating their ability to change colour and brightness. Crabs were placed in tanks on substrates that differed either in brightness (black or ) or colour (red or green-blue) and kept for 5 weeks. Each individual was photographed at regular intervals to assess changes in carapace coloration. Results showed crabs are able to substantially modify their appearance in line with their backgrounds, especially as they go through moults. This shows that -environment matches can be strongly influenced by phenotypic plasticity.

Effect of body-margin shape on detectability of bark bugs (Heteroptera: Aradidae) for avian predators Alice Exnerová Department of Zoology, Charles University in Prague Studies of camouflage are usually focused on the coloration and pattern arrangements. However, some prey species have irregular body margins, which may add to effectiveness of their camouflage. We tested an effect of body-margin shape on the detectability of bark bugs for juvenile and adult great tits (Parus major). We used photographs of two species of Neotropical genus Dysodius matching in size and coloration, but differing by the shape of body margin (straight or serrate). Photographs of both species were taken on several backgrounds of tree barks and the birds were trained to search for the bugs baited with a mealworm hidden beneath. Juvenile birds were generally faster than adults in searching for the bugs, and detection times were influenced by background type. Bugs with serrated body margin were more difficult to detect, but the effect was evident only in juvenile birds searching for prey on difficult backgrounds.

Camouflage and signalling in stomatopods Amanda Franklin Tufts University Animal colouration can be a trade-off between providing camouflage and maximising signal conspicuousness. One way to maintain both colour signal quality and camouflage is to have a signal that can be physically hidden whilst the predominant body colouration provides camouflage. Here, I investigate if this is the case in a stomatopod, Neogonodactylus oerstedii. Neogonodactylus oerstedii are preyed upon by fish, cephalopods and elasmobranchs. They vary in body colour, from sandy to green. This variation may provide camouflage in the different habitats (seagrass and rubble) in which they are found. They also have a coloured patch that is used as a signal in agonistic encounters. The brightness of this patch varies with the habitat they are located. Here, I investigate if the different colour morphs provide effective camouflage from a fish predator in seagrass and rubble habitats and if the variation in signal brightness maximises signal conspicuousness in these habitats.

Melanism and the feature saltation hypothesis of mimicry evolution. Gabriella Gamberale-Stille Department of Zoology, Stockholm University, Sweden Mimicry has been suggested to evolve through a two-step process, with an initial saltational change in appearance followed by fine-tuning towards greater model similarity. In a series of theoretical and experimental studies we have developed and evaluated predator feature learning and categorization as an explanation for the initial change that allows a species to gain entry to mimicry. With inspiration from animal learning theory, we have argued that predators perceive prey as having several traits, but the traits differ in their importance for learning so that high-salience traits overshadow other traits and are used in a feature-like manner to discriminate prey. I will discuss the role of changes in melanism as an important class of feature mutations with great impact on predator categorization and mimicry evolution. I address several natural cases of mimicry evolution, such as in the Papilio machaon group, and discuss reconstructions of mimicry evolution.

Fluorescent Froth Frightens Feathered Foes Sam Green University of Exeter Fluorescence has been described in a variety of species, with numerous suggested ecological functions. However to our knowledge its use has never been demonstrated as an anti-predator defence. Predators impose strong selection pressures on their prey, and consequently there are a huge variety of anti-predation strategies. Many of these defences occur in sensory modalities unperceivable to humans. A recent discovery has revealed that the slime exuded by the garden snail (Cornu aspersum) when threatened, fluoresces yellow under ultraviolet illumination. It was suggested that this might function as a deterrent against avian predators. Experiments were run in artificial and natural systems, containing avian predators, to investigate the effect of this fluorescence. We demonstrate that the fluorescence of C.aspersum has a significant effect upon the feeding behaviour of avian predators. This research presents the first empirical evidence for the use of fluorescence as a predator deterrent in the natural world.

Dazzle under stress Joanna Hall University of Bristol Static high contrast (‘dazzle’) patterns, such as zigzags, have been shown to reduce the perceived speed of an object. Dynamic stripe patterns moving in the same direction as the target increase the perceived speed of that target, whilst dynamic stripes moving in the opposite direction to the target reduce the perceived speed. Using the CO2 challenge, we show that this effect is robust to stressful conditions.

