Animals benefit from phenotypic plasticity in changing environments, but this can come at a cost. Colour change, used for camouflage, communication, thermoregulation and UV protection, represents one ...of the most common plastic traits in nature and is categorised as morphological or physiological depending on the mechanism and speed of the change. Colour change has been assumed to carry physiological costs, but current knowledge has not advanced beyond this basic assumption. The costs of changing colour will shape the evolution of colour change in animals, yet no coherent research has been conducted in this area, leaving a gap in our understanding. Therefore, in this Review, we examine the direct and indirect evidence of the physiological cost of colour change from the cellular to the population level, in animals that utilise chromatophores in colour change. Our Review concludes that the physiological costs result from either one or a combination of the processes of (i) production, (ii) translocation and (iii) maintenance of pigments within the colour-containing cells (chromatophores). In addition, both types of colour change (morphological and physiological) pose costs as they require energy for hormone production and neural signalling. Moreover, our Review upholds the hypothesis that, if repetitively used, rapid colour change (i.e. seconds-minutes) is more costly than slow colour change (days-weeks) given that rapidly colour-changing animals show mitigations, such as avoiding colour change when possible. We discuss the potential implications of this cost on colour change, behaviour and evolution of colour-changing animals, generating testable hypotheses and emphasising the need for future work to address this gap.
Organisms capable of rapid physiological colour change have become model taxa in the study of camouflage because they are able to respond dynamically to the changes in their visual environment. Here, ...we briefly review the ways in which studies of colour changing organisms have contributed to our understanding of camouflage and highlight some unique opportunities they present. First, from a proximate perspective, comparison of visual cues triggering camouflage responses and the visual perception mechanisms involved can provide insight into general visual processing rules. Second, colour changing animals can potentially tailor their camouflage response not only to different backgrounds but also to multiple predators with different visual capabilities. We present new data showing that such facultative crypsis may be widespread in at least one group, the dwarf chameleons. From an ultimate perspective, we argue that colour changing organisms are ideally suited to experimental and comparative studies of evolutionary interactions between the three primary functions of animal colour patterns: camouflage; communication; and thermoregulation.
Reversible colour change in Arthropoda Umbers, Kate D. L.; Fabricant, Scott A.; Gawryszewski, Felipe M. ...
Biological reviews of the Cambridge Philosophical Society,
November 2014, Letnik:
89, Številka:
4
Journal Article
Recenzirano
ABSTRACT
The mechanisms and functions of reversible colour change in arthropods are highly diverse despite, or perhaps due to, the presence of an exoskeleton. Physiological colour changes, which have ...been recorded in 90 arthropod species, are rapid and are the result of changes in the positioning of microstructures or pigments, or in the refractive index of layers in the integument. By contrast, morphological colour changes, documented in 31 species, involve the anabolism or catabolism of components (e.g. pigments) directly related to the observable colour. In this review we highlight the diversity of mechanisms by which reversible colour change occurs and the evolutionary context and diversity of arthropod taxa in which it has been observed. Further, we discuss the functions of reversible colour change so far proposed, review the limited behavioural and ecological data, and argue that the field requires phylogenetically controlled approaches to understanding the evolution of reversible colour change. Finally, we encourage biologists to explore new model systems for colour change and to engage scientists from other disciplines; continued cross‐disciplinary collaboration is the most promising approach to this nexus of biology, physics, and chemistry.
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•Lotus root-compound pigment gel was prepared for 4D printing.•NaHCO3 was used as an external stimulus to induce color change in the printed gel.•Gels of 0.30 or 0.35 solid/liquid ...ratio had the best printing performance at 60 °C.•Spraying NaHCO3 solution to induce the rapid colour change was proved feasible.
