Jolyon Troscianko

Jolyon Troscianko
University of Exeter | UoE · College of Life and Environmental Sciences

PhD

About

129
Publications
29,139
Reads
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1,840
Citations
Additional affiliations
January 2017 - present
University of Exeter
Position
  • Fellow
Description
  • NERC IRF on Camouflage and the Light Environment
January 2013 - December 2016
University of Exeter
Position
  • PostDoc Position
September 2007 - September 2011
University of Birmingham
Position
  • PhD Student
Description
  • Ecological, morphological and behavioural aspects of tool-use in New Caledonian Crows

Publications

Publications (129)
Article
Full-text available
Quantitative measurements of colour, pattern and morphology are vital to a growing range of disciplines. Digital cameras are readily available and already widely used for making these measurements, having numerous advantages over other techniques, such as spectrometry. However, off‐the‐shelf consumer cameras are designed to produce images for human...
Article
Full-text available
Evading detection by predators is crucial for survival. Camouflage is therefore a widespread adaptation, but despite substantial research effort our understanding of different camouflage strategies has relied predominantly on artificial systems and on experiments disregarding how camouflage is perceived by predators. Here we show for the first time...
Article
Understanding the adaptive function of conspicuous coloration has been a major focus of evolutionary biology for much of the last century. Although considerable progress has been made in explaining how conspicuous coloration can be used in functions as diverse as sexual and social signaling, startling predators, and advertising toxicity [1], there...
Article
Full-text available
To understand the function of colour signals in nature, we require robust quantitative analytical frameworks to enable us to estimate how animal and plant colour patterns appear against their natural background as viewed by ecologically relevant species. Due to the quantitative limitations of existing methods, colour and pattern are rarely analysed...
Article
Full-text available
Ornaments used in courtship often vary wildly among species, reflecting the evolutionary interplay between mate preference functions and the constraints imposed by natural selection. Consequently, understanding the evolutionary dynamics responsible for ornament diversification has been a longstanding challenge in evolutionary biology. However, comp...
Article
Full-text available
Egg rejection is a crucial defence strategy against brood parasitism that requires the host to correctly recognise the foreign egg. Rejection behaviour has, thus, evolved in many hosts, facilitated by the visual differences between the parasitic and host eggs, and driving hosts to rely on colour and pattern cues. On the other hand, the need to reco...
Article
Eyes convey important information about the external and internal worlds of animals. Individuals can follow the gaze of others to learn about the location of salient objects as well as assess eye qualities to evaluate the health, age or other internal states of conspecifics. Because of the increasing prevalence of artificial lighting at night (ALAN...
Article
Full-text available
Eye gaze is an important source of information for animals, implicated in communication, cooperation, hunting and antipredator behaviour. Gaze perception and its cognitive underpinnings are much studied in primates, but the specific features that are used to estimate gaze can be difficult to isolate behaviourally. We photographed 13 laboratory-hous...
Article
Full-text available
Chimpanzee (Pan troglodytes) sclera appear much darker than the white sclera of human eyes, to such a degree that the direction of chimpanzee gaze may be concealed from conspecifics. Recent debate surrounding this topic has produced mixed results, with some evidence suggesting that (1) primate gaze is indeed concealed from their conspecifics, and (...
Article
Full-text available
Camouflage research has long shaped our understanding of evolution by natural selection, and elucidating the mechanisms by which camouflage operates remains a key question in visual ecology. However, the vast diversity of colour patterns found in animals and their backgrounds, combined with the scope for complex interactions with receiver vision pr...
Preprint
An object's colour, brightness and pattern are all influenced by its surroundings, and a number of visual phenomena and "illusions" have been discovered that highlight these often dramatic effects. Explanations for these phenomena range from low-level neural mechanisms to high-level processes that incorporate contextual information or prior knowled...
Article
Full-text available
The sun is the most reliable celestial cue for orientation available to daytime migrants. It is widely assumed that diurnal migratory insects use a ‘time-compensated sun compass’ to adjust for the changing position of the sun throughout the day, as demonstrated in some butterfly species. The mechanisms used by other groups of diurnal insect migrant...