Rapid Adaptive Camouflage in Cephalopods Roger Hanlon Marine Biological Laboratory , and have evolved an unusually fast and diverse set of body patterns used for both primary and secondary defense. They live in a wide range of complex environments and are preyed upon by a wide range of visual predators. I will present recent field work and lab experiments on multiple tactics that they use to avoid visual predation.

Anti-predatory function of iris colour in guppies Robert Heathcote University of Exeter Functional studies on eye colouration have mostly focused on how prey species camouflage their eyes, and yet many animals have conspicuous eye colouration, which is largely unexplored. I will present some preliminary findings and hypotheses on the function of eye colour change in Trinidadian guppies, which express conspicuous black irises when they inspect large predatory fish.

Dazzle camouflage, target tracking and the confusion effect. Benedict Hogan University Of Bristol The influence of coloration on the ecology and evolution of moving animals in groups is poorly understood. Animals in groups benefit from the ‘confusion effect’, where predator attack success is reduced with increasing group size or density. This is thought to be due to a sensory bottleneck; an increase in the difficulty of tracking one object among many. Motion dazzle camouflage has been hypothesised to disrupt accurate perception of the trajectory or speed of an object or animal. We investigated the suggestion that dazzle camouflage may therefore enhance the confusion effect. Utilising a computerised experiment with human predators, we found that targets in groups with stripes that are parallel to the targets’ direction of motion are harder to track than ones with orthogonally striped patterns. Parallel striped targets also interact with the confusion effect to a greater degree than those with orthogonal stripes and more conventional background matching patterns.

The singing and painted ape: an aposematic theory of human evolution Joseph Jordania University of Melbourne Our remarkably complex rhythmic, melodic and harmonic abilities cannot be explained by any current evolutionary theory. Here I suggest that musicality was actually a fundamental element that allowed the transition from discrete and afraid tree-living monkeys to assertive, erect and noisy hunt-stealers from . Loud rhythmic music, sung, drummed and stomped by a group of humans, is able to scare away the most formidable predators, and can put singers into the state of the “battle trance” where participating individuals do not feel fear and pain and are religiously dedicated to the group interests. Once coordinated conspicuousness was subjected to positive selection, other contributing features from other sensorial realms were also of adaptive value for this purpose, such as powerful set of visual signals like bipedal posture, tallness, aggressive body ornaments and the use of colouring (particularly red) substances, which is widespread in warriors of many tribes even today.

Resemblance to the enemy’s eyes underlies the adaptive function of intimidating eyespots Karin Kjernsmo University of Bristol Colour patterns of prey provide a large variety of striking examples of anti-predator , but because they involve predator psychology, their functions are not always well understood. For example, some eyespots intimidate predators, but the reason for this response, and thus for the common occurrence of this pattern has remained a conundrum. Two alternative hypotheses propose that (1) the eyelike appearance of the mark falsely indicates the presence of the predator’s own enemy or that (2) predators are hardwired to be cautious towards conspicuous signals. Previous research has pertained to eyespots of butterflies, but by utilizing the lateral position of eyes in fishes, we could produce eyelike displays that do not have the appearance of eyespots and reveal eye-mimicry as the key factor evoking hesitation in predators. Moreover, we show that this is because predators associate eyelike displays with the threat caused by the presence of their own enemies.

How should we understand the evolution of warning coloration? Olof Leimar Stockholm University The traditional view on warning coloration dates back to discussions between Wallace, Bates and Darwin in the 1860s and proposes that aposematism works because predators learn through experience to associate the coloration with unpalatability. Both Zahavi and Grafen have interpreted warning coloration as handicap signaling. Grafen developed the idea that palatable prey would often suffer costs if they were conspicuous, because predators find them more readily and learn that they are good to eat, so the honesty of the signal is tested. I will address the question of how in fact has moulded warning signals, comparing ideas base on the handicap signaling with the possibility that warning signals have primarily been shaped by their role in the learning process, for instance to promote rapid learning and high memorability. I will argue that the latter perspective is likely to be the most important.

