Download Anti-Predator Coloration Symposium

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 camouflage and startle displays to warning
signals and mimicry. Research 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 Natasha ([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 animal life histories, group
behaviour, reproductive biology, signalling and communication, sensory ecology, 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);
Lizard 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 Green and Yellow. 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. We will ask some attendees to help run these.
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 15th 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
9.30-9.55: Talk session 1: Aposematism 1 – Warning signal diversity
Chair: Anne Winters
Lina Maria Arenas
Be together but not the same: diversity as a strategy to increase warning signal
effectiveness
Katja Rönkä
Role of predation in geographic vs. local variation in the warning coloration of an
aposematic moth
Emily Burdfield-Steel
Truth and Lies: not quite honest signalling in an aposematic moth
10.00-10.25: Talk session 2: Aposematism 2 – Warning signal evolution
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 skunks
10.30-11.00: Coffee break
11.00-11.25: 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 lizards enhances camouflage against avian predators
Sandra Winters
Primate camouflage in the eyes of felids, raptors, and conspecifics
11.30-11.55: Talk session 4: Camouflage 2 – Disruptive colouration
Chair: Will Allen
Jolyon Troscianko
Does disruptive camouflage disrupt search image formation?
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
Sarah Paul
Eggscellent defence strategies – the role of maternal effects in ladybird laying strategies
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 butterfly by wild birds in a tropical forest
Sam Green
Fluorescent froth frightens feathered foes
Thomas Schultz
The role of iridescent colors in predator avoidance strategies
4.30-4.50: Talk session 8: Vision and methods
Chair: Carita Lindstedt-Kareksela
Johanna Mappes
Individual variation and colour perception
Julien Renoult
Methods of quantifying visual dissimilarity between colour patterns
4.50-5.00: 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 9: Camouflage and colour change 1
Chair: Kate Marshall
Ossi Nokelainen
Phenotype-environment associations in the green shore crab (Carcinus maenas)
Rafael Duarte
Camouflage efficiency in Hippolyte prawns: how to survive in a multi-coloured habitat?
Jennifer Easley
Colour change in the shore crab
Sara Mynott
Colour change and camouflage in lobsters, and implications for their conservation
9.40-10.05: Talk session 10: Camouflage and colour change 2
Chair: Kate Marshall
Roger Hanlon
Rapid adaptive camouflage in cephalopods
Sam Smithers
Colour change and camouflage in rockpool fish
Natasha Price
Patterned background matching through moulting in European green shore crabs
10.10-10.35: Talk session 11: Multifunctionality of colour and pattern changes
Chair: Kate Marshall
Will Allen
Evolution of color 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 12: Aposematism 5 – Signal honesty
Chair: Sarah Paul
Emmanuelle Briolat
Honesty in aposematic signalling: colour and toxicity in burnet moths
Kyle Summers
Evidence for (lack of) honest signalling in a poison frog
Carita Lindstedt-Kareksela
Hidden honest signals of unpalatability?
11.40-12.05: Talk session 13: Batesian mimicry
Chair: Sarah Paul
Innes Cuthill
Eyespots: eye mimicry or just conspicuous?
Karin Kjernsmo
Resemblance to the enemy’s eyes underlies the adaptive function of intimidating eyespots
Casey Peet-Paré
Hoverfly mimicry in the ultraviolet
12.10-12.35: Talk session 14: Evolution and theory
Chair: Sarah Paul
Anne Winters
Marine butterflies: 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 signals and mimicry
Ted Stankowich & Brett Seymoure
3.00-3.30: Coffee break
3.30-3.55: Talk session 15: Multifunctional signals and camouflage
Chair: Sam Smithers
Tom Cronin
The other color: dealing with predators in polarized light
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 16: Movement and dazzle camouflage 1
Chair: Sam Smithers
Benedict Hogan
Dazzle camouflage, target tracking and the confusion effect
Joanna Hall
Dazzle under stress
Diana Umeton
Avoiding attack: the need for speed
4.30-4.55: Talk session 17: Movement and dazzle camouflage 2
Chair: Sam Smithers
Nick Scott-Samuel
Colouration, oddity and confusion
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, mammals, 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 habitats, 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 emergence 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 hummingbirds. 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.).