Article
Full-text available
Individual identification is crucial for studying animal ecology and evolution. In birds this is often achieved by capturing and tagging. However, these methods are insufficient for identifying individuals/species that are secretive or difficult to catch. Here, we employ an automatic analytical approach to predict the identity of bird females based...
Article
Full-text available
The nighttime environment is being altered rapidly over large areas worldwide through introduction of artificial lighting, from streetlights and other sources. This is predicted to impact the visual ecology of many organisms, affecting both their intra- and interspecific interactions. Here, we show the effects of different artificial light sources...
Article
Full-text available
Parallel evolution, in which independent populations evolve along similar phenotypic trajectories, offers insights into the repeatability of adaptive evolution. Here, we revisit a classic example of parallelism, that of repeated evolution of brighter males in the Trinidadian guppy (Poecilia reticulata). In guppies, colonisation of low predation hab...
Article
Full-text available
Understanding what maintains the broad spectrum of variation in animal phenotypes and how this influences survival is a key question in biology. Frequency dependent selection – where predators temporarily focus on one morph at the expense of others by forming a “search image” – can help explain this phenomenon. However, past work has never tested r...
Article
Full-text available
The motion dazzle hypothesis posits that high contrast geometric patterns can cause difficulties in tracking a moving target and has been argued to explain the patterning of animals such as zebras. Research to date has only tested a small number of patterns, offering equivocal support for the hypothesis. Here, we take a genetic programming approach...
Preprint
Full-text available
Identification of individuals greatly contributes to understanding animal ecology and evolution, and in many cases can only be achieved using expensive and invasive techniques. Advances in computing technology offer alternative cost-effective techniques which are less invasive and can discriminate between individuals based on visual and/or acoustic...
Preprint
Parallel evolution, in which independent populations evolve along similar phenotypic trajectories, offers insights into the repeatability of adaptive evolution. Here, we revisit a classic example of parallelism, that of repeated evolution of brighter males in the Trinidadian guppy. In guppies, colonisation of low predation habitats is associated wi...
Cover Page
Full-text available
The grass finches (family Estrildidae) are the host family to the brood-parasitic indigobirds and whydahs (genus Vidua). They are unusual among birds in having highly ornamentedand diverse nestlings. On pages 2526–2538, Jamie et al. provide quantitative evidence that many of these colours and patterns are by nestling Vidua parasites. First and seco...
Preprint
Full-text available
Forests are a mosaic of light spectra, and colour signal efficiency might change in different light environments. Local adaptation in Heliconius butterflies is linked to microhabitat use and the colourful wing colour patterns may be adapted for signalling in different light environments. These toxic butterflies exhibit conspicuous colours as a warn...
Article
Full-text available
Sexually selected ornaments range from highly dynamic traits to those that are fixed during development and relatively static throughout sexual maturity. Ornaments along this continuum differ in the information they provide about the qualities of potential mates, such as their parasite resistance. Dynamic ornaments enable real-time assessment of th...
Article
Full-text available
Brood parasites use the parental care of others to raise their young and sometimes employ mimicry to dupe their hosts. The brood‐parasitic finches of the genus Vidua are a textbook example of the role of imprinting in sympatric speciation. Sympatric speciation is thought to occur in Vidua because their mating traits and host preferences are strongl...
Article
Vision is the dominant sense for many animals, and there is an enormous diversity in visual capabilities. Understanding the visual abilities of a given species can therefore be key for investigating its behaviour and evolution. However, many techniques for quantifying visual capability are expensive, require specialized equipment, or are terminal f...
Article
Full-text available
In the animal kingdom, conspicuous colors are often used for inter- and intra-sexual communication. Even though primates are the most colorful mammalian taxon, many questions, including what potential information color signals communicate to social partners, are not fully understood. Vervet monkeys (Chlorocebus pygerythrus) are ideal to examine the...
Preprint
Full-text available
The motion dazzle hypothesis posits that high contrast geometric patterns can cause difficulties in tracking a moving target, and has been argued to explain the patterning of animals such as zebras. Research to date has only tested a small number of patterns, offering equivocal support for the hypothesis. Here, we take a genetic programming approac...