Effect of parental care on the development of honest warning signals in in the burying beetle (Nicrophorus vespilloides) Carita Lindstedt-Kareksela University of Jyväskylä Burying (Nicrophorus vespilloides) bear distinctive, genetically and phenotypically varying aposematic -black patterning on their elytra and produce fluid from their abdomen when threatened. We have found that individuals that receive high amount of parental care as a larva, have larger orange patterning and produce more efficient and higher amount of defence fluid in comparison to individuals who receive lower amount of parental care. In addition, the orange elytral patterning accurately advertises the extent to which an individual is chemically defended, because individuals with larger orange markings on their elytra produce more anal exudates when threatened. However, this correlation exists only on individuals that receive high amount of parental care. Therefore, the early developmental environment may have long-term effects on antipredator defences and development of honest warning signals.

Microhabitat choice in island lizards enhances camouflage against avian predators Kate Marshall University of Cambridge Camouflage can be enhanced by genetic adaptation to different environments. It is less clear how individual behaviour improves camouflage effectiveness. We investigated whether individual Aegean wall lizards (Podarcis erhardii) inhabiting different islands rest on backgrounds that improve camouflage against avian predators. In free-ranging lizards, we found that dorsal regions were better matched against chosen backgrounds than against other backgrounds on the same island, indicating background choices heighten individual-specific concealment. This effect was more evident in females and less distinct on islands with fewer avian predator species. However, in an arena experiment, lizards did not choose the background that improved camouflage, probably due to the artificial conditions. Our results suggest that substrate preferences can enhance individual lizard camouflage in natural microhabitats, and that such may be sexually dimorphic and dependent on predation risk. This research emphasizes the links between ecology, behaviour, and appearance in intraspecific colour variation and local adaptation.

Camouflage under climate change: will warmer oceans matter? Sara Mynott University of Exeter Camouflage is the most common anti-predator defence in nature and many species can fine-tune their coloration to better conceal themselves from predators. Given the importance of camouflage in evading predator detection, it is important to understand how environmental change will affect this process. We investigated how climate-related stressors, particularly ocean warming, influence camouflage in the shore crab, Carcinus maenas. Within 5-25 °C tanks, individuals were allocated to different backgrounds and photographed to monitor long-term changes in coloration. These photos were mapped to models of fish vision, allowing camouflage to be quantified from the predator’s perspective. Here we show that juvenile shore crabs have a plastic response to their surroundings and match their background better after moulting. Laboratory results reveal that this process occurs faster with increasing temperature, indicating ocean warming could reduce predation risk. These findings have implications for how predator-prey dynamics will respond to climate change in the marine environment.

Cryptic coloration in alpine plants from SW China Yang Niu Kunming Institute of Botany, Chinese Academy of Sciences Camouflage is not the exclusive strategy of animals, plants may also use the similar method to avoid attack. In the alpine area of Qinghai-Tibet Plateau, several plant species from different taxa exhibit typical cryptic colouration. Using Corydalis species (with dimorphic leaf colour within populations) as the material, we investigated the influence of the rock-like leaf colour on plant fitness under the context of cost-benefit trade off. Now we are working on the divergence of cryptic colour among populations with various background substrate.

Can juvenile shore crabs developmentally optimise their camouflage? Ossi Nokelainen Centre for Ecology and Conservation, University of Exeter Green shore crabs (Carcinus maenas) are highly variable in coloration and hence can blend effectively into visually heterogeneous background habitats. They are known to undergo developmental changes in coloration, but whether this is related to camouflage optimisation is not well known. We used multispectral imaging to quantify background matching in juvenile shore crabs in a long-term, factorial common garden experiment. We found that 66 crabs changed significantly in colour and pattern over 10 weeks. However, the background match improved only on mudflat backgrounds, whereas they became mismatched with respect to the rockpool backgrounds. Our findings provide insight about ontogenetic changes in crab coloration and call for further investigation on the survival value of this colour change in the wild.

Eggscellent defence strategies – the role of maternal effects in ladybird laying strategies Sarah Paul University of Exeter Early life stages are commonly the most vulnerable to predation, particularly in those species with no parental care. Predators can be deterred via offspring defence mechanisms e.g. aposematism. However predation risk, and therefore the adaptive benefit of such costly defences and any consequent trade-offs, varies between environments. Maternal effects are a powerful mechanism by which offspring defence level can be matched to the degree of offspring predation risk. Whether females of aposematic species modulate offspring toxin levels and/or signalling honesty depending on the offspring predation risk is however, unknown. We investigated reproductive investment, including egg toxin level and signalling honesty, of two-spot ladybirds (Adalia bipunctata) under experimentally manipulated levels of perceived egg predation risk from invasive heterospecific, native heterospecific, and conspecific larval ladybirds. Results are discussed in the context of theory on fixed and plastic maternal investment strategies and maternal effects.

