Papers by Devi Stuart-fox
Individual and pooled performance of bees during the learning phase in experiment 1. Black crosse... more Individual and pooled performance of bees during the learning phase in experiment 1. Black crosses indicate pooled data for all bees (n = 10) in the unrestricted viewing condition (means ± SEM). Dashed coloured lines represent each individual bee's performance over the 80 conditioned trials. Dashed line at 0.5 indicates the chance level performance.
Figures S1-S2. Show effect of testosterone application on throat colour expression of mature fema... more Figures S1-S2. Show effect of testosterone application on throat colour expression of mature females and juveniles, respectively. Figure S3. Shows proportional coverage of each colour element in yellow (Y) versus OY morphs in the 56 adult males. Table S1. Presents pedigree of fifty-eight offspring across two breeding seasons used to assess models for inheritance. Table S2. Presents characteristics of microsatellite loci based on 70 unrelated wild-caught adults. (PDF 9495Â kb)
There are many factors that affect signal design, including the need for rapid signal detection a... more There are many factors that affect signal design, including the need for rapid signal detection and the ability to identify the signal as conspecific. Understanding these different sources of selection on signal design is essential to explain the evolution of both signal complexity and signal diversity. We assessed the relative importance of detection and recognition for signal design in the black-bearded gliding lizard, Draco melanopogon, which uses the extension and retraction of a large, black-and-white dewlap (or throat fan) in territorial communication. We presented free-living lizards with robots displaying dewlaps of different designs that varied in the proportion of the black and white components. We found no effect of dewlap brightness or design on the time it took for a lizard to detect the robot, consistent with the view that initial detection is likely to be primarily elicited by movement rather than specific color or pattern. However, males (but not females) responded with a greater intensity to the dewlap treatment that most resembled the natural dewlap color and design of the species. Furthermore, males were more likely to display to any dewlap color in the presence of a neighbor. These results suggest that dewlap pattern may play an important role in species recognition but has minimal influence on the initial detection of the signal. Importantly, our results also highlight that factors unrelated to discrimination, such as social cues and individual motivational state, may affect responses to species identity cues
Species Population/ Race Common Name Family Sex Latitude (Dec) Longitude (Dec) Date Collected LEP... more Species Population/ Race Common Name Family Sex Latitude (Dec) Longitude (Dec) Date Collected LEP3067 Mesodina aeluropis Montane Iris-skipper Hesperiidae 1 Unknown-33.63 150.28 04/11/1941 LEP3065 Mesodina aeluropis Montane Iris-skipper Hesperiidae 1 Unknown-33.63 150.28 LEP12611 Tisiphone abeona joanna rawnsleyi-morrisi hybrid Varied Sword-grass Brown Nymphalidae 3 Unknown-31.45 152.92 03/04/1918 LEP12551 Tisiphone abeona abeona Varied Sword-grass Brown Nymphalidae 4 Unknown-33.88 151.22 xx/10/1923 LEP12552 Tisiphone abeona abeona Varied Sword-grass Brown Nymphalidae 4 Unknown-33.88 151.22 25/10/1923 LEP12555 Tisiphone abeona abeona Varied Sword-grass Brown Nymphalidae 4 Unknown-33.88 151.22 24/10/1922 LEP12550 Tisiphone abeona abeona Varied Sword-grass Brown Nymphalidae 4 Unknown-33.88 151.22 xx/10/1923 LEP12549 Tisiphone abeona abeona Varied Sword-grass Brown Nymphalidae 4 Unknown-33.88 151.22 22/10/1922 LEP12677 Tisiphone abeona rawnsleyi Varied Sword-grass Brown Nymphalidae 5 Unknown-26.68 152.97 01/04/1923 LEP12678 Tisiphone abeona rawnsleyi Varied Sword-grass Brown Nymphalidae 5 Unknown-26.68 152.97 01/04/1923 LEP12676 Tisiphone abeona rawnsleyi Varied Sword-grass Brown Nymphalidae 5 Unknown-26.68 152.97 01/04/1923 LEP12679 Tisiphone abeona rawnsleyi Varied Sword-grass Brown Nymphalidae 5 Unknown-26.68 152.97 01/04/1923 LEP12684 Tisiphone abeona rawnsleyi Varied Sword-grass Brown Nymphalidae 5 Unknown-26.68 152.97 19/10/1922 LEP12672 Tisiphone abeona regalis Varied Sword-grass Brown Nymphalidae 6 Unknown-28.87 153.58 12/10/1902 LEP12665 Tisiphone abeona regalis Varied Sword-grass Brown Nymphalidae 6 Unknown-30.33
Functional Ecology, 2021