Article
Full-text available
One of the most effective defensive strategies of hosts against brood parasites is rejection, commonly achieved by ejection of the parasitic egg or desertion of the parasitized nest. Nest desertion should be a costlier strategy than egg ejection, because birds must thesn spend additional time and energy renesting, and therefore we still cannot expl...
Article
The seemingly transparent wings of many insects have recently been found to display unexpected structural coloration. These structural colours (wing interference patterns: WIPs) may be involved in species recognition and mate choice, yet little is known about the evolutionary processes that shape them. Furthermore, to date investigations of WIPs ha...
Article
Full-text available
Camouflage is a key defence across taxa and frequently critical to survival. A common strategy is background matching, resembling the colour and pattern of the environment. This approach, however, may be ineffective in complex habitats where matching one patch may lead to increased visibility in other patches. In contrast, disruptive coloration, wh...
Preprint
Full-text available
To understand the function of colour signals in nature, we require robust quantitative analytical frameworks to enable us to estimate how animal and plant colour patterns appear against their natural background as viewed by ecologically relevant species. Due to the quantitative limitations of existing methods, colour and pattern are rarely analysed...
Preprint
Full-text available
The seemingly transparent wings of many insects have recently been found to display dramatic structural coloration. These structural colours (wing interference patterns: WIPs) may be involved in species recognition and mate choice, yet little is known about the evolutionary processes that shape them. Additionally, existing research has been restric...
Data
Species-specific courtship phenotype estimates. (XLS)
Data
Species-specific behavioral richness estimates from different sliding-window sizes (10 s–60 s). (XLS)
Data
Summary of specimens located at the American Museum of Natural History used to quantify color complexity in the birds-of-paradise. (DOCX)
Data
mPGLS analyses of communication-relevant influences on three axes of courtship phenotype diversity conducted only on species without imputed species level values. mPGLS, multiple phylogenetic generalized least squares. (DOCX)
Data
ImageJ plugin (java) for hierarchical clustering using chromatic and achromatic JNDs. JND, Just Noticeable Distance. (JAVA)
Data
Species-specific behavioral diversity estimates from different sliding-window sizes (10 s–60 s). (XLS)
Data
Species-specific acoustic diversity estimates from different sliding-window sizes (5 s–50 s). (XLS)
Data
Partial summary (PC1–PC3) of PCA of 5739 notes produced by 32 bird-of-paradise species. PC loadings for PC1–PC3 were used to plot notes in three-dimensional PCA space prior to agglomerative hierarchical clustering based on Euclidean distances to categorize notes. PC, principal component; PCA, principal component analysis. (DOCX)
Data
mPGLS analyses of communication-relevant influences on three axes of courtship phenotype richness conducted only on species without imputed species level values. mPGLS, multiple phylogenetic generalized least squares. (DOCX)
Data
Accumulation of unique behaviors plateaus by time windows of approximately 50 s for most species. Note, these are unique behaviors per individual (not per clip). This distinction is important because some individuals were recorded in several clips, but in the longer clips they might not be doing much behaviorally (leading to the initially surprisin...
Data
Pairwise comparisons of behavioral richness (number of unique behaviors) estimates for windows between 10 and 60 s in duration. Within plots, each point represents a species in the family Paradisaeidae, with species-specific values obtained from rphylopars reconstructions incorporating intra- and interspecific variation. Best-fit lines in lower plo...
Data
Dorsal view of raw (left side) and clustered (right side) images taken of a Wilson’s bird-of-paradise. Following clustering based on chromatic and achromatic thresholds (see Methods), every pixel in every image is assigned to a categorical color identity. The total number of colors in an image provides a measure of richness, and the numbers equival...
Data
Bird-of-paradise behavioral scoring demonstration. In this video, a male western parotia Parotia sefilata performs a species-typical courtship dance for females perching above. This video demonstrates the concordance between a subsample of our scored behaviors and the actual performance of the bird in real-time. The behaviors represent BP1, BP2, SS...