Be together, but not the same: diversity as a strategy to increase warning signal
effectiveness
Lina Maria Arenas
University of Cambridge/University of Exeter
Warning coloration is a widespread strategy to alert predators about prey unprofitability. Its
success depends on predators learning and recognising colours as indicators of toxicity, and
theory predicts that this is easier if signals converge into similar signal forms. However, the
diversity in warning signals is astonishing, contradicting predictions from theoretical work. We
quantified ladybird signal diversity with respect to predator vision, predicting that similar signals
would be grouped into phenotypic clusters aiding predator recognition and avoidance. However,
we found that ladybird signals are unique and easily distinguishable from each other. In addition,
all signals are highly contrasting against natural backgrounds, although habitat use might explain
some differences in conspicuousness. We show that highly effective signals may allow the
evolution of varied signal forms by maintaining honest signalling strategies among species.
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-black 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.
Honesty in aposematic signalling: colour and toxicity in burnet moths
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 moths (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 resource limitation and artificial predation trials in the field. Together, these
experiments explore natural variation in burnet moth colouration, how this relates to toxin levels
and ultimately affects predator behaviour.
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 tiger 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 red, with red providing the stronger anti-predator signal. We presented defensive fluids
from female moths to wild blue-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 mantis 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 bird 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 chameleon 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 white) 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 phenotype-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
Octopus, squid and cuttlefish 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 lions. 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 adaptation, 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
natural selection 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.
Hidden honest signals of unpalatability?
Carita Lindstedt-Kareksela
University of Jyväskylä
Social pinesawfly species perform defensive group-rearing and regurgitation behavior during the
larval stage. Larvae are unpalatable and their coloration varies from polymorphic aposematic
(Neodiprion lecontei) to nearly cryptic (Neodiprion sertifer and Diprion pini). Common feature for all
of these species is the defensive display of larvae: when threatened, they raise their head and tail
for the U-shaped posture and regurgitate resinous fluid from their mouth. Vision models suggest
that especially the ventral side of the N. sertifer larvae is highly visible for birds in terms of
achromatic contrast against various backgrounds. In addition, the brightness of the ventral side
correlates positively with the quantity of defensive fluid larvae regurgitate both in N. lecontei and N.
sertifer species. Bright ventral side revealed in U-posture together with the regurgitation and
display of defensive fluid may then function as a hidden signal that honestly warns predators of
secondary defenses of prey.
Individual variation and colour perception
Johanna Mappes
University of Jyväskylä
Visual perception, in particular that of color, is a challenging, yet vital, task for researchers
interested in the evolution of animal communication. Recently, many important methodological
innovations and developments have been done, yet the area is still suffering from a lack of an
integrated approach i.e. combining the information of physiology and behavioural response of
animals (rev. Kemp et al. 2015). Although many useful indirect methods e.g. tools for modelling the
perception, have been developed, selection still acts through the behavioural responses alone.
The ability of an organism to distinguish between different colours is irrelevant unless it actually
uses that information to guide its responses. Another important point is that although our
understanding of how animals perceive the world has improved over recent decades, we must next
understand how this perception can vary, not just between species, but also within them. If there is
indeed individual variation within species, our estimates of their visual capabilities may be
misleading. Ultimately, individual variation is the raw material for natural selection, and thus a key
ingredient to our understanding of perception as an adaptation. In my presentation, I will go
through some methodological developments in the study of perception. I will discuss how
researchers working in the area should address these issues if our vision of a more integrated field
is to be realised.
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 adaptations 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.