Hoverfly mimicry in the ultraviolet Casey Peet-Paré Carleton University (Diptera:Syrphidae) are well-known Batesian mimics of hymenopterans. So far research on hoverfly mimicry has focused on the visible colours (400-700nm) of mimics and their models. However, potential hoverfly predators, such as birds, insects, and arachnids, can also see ultraviolet (UV) light (300-400nm) and therefore UV colours. Using published mimic and model pairings of European species we assessed mimicry from a predator perspective using UV photography (and spectrophotometry). A number of hoverfly mimic species and hymenopteran model species have colour patterns that reflect the UV. We describe the nature of these UV patterns in each species, with particular reference to whether mimics match their models in the UV spectrum.

Camouflage of the Furrowed crab (Xantho hydrophilus) Jenna Proctor University of Exeter The most common form of anti-predator defence is perhaps camouflage. However there are many types of strategies employed by animals within camouflage, of these background matching is likely to be most common. Individuals who background match as a form of camouflage tend to either match their colour to backgrounds through behaviour or change colour to match their current background. Colour change is known among the animal kingdom and our ability to quantify this colour change is becoming more sophisticated. Here we test whether the juvenile furrowed crab (Xantho hydrophilus) are capable of colour change for camouflage by placing them on either (experiment1) or red and green (experiment 2). Using image calibration and models for avian vision we look to see if individuals show a large perceptual change in appearance.

Adaptive mechanism of camouflage in Kentish plover during population divergence Pinjia Que Beijing Normal University Ecological speciation arises because of divergent selection. The most obvious source of divergent selection stems from differences between environments. Population differences in visual environment can lead to divergence in multiple components of including signalling traits and colour patterns important for . Because camouflage can determine prey/predator fitness by avoiding detected by predator/prey. The Kentish plover (Charadrius alexandrinus), a small shorebird which has a broad geographic distribution in Eurasia, breeds on coastal wetland or saline lakes inland in China. The populations breeding in south China were consider as a subspecies C. a. dealbatus, which were paler and more rufous than C. a. alexandrines breeding in north China. The difference of between two subspecies could be the result of different background colour. The breeding habitat in south China is rufous sand beach, in north China is darker soil flat.

Methods of quantifying visual dissimilarity between colour patterns Julien Renoult CNRS, France Strategies of anti-predator coloration often rely on the extent of visual dissimilarity between stimuli. For example, mimetic and cryptic animals resemble other animals or their backgrounds, respectively, while aposematic advertisements should be unique to facilitate recognition and memorization. A challenge for ecologists is to quantitatively characterize the dissimilarity among colour patterns. In this presentation, we will present different methods for quantifying this dissimilarity that are adapted from the fields of visual computing and artificial intelligence. We will discuss their relevance for modelling perception by non-human organisms and will present an on- going project that aims to compare the methods with each other and with empirical data.

Role of predation in geographic vs. local variation in the warning coloration of an aposematic moth Katja Rönkä University of Jyvaskyla The wood tiger moth (Parasemia plantaginis) is an aposematic species with white, yellow or red hind wing coloration. We asked whether differences in selection by predators could explain geographic differences in warning signals. In a large-scale field experiment in four geographic locations in Estonia, Scotland, Georgia and Finland we exposed artificial moths of white, yellow and red wing coloration to natural predators. We also tested whether predators generalize other color morphs if reinforced first with another. Predation pressure differed between the populations and natural selection favored locally common morphs in Scotland (yellow) and in Georgia (red) as expected according to the theory of aposematism. In Finland (polymorphic population) and in Estonia, where the predation pressure was very low, we did not find evidence of positive frequency dependent selection. We suggest that polymorphism in Finnish populations can be explained by the locally variable predation, migration and predators’ generalization among morphs.