Data
Species-specific acoustic richness estimates from different sliding-window sizes (5 s–50 s). (XLS)
Data
Species sampled for courtship behavior, including the number of individuals watched. (DOCX)
Data
Species sampled for acoustic courtship complexity, including the number of individuals analyzed. (DOCX)
Data
Pairwise comparisons of acoustic diversity (log transformed Shannon indices of acoustic complexity) estimates for windows between 5 and 50 s in duration. Within plots, each point represents a species in the family Paradisaeidae, with species-specific values obtained from rphylopars reconstructions incorporating intra- and interspecific variation. B...
Data
mPGLS analyses of communication-relevant influences on three axes of courtship phenotype diversity. Categorical comparisons of display site are made with respect to ground-displaying birds, and breeding system comparisons are made with respect to solitarily displaying birds. mPGLS, multiple phylogenetic generalized least squares. (DOCX)
Data
mPGLS analyses of communication-relevant influences on three axes of courtship phenotype richness. Categorical comparisons of display site are made with respect to ground-displaying birds, and breeding system comparisons are made with respect to solitarily displaying birds. mPGLS, multiple phylogenetic generalized least squares. (DOCX)
Data
Ethogram describing behavioral subunits scored while observing courtship display behavior of birds-of-paradise. (DOCX)
Data
mPGLS analyses of communication-relevant influences on three axes of courtship phenotype diversity conducted using behavioral complexity metrics from a 10 s and a 60 s time window. For comparison, the analyses presented in the main text focus on behavioral complexity estimated from a 50 s time window. mPGLS, multiple phylogenetic generalized least...
Data
mPGLS analyses of communication-relevant influences on three axes of courtship phenotype richness conducted using behavioral complexity metrics from 10 s and 60 s time windows. The analyses presented in the main text focus on behavioral complexity estimated from a 50 s time window. mPGLS, multiple phylogenetic generalized least squares. (DOCX)
Data
There is no evidence for correlated evolution between color and behavioral diversity among birds-of-paradise. mPGLS regression reveals no significant relationship between behavioral and color diversity when controlling for acoustic diversity, display height, and display proximity. This plot is a phylo-signal-space plot in which species ornamentatio...
Data
Pairwise comparisons of behavioral diversity (Shannon indices of behaviors) estimates for windows between 10 and 60 s in duration. Within plots, each point represents a species in the family Paradisaeidae, with species-specific values obtained from rphylopars reconstructions incorporating intra- and interspecific variation. Best-fit lines in lower...
Data
Accumulation of unique notes plateaus at time windows of approximately 10 s for most species. (DOCX)
Data
Pairwise comparisons of acoustic richness (number of unique note types) estimates for windows between 5 and 50 s in duration. Within plots, each point represents a species in the family Paradisaeidae, with species-specific values obtained from rphylopars reconstructions incorporating intra- and interspecific variation. Best-fit lines in lower plots...
Data
Table S1. Biorepository ID for bird samples used archived in the Smithsonian Tropical Research Institute Cryological Collection in Panama and accession number for the SWS1 opsin gene at GenBank. Table S2. One‐way ANOVA (with individuals as random factors) results for chromatic JND comparisons between co‐mimics and conspecifics for Figure 1. Table...
Article
Full-text available
Numerous animals rely on camouflage for defence. Substantial past work has identified the presence of multiple strategies for concealment, and tested the mechanisms underpinning how they work. These include background matching, D-RUP coloration to destroy target edges, and distractive markings that may divert attention from key target features. Des...
Article
Full-text available
Adaptive coloration is under conflicting selection pressures: choosing potential mates and warning signalling against visually guided predators. Different elements of the colour signal may therefore be tuned by evolution for different functions. We investigated how mimicry in four pairs of Heliconius co‐mimics is potentially seen both from the pers...
Article
Full-text available
The Common Cuckoo (hereafter Cuckoo) shows two adult plumage morphs—adult male plumage is grey and adult females are either grey or, less frequently, rufous. The situation is less clear in juveniles, as both sexes exhibit variable proportions of grey and rufous colour. We thus describe the patterns related to sex-specific plumage colour variation i...
Article
Full-text available
Camouflage is a widespread strategy to avoid predation and is of particular importance for animals with reduced mobility or those in exposed habitats. Camouflage often relies on matching the visual appearance of the background, and selecting fine-scale backgrounds that complement an individual’s appearance is an effective means of optimising camouf...