Some animals, including certain fish, beetles, spiders and Lepidoptera chrysalises, have such shi... more Some animals, including certain fish, beetles, spiders and Lepidoptera chrysalises, have such shiny or glossy surfaces that they appear almost mirror-like. A compelling but unsubstantiated hypothesis is that a highly specular or mirror-like appearance enhances survival by reflecting the surrounding environment and reducing detectability. We tested this hypothesis by asking human participants to wear a mobile eye-tracking device and locate highly realistic mirror-green and diffuse-green replica beetles against a variety of backgrounds in a natural forest environment. We also tested whether a mirror-like appearance enhances survival to wild predators by monitoring survival of mirror-green and diffuse-green replica beetles in a forested habitat and an open habitat. Human participants showed no difference in the detection probability or detection latency of mirror versus diffuse replica beetles, indicating that mirror-like appearance does not impair prey capture. The field predation experiment found no difference in survival between the mirror and diffuse replica beetles in forested environments. Similarly, there was no difference in survival when beetles were deployed in open habitat where there is no background to reflect, indicating that predators detect and do not actively avoid mirror-like beetles. Our results suggest that a mirror-like appearance does not reduce attack by predators. Instead, highly specular, mirror-like surfaces may have evolved for an alternate visual function or as a secondary consequence of selection for a non-visual function, such as thermoregulation.
Trends in Ecology & Evolution, 2021
Signals reliably convey information to a receiver. To be reliable, differences between individual... more Signals reliably convey information to a receiver. To be reliable, differences between individuals in signal properties must be consistent and easily perceived and evaluated by receivers. Iridescent objects are often striking and vivid, but their appearance can change dramatically with viewing geometry and illumination. The changeable nature of iridescent surfaces creates a paradox: how can they be reliable signals? We contend that iridescent color patches can be reliable signals only if accompanied by specific adaptations to enhance reliability, such as structures and behaviors that limit perceived hue shift or enhance and control directionality. We highlight the challenges of studying iridescence and key considerations for the evaluation of its adaptive significance. Iridescence and the Problem of Signal Reliability Iridescent objects are among the most vivid and visually striking in the natural world. For this reason, they are often assumed to be signals (see Glossary) that influence the behavior of receivers, whether they be predator, prey, competitor, or prospective mate. Iridescence, from the Greek word for rainbow (iridos) [1], describes a change in hue with viewing and/or illumination geometry (Figure 1). Because the appearance of iridescent objects can change dramatically in both space and time, iridescence can hamper the ability of animals to recognize objects in their environment [2-4], which is fundamental to most visual tasks, such as identifying food, enemies, or mates. The changeable nature of iridescent color patches poses a challenge for reliable signaling. How can information be reliably conveyed by signals that are inconsistent? Advances in our ability to quantify the dynamic nature of iridescence (e.g., through advanced spectroscopy, microscopy, multispectral imaging, and high-speed video [5-9]) have highlighted the prevalence, complexity, and diversity of iridescence, but its biological function remains an enigma. Unlike diffuse or matte colors, the appearance of iridescent color patches depends on when and how they are presented relative to the viewer; for example, how the signaler moves during display and/or how the viewer visually samples the target. Most studies of iridescence measure or consider only some of these factors. There are few cases where iridescence has been shown to convey specific information independent of the constituent hues (but see [5-7]). One problem in studies of iridescence is the pervasive inconsistency in how the term is used and how iridescence is measured. Iridescence is often confounded with structural coloration. Structural coloration arises from the interaction of light with physical structures at the microscopic scale and can produce complex, vivid colors and diverse optical effects such as white gloss, a metallic or mirror-like appearance, or polarized reflectance. Iridescence is just one of many optical effects produced by structural coloration. Sometimes, it is defined broadly to encompass angle-dependent changes in hue or intensity (luminance), because a change in intensity can cause a particular color to appear or disappear [1,10-14]. We advocate that iridescence be used exclusively to describe an angle-dependent change in hue, while specularity be used to describe the angle-dependent change in intensity. Although natural materials often show changes in both hue and intensity, the two properties are influenced by different structural
Ichthyology & Herpetology, 2021
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
Biological Journal of the Linnean Society, 2017