Movement and defensive coloration Candy Rowe Newcastle University Most studies investigating the efficacy of defensive coloration strategies, such as warning signals and camouflage, have used prey that are stationary. However, prey often have to move, perhaps to find food or mates, which can affect how well their defensive strategies work against visually hunting predators. Movement affects how visual patterns are perceived, but also what predators learn about prey. I will discuss some of the putative interactions between movement and prey patterning, and present data from praying mantids showing how movement can affect predatory behaviour towards differently patterned targets.

The fitness consequences for aposematic prey of attack by predators that vary in their dietary wariness and discrimination learning behaviour Hannah Rowland University of Cambridge Prey animals often advertise their chemical defences to predators by a distinctive and conspicuous visual appearance known as aposematic colouration. Predators vary in their reactions to aposematic prey, which can be due to neophobia and dietary wariness, or differences in their learning abilities, or motivation to learn to avoid aposematic prey. Both wariness and learning have been independently connected with variation in the effectiveness of aposematic signals. However, whether a predator’s wariness towards aposematic prey interacts with its ability to learn about aposematic prey, and what combined effect these behaviours have on aposematic signals has not been tested empirically. I'll discuss how differences between predators in their learning behaviour can exert strong selection on aposematic signals.

The Role of Iridescent Colors in Predator Avoidance Strategies Thomas Schultz Denison University While there has been a surge of interest in iridescent colors as sexual signals, far less attention has been paid to the potential role of iridescence with its unique properties in anti-predator defenses. The production of interference colors by thin cuticular layers is widespread among insects and it has been shown that additive mixing of iridescent colors in tiger beetles provide an especially malleable mechanism for cryptic coloration. There are a few anecdotal examples of distasteful insects that pair saturated iridescent with bright complementary that may provide an aposematic signal. However, iridescent colors by themselves are inconsistently conspicuous and often concealed in many insects. It is proposed that iridescent and specular colors that are intermittently visible disrupt a predator's visual contact with prey during an attack. Although some attempts have been made with human subjects, it remains difficult to conceive of methods to test this hypothesis experimentally.

Colouration, oddity and confusion Nick Scott-Samuel University of Bristol The "confusion effect" is conventionally defined as a “reduced attack-to-kill ratio experienced by a predator resulting from an inability to single out and attack individual prey in a group” (Krause & Ruxton, 2002). I will present data on the interaction between the confusion effect, as measured by a recently-developed tracking task (Scott-Samuel et al., 2015), and manipulations of colouration and oddity.

Keeping the band together Brett Seymoure Arizona State University and Smithsonian Tropical Research Institute Many animals have stripes and bands that may function disruptively, in which patterns break up the animal’s outline through false edges or boundaries, increasing survival in animals by reducing predator detection and/or preventing recognition. We tested the possible disruptive function of wing band patterning in a butterfly, Anartia fatima, using artificial paper and plasticine models in Panama. One model type had the band shifted to the wing margin (non-disruptive treatment) and another model had a discontinuous band located on the wing margin (discontinuous edge treatment) and kept the natural wing pattern to represent the false boundary treatment. False boundary models had higher survival than the other models. Our results demonstrate the importance of wing bands in reducing predation on butterflies and show that markings set in from the wing margin can reduce predation more effectively than marginal bands and discontinuous marginal patterns.

Conspicuousness of the venomous Gila Monster as a function of age Richard Simpson Arizona State University Animal coloration serves many functions ranging from mate choice to warning signals. Furthermore, coloration is spatially and/or temporally dynamic, and animals can change color in several ways, including as they age. Predation pressures on animal coloration can vary upon prey age, and thus prey color change with age can affect prey survival. Here we tested how age dependent color change in the venomous Gila Monster, Heloderma suspectum, affects conspicuousness to avian predators. We predicted that neonates would be more conspicuous to warn predators, while adults would be less conspicuous to reduce predator detection due to greater mobility during adulthood. Using wild caught Gila Monsters throughout Arizona, USA, we measured coloration and background with spectroradiometry and then calculated conspicuousness using avian visual models. We found that neonate Gila Monsters were chromatically more conspicuousness than adults. We then discuss these findings in context of aposematic theory and predator-prey interactions.