Colour change and camouflage in lobsters, and implications for their conservation
Sara Mynott
University of Exeter
Many animals change colour for camouflage, but the applied benefits of this are only just being
realised. Following crashes in European lobster (Homarus gammarus) populations in Scandinavia
and local declines across Europe, hatcheries were established to help enhance localised lobster
stocks. Juvenile lobsters are reared through the most vulnerable stages before being released into
the wild. Research has focussed on releasing healthy juveniles into suitable habitats, but little
consideration has been given to matching individuals to their release site. Working with the
National Lobster Hatchery, we have identified the potential for altered hatchery housing to enhance
cryptic coloration in reared lobsters. By allocating individuals to different backgrounds and
quantifying changes in their appearance through image analysis, lobster camouflage can be
modelled to predator vision. Early results indicate that background-matching could be used to
enhance juvenile survival on release, with the potential to benefit both lobster conservation and
fisheries.
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.
Phenotype-environment associations in the green shore crab (Carcinus maenas)
Ossi Nokelainen
Centre for Ecology and Conservation, University of Exeter
In rock pools along coastline of the North Sea, one may come across well-concealed, yet strikingly
variable shore crabs. The green shore crab (Carcinus maenas) blends effectively into its
background by its coloration. The carapace colour varies substantially (e.g. green, brown, orange)
and also shows a highly variable patterning (including black or white markings). Here, I explore
phenotype-environment associations of shore crabs using an integrated approach of digital
photography and vision modelling techniques. Studying the range of variation in the shore crab
patterning is important especially in the light of vision systems of relevant predators (e.g. birds and
fish), because it will illuminate our understanding on how animals optimise their camouflage 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
Hoverflies (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.
Adaptive pattern changes in the common shore crab
Natasha Price
University of Exeter
The ability to change appearance to match variation in an environment is an invaluable survival
strategy for animals facing high predation risk. Common shore crabs (Carcinus maenas) regularly
become exposed at low tide, making them vulnerable to predation. Despite this, there have been
few studies to explore the camouflage abilities of shore crabs and even fewer to quantify their
phenotypic plasticity. Recent research has shown that shore crabs alter their brightness in
response to a white or black background, providing a means of camouflage through background
matching. Here, we explore this background matching capability further, using patterned and
uniform backgrounds to assess whether shore crabs develop or lose patterns over a period of 12
weeks in relation to their artificial background. Using model visual systems of shore crab predators,
we use image analysis techniques to quantify carapace pattern change whilst providing an
accurate representation of prey concealment across different backgrounds.
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 animal coloration including
signalling traits and colour patterns important for camouflages. 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 plumage 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 ongoing 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 hues with bright complementary pigments 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 computergenerated 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
hue 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 pigment 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 crypsis 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 sexual selection, 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.
Does Disruptive Camouflage Disrupt Search Image Formation?
Jolyon Troscianko
University of Exeter
The effectiveness of any camouflage strategy depends on both the interaction between the prey's
appearance against it's background and the predator's cognition. For example, forming a search
image for one prey type should detriment a predator's ability to switch to another. We investigated
whether human and chicken 'predators' could switch from one camouflage type as readily as
another after they had formed a search image. Our initial results show that it was easier to switch
to background matching prey after forming a search image for disruptive prey than vice-versa,
suggesting disruptive camouflage prevents successful search image formation. However, we found
no differences in performance when subjects were prevented from forming an initial search image.
The effect of learning on camouflage type could dramatically affect predator-prey relationships and
camouflage evolution. To our knowledge this is the first study to investigate the effect of search
image formation between discrete camouflage strategies.
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 visual system 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
Changku Kang, Carleton University
Victoria Lee, University of Exeter
Sam Machette, University of Bristol
Jenna Proctor, University of Exeter
William Resetartis, University of Mississippi
Nicholas Roberts, University of Bristol
Alice Rosen, University of Exeter
Campus map