The benefits of colour change are expected to vary seasonally because of changes in reproductive ... more The benefits of colour change are expected to vary seasonally because of changes in reproductive activity, temperature and, potentially, predation risk; yet temporal variation in colour change has seldom been examined. We measured colour change in spring and autumn using captive individuals from two differently coloured populations of the central bearded dragon lizard, Pogona vitticeps. We predicted that colour change should be greater in spring than autumn because of the added requirements of reproductive and territorial activity. To elicit colour change in a standardized way, we placed lizards inside temperature-controlled chambers and measured colour at 15, 25, 35 and 40 °C, repeating experiments in spring and autumn. Lizards from both populations changed from dark grey to light yellowish or orange-brown (increasing luminance and saturation) with increasing temperature in both seasons, and both populations changed colour to a similar extent. As predicted, the maximal extent of temperature-induced colour change (in particular, luminance change) was greater in spring than autumn. Our results confirm that temperatureinduced colour change is greater in the peak activity season, probably an adaptation to the greater thermal and/or signalling needs of that time of year.
Biological Reviews, 2020
Time is a fundamental dimension of all biological events and it is often assumed that animals hav... more Time is a fundamental dimension of all biological events and it is often assumed that animals have the capacity to track the duration of experienced events (known as interval timing). Animals can potentially use temporal information as a cue during foraging, communication, predator avoidance, or navigation. Interval timing has been traditionally investigated in controlled laboratory conditions but its ecological relevance in natural environments remains unclear. While animals may time events in artificial and highly controlled conditions, they may not necessarily use temporal information in natural environments where they have access to other cues that may have more relevance than temporal information. Herein we critically evaluate the ecological contexts where interval timing has been suggested to provide adaptive value for animals. We further discuss attributes of interval timing that are rarely considered in controlled laboratory studies. Finally, we encourage consideration of ecological relevance when designing future interval‐timing studies and propose future directions for such experiments.
Current Zoology, 2020
Diversification in sexual signals is often taken as evidence for the importance of sexual selecti... more Diversification in sexual signals is often taken as evidence for the importance of sexual selection in speciation. However, in order for sexual selection to generate reproductive isolation between populations, both signals and mate preferences must diverge together. Furthermore, assortative mating may result from multiple behavioural mechanisms, including female mate preferences, male mate preferences and male-male competition; yet their relative contributions are rarely evaluated. Here, we explored the role of mate preferences and male competitive ability as potential barriers to gene flow between two divergent lineages of the tawny dragon lizard, Ctenophorus decresii, which differ in male throat coloration. We found stronger behavioural barriers to pairings between southern lineage males and northern lineage females than between northern males and southern females, indicating incomplete and asymmetric behavioural isolating barriers. These results were driven by both male and femal...
Functional Ecology, 2020
This is the author manuscript accepted for publication and has undergone full peer review but has... more This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record.
PLOS ONE, 2018
Research on the optical properties of animal integuments, including fur, feather, skin and cuticl... more Research on the optical properties of animal integuments, including fur, feather, skin and cuticle, has focussed almost exclusively on animal-visible wavelengths within the narrow range of 300-700 nm. By contrast, the near-infrared (NIR) portion of direct sunlight, spanning 700-2600 nm, has been largely ignored despite its potentially important thermal consequences. We quantified variation in visible and NIR reflectance and transmission for white body contour feathers of 50 bird species, and examined how well they are predicted by feather macro-and micro-structural morphology. Both visible and NIR reflectance of the feathers varied substantially across species. Larger, thicker, and sparser feathers that are characteristic of larger species, and feathers with rounder barbs and more closely spaced barbules, had high average reflectance, particularly within avian-visible wavelengths (300-700 nm). Feathers with rounder barbs and more closely situated barbules also had high average reflectance, particularly for NIR wavelengths. Barb roundness and barbule density were the only predictors of NIR reflectance after accounting for variation in visible reflectance and body size. Our results highlight the potential for adaptive variation in NIR reflectance mediated by feather structure, which may inform the design of functional materials to control light and heat.