Aggressive masquerade: a deadly case of mistaken identity? John Skelhorn Newcastle University Masquerading animals resemble inanimate, inedible or innocuous objects found in their local environment such as twigs, leaves, stones and bird droppings. The function of masquerade in prey species is clear: predators misclassify masquerading prey as the inedible objects they resemble and consequently they avoid being eaten. However it is unclear why masquerade is found in predatory species. Here I present the results of a series of experiments that test the idea masquerade functions to enhance prey capture success in predators by causing prey to misclassify masquerading predators as the innocuous items they resemble.

Colour change and camouflage in rockpool fish Sam Smithers University of Bristol The ability to change colour and pattern for camouflage is likely to provide a survival advantage for animals living in highly heterogeneous habitats such as rockpools. I will talk about the ability of the rock goby (Gobius paganellus) to change its colour, luminance, and body pattern in response to changes in its visual background. The findings show that some background colours and brightness are easier to match than others and that this may be the result of asymmetries in selection pressure to match different backgrounds. The findings also demonstrate that rock gobies change their body pattern in response to their background. Their pattern, when expressed, is characteristic of disruptive coloration and thus may function by destroying the visual outline of the animal. This may be particularly important given that predators are thought to use edge information and body outline, rather than colour, when searching for targets in complex habitats.

Predator Learning about Aposematism in Striped Skunks Theodore Stankowich California State University Long Beach Bold aposematic patterns are easy to learn and recognize, promoting pattern uniformity within and between species facing the same predator, as minimal variation in signal reduces attack mistakes. Individuals of some aposematic species, however, show great individual variation in coloration, despite theory predicting the opposite. We conducted behavioral trials on captive coyotes using aposematic noxious spraying models of striped skunks (Mephitis mephitis), which exhibit extensive natural variation in pelage, to study variation in “innateness” of aposematic avoidance, speed of learning, and ability to generalize to variant patterns. We found extreme variation in initial avoidance of the novel aposematic models, that most subjects learned to avoid spraying models after only being sprayed 1-2 times, and that coyotes could generalize this avoidance to similar stripe patterns but not extreme variants. We suggest that experience is necessary for coyote avoidance of skunks and that variation in predator learning may drive variation in pattern.

Using online Easter egg hunts to study camouflage Martin Stevens University of Exeter There are many relatively untested ideas for how camouflage works and evolves, including how matching is optimised in different habitat types. A common approach is to design artificial ‘prey’ with specific properties to test how camouflage works and its value. An alternative, however, is to create artificial simulations with evolving populations of prey under different contexts. We created an online ‘citizen science’ computer game with human ‘predators’ searching for computer- generated eggs with different colours and markings. As the game progressed through egg generations, the surviving eggs could evolve and mutate, allowing us to study what types of camouflage arise against different types of visual background and with different levels of patch specialisation by the eggs. Results show how different types of camouflage (disruption and background matching) evolve, their properties, and have implications for understanding compromise and specialist types of camouflage in heterogeneous environments.

Occurrence and function of iridescence in Heteroptera Pavel Stys Department of Zoology, Charles University in Prague Iridescent colours result from the reflection of light from superimposed surfaces with different refractive indices, which leads either to reinforcement or cancelling out particular wavelengths. The of reflected light depends on spacing, and changes with viewing angle. Iridescence is rare in Heteroptera of temperate Europe (<0.5% taxa) but common in some taxa in tropics. It is rather frequent among the Pentatomomorpha of central Afrotropis in the families Scutelleridae, Pentatomidae, Tessarotomidae, Plataspidae, and Coreidae. The iridescent areas may spread over the whole body or be restricted to smaller areas. Iridescence is often combined with a conspicuous orange or red colours (pterines) and black melanic patterns. However, in some taxa the iridescent patches form part of a brownish-greenish coloration. Iridescent coloration can be an effective aposematic signal, and probably plays a role in as well. Supported by Synthesys BE-TAF1313 to PŠ.

Evidence for (lack of) honest signalling in a poison frog Kyle Summers East Carolina University Signaling is an important part of intraspecific and interspecific interactions. Honest signaling has largely been studied under the umbrella of , however interest in honest signaling in the context of aposematism is increasing. Theoretical work examining honest signaling in aposematic species has primarily focused on patterns within populations. However, most empirical work has investigated patterns across populations or species. Here we test for honest signaling across individuals within a population of the aposematic poison frog, Ranitomeya imitator. We find no evidence that increasing levels of the aposematic signal are correlated with increasing levels of defense in this species, indicating that this population does not signal in a quantitatively honest manner. Additionally, we found no evidence that more toxic frogs behave more boldly as a result of increased ecological release from predation. We discuss alternative mechanisms that may mediate the relationship between toxicity and the aposematic signal in this system.

Quantifying camouflage: how to predict detectability from appearance Jolyon Troscianko University of Exeter Quantifying the conspicuousness of objects against particular backgrounds is key to understanding the evolution and adaptive value of animal coloration, and in designing camouflage patterns for humans. Quantifying detectability can reveal how colour patterns affect survival, how animals’ appearances influence habitat preferences, and how receiver visual systems work. Numerous descriptions and models of appearance have been used to infer the detectability of animals, but it is often unclear how well these measures predict behavioural detectability; models are rarely empirically validated or directly compared to one another. We used humans as ‘predators’ in a touch-screen computer experiment to determine which method of quantifying the appearance of camouflaged ‘prey’ best predicted detection times. We assessed several established methods and developed a new method for measuring disruptive coloration based on an understanding of sensory processing. This novel measure was the best predictor of detection times, demonstrating the importance of false edges in concealment. While our results validate the use of some established methods, they suggest others may perform badly. More broadly, our findings demonstrate how properly validated methods of quantifying signals can illuminate our understanding of how patterns exploit receiver visual systems, and why animals possess the patterns seen in nature.

Avoiding attack: The need for speed Diana Umeton University of Calabria-Newcastle University Aposematic and camouflaged prey need to move. Movement, particularly for camouflaged prey, is likely to be costly: movement can ‘break’ camouflage. In contrast, movement could be beneficial to aposematic prey, whose patterns are highly conspicuous when stationary, but may blur together or ‘dazzle’ predators when moving: this makes them hard to track and capture. Currently, we don’t know if these effects are speed-dependent, or how speed of movement interacts with visual pattern. I will explore how these two factors interact by measuring how praying mantids track computer generated stimuli presented on a screen. I aim to highlight the importance of considering prey movement in the evolution and efficacy of defensive coloration.

Marine butterflies: a putative mimicry ring in nudibranch molluscs Anne Winters The University of Queensland Nudibranch molluscs can be considered ‘butterflies of the sea’ in terms of their conspicuous colourful displays and sequestered chemical defences. Here we investigate a putative mimicry ring through objective analysis of colour pattern convergence in 11 co-occuring species. We examine spectral reflectance and pattern geometry, assess shared ancestry through phylogenetic analysis, identify and quantify defensive metabolites, and measure defences using palatability and toxicity assays. We show that these species display similar visual characteristics (in terms of colour and pattern) compared to other closely related species. We also show that defensive metabolites differ among these species, and that these compounds vary in the level of defence they provide. We propose this nudibranch group as an example of a quasi-batesian mimicry ring. This comprehensive study is the first quantitative analysis of nudibranch defensive mimicry, and sheds light on the mechanisms that drive the evolution of colour patterns in these colourful marine molluscs.

Primate camouflage in the eyes of felids, raptors, and conspecifics Sandra Winters New York University Animal coloration has diverse functions, from mate attraction to predator avoidance. A common form of anti-predator coloration is the exhibition of colors similar to environmental backgrounds to create camouflage. Here, we assess background matching in primates using visual models depicting how primate colors are seen by dichromatic felid predators, trichromatic conspecifics, and tetrachromatic raptor predators. Using reflectance spectra from 79 primate species and 399 plant species, we plotted colors in multi-dimensional color spaces and tested for and body part effects using phylogenetically-controlled mixed models. We found that primate and background colors overlap greatly, leaving vast areas of visual space unused. Primate colors show increased background matching for felids compared to raptors and conspecifics, but no significant difference between raptors and conspecifics. Primate backs, caps, and tails contrast most with the background, and bellies least. Our study suggests new insights into the selective pressures that have shaped primate appearance.

Non-presenting attendees Craig Barnett, Kyoto University Ian Chan, National University of Singapore James Higham, New York University Victoria Lee, University of Exeter Sam Machette, University of Bristol Konstantinos Michalis, University of Bristol William Resetartis, University of Mississippi Nicholas Roberts, University of Bristol Alice Rosen, University of Exeter

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