Proceedings of the Royal Society B: Biological Sciences, 2019
Colour variation across climatic gradients is a common ecogeographical pattern; yet there is long... more Colour variation across climatic gradients is a common ecogeographical pattern; yet there is long-standing contention over underlying causes, particularly selection for thermal benefits. We tested the evolutionary association between climate gradients and reflectance of near-infrared (NIR) wavelengths, which influence heat gain but are not visible to animals. We measured ultraviolet (UVA), visible (Vis) and NIR reflectance from calibrated images of 372 butterfly specimens from 60 populations (49 species, five families) spanning the Australian continent. Consistent with selection for thermal benefits, the association between climate and reflectance was stronger for NIR than UVA–Vis wavelengths. Furthermore, climate predicted reflectance of the thorax and basal wing, which are critical to thermoregulation; but it did not predict reflectance of the entire wing, which has a variable role in thermoregulation depending on basking behaviour. These results provide evidence that selection fo...
Conservation Genetics, 2017
species. We found discordance between genetic markers, indicating historical mtDNA introgression ... more species. We found discordance between genetic markers, indicating historical mtDNA introgression at one of the study sites between P. cryodroma and the closely related, syntopic P. entrecasteauxii. Molecular diversity was positively associated with site elevation and extent of suitable habitat, with inbreeding detected in three of the five populations. These results demonstrate the complex interaction between geography and habitat in shaping the population structure and genetic diversity of P. cryodroma, and highlight the importance of minimising future habitat loss and fragmentation for the long-term persistence of this species.
Australian Journal of Zoology, 2017
Genetic mating systems described for squamate reptiles range from primarily monogamous to complet... more Genetic mating systems described for squamate reptiles range from primarily monogamous to completely polygynandrous. The presence of female multiple mating is almost ubiquitous among squamates and even occurs, albeit at a low rate, in socially monogamous species. Here we examine the genetic mating system of the territorial tawny dragon lizard (Ctenophorus decresii). Paternity was assigned to captive-born hatchlings using eight microsatellite loci, revealing a 4% rate of multiple paternity. One-quarter of males sired more than one clutch, although multiple mating by males is likely underestimated. The rate of multiple paternity in C. decresii represents one of the lowest among squamates and may be a result of successful male territoriality. However, the observed low rate of multiple paternity does not eliminate the possibility of widespread female multiple mating due to the potential for sperm storage and sperm competition. We conclude that the tawny dragon lizard employs a predomina...
Philosophical Transactions of the Royal Society B: Biological Sciences, 2017
Research on animal coloration is a vibrant area of biology currently involving evolutionary biolo... more Research on animal coloration is a vibrant area of biology currently involving evolutionary biologists, behavioural ecologists, psychologists, optical physicists, visual ecologists, geneticists and anthropologists. The proliferation of recent work requires that we take stock of the field, aiming to identify major themes, questions and future directions. This was the goal of the year-long Wissenschaftskolleg zu Berlin 'focus group' (2015-2016), in which many of
Philosophical Transactions of the Royal Society B: Biological Sciences, 2017
While basic research on animal coloration is the theme of this special edition, here we highlight... more While basic research on animal coloration is the theme of this special edition, here we highlight its applied significance for industry, innovation and society. Both the nanophotonic structures producing stunning optical effects and the colour perception mechanisms in animals are extremely diverse, having been honed over millions of years of evolution for many different purposes. Consequently, there is a wealth of opportunity for biomimetic and bioinspired applications of animal coloration research, spanning colour production, perception and function. Fundamental research on the production and perception of animal coloration is contributing to breakthroughs in the design of new materials (cosmetics, textiles, paints, optical coatings, security labels) and new technologies (cameras, sensors, optical devices, robots, biomedical implants). In addition, discoveries about the function of animal colour are influencing sport, fashion, the military and conservation. Understanding and applyi...
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Papers by Devi Stuart-fox