The feasibility was investigated of 4D printing of lotus root gel compounded with a pigment that responds to pH change and alters colour. The pigment comprised of a combination of anthocyanins and lemon yellow; it was used in gel preparation for printing. The flowability and self-support properties of the lotus root-pigment gel were studied to evaluate its 3D printing performance. The gel viscosity decreased with the increase of printing temperature over the range 40, 50, and 60 °C. The gel with a ratio (lotus root powder/compound pigment) of 0.35 extruded smoothly and maintained high formability at temperatures below 60 °C. The pH response of compound pigment enabled the printed sample to change colour from reddish/yellowish to green after spraying with NaHCO3. The a* and b* values decreased significantly (p < 0.05) after spraying for 1 min. The gel with ratios of 0.30 and 0.35 achieved rapid colour change both superficially and internally. Through several different model designs (apple, Christmas tree, letters, and Chinese characters), high-quality 4D printing could be realized without problem. Thus, lotus root gel can be mixed with suitable pigments in correct proportion for 4D printing at appropriate temperature to ensure good flowability.
Dietary carotenoids change the colour of Southern corroboree frogs Umbers, Kate D. L.; Silla, Aimee J.; Bailey, Joseph A. ...
Biological Journal of the Linnean Society/Biological journal of the Linnean Society,
October 2016, 2016-10-00, 20161001, Letnik:
119, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Animal coloration can be the result of many interconnected elements, including the production of colour‐producing molecules de novo, as well as the acquisition of pigments from the diet. When ...acquired through the diet, carotenoids (a common class of pigments) can influence yellow, orange, and red coloration and enhanced levels of carotenoids can result in brighter coloration and/or changes in hue or saturation. We tested the hypothesis that dietary carotenoid supplementation changes the striking black and yellow coloration of the southern corroboree frog (Pseudophryne corroboree, Amphibia: Anura). Our dietary treatment showed no measurable difference in colour or brightness for black patches in frogs. However, the reflectance of yellow patches of frogs raised on a diet rich in carotenoids was more saturated (higher chroma) and long‐wave shifted in hue (more orange) compared to that of frogs raised without carotenoids. Interestingly, frogs with carotenoid‐poor diets still developed their characteristic yellow and black coloration, suggesting that their yellow colour patches are a product of pteridines manufactured de novo.
Currently, composite resins are widely used as aesthetic restorative materials. The success of any aesthetic restoration depends on the stability of the material’s colour. Colour change in composite ...resin restorations is one of the most frequent reasons for their replacement. The aim of this study is to evaluate the change in colouration, using the CIE L*a*b* colour system, of nanohybrid and microhybrid composite resins when they are exposed to potential staining solutions over a period of 14 days.
The aim of the paper was to find a direct connection between dynamic colour changes, phase changes and chemical interactions in model three-component leuco dye based thermochromic systems. The model ...systems, containing crystal violet lactone as a colour former, bisphenol A as a developer and 1-tetradecanol as a co-solvent, were analysed by DSC and FTIR spectroscopy and the results were related to the characteristics of the dynamic colour change. The ternary thermochromic systems were also compared with binary mixtures of the co-solvent with the developer and colour former, respectively. The temperatures characterizing the dynamic colour change at decolouration limits were directly related to the solid–liquid transition on heating and liquid–solid transition on cooling, regardless the concentration of bisphenol A. In ternary thermochromic systems, an indistinctive phase transition at the temperatures below the solid–solid (crystal–rotator) transition was observed. The straight connection between the phase transitions and temperatures characterizing the dynamic colour change at colouration limits was not proved. The colour contrast of thermochromic systems was found to be directly related to the ratio of integrated intensity of lactone ring opened (solid) and lactone ring closed (liquid) carbonyl vibration characterized by infrared spectroscopy.
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•Research of leuco dye based three-component thermochromic composites.•Investigation of phase changes and chemical interactions.•A strong relation between colour contrast and ratio of integrated intensity of carbonyl vibration could be observed.•Temperatures characterising the colour change at decolouration limit are close to those of the solid–liquid transition.
Animals from a wide range of taxonomic groups are capable of colour change, of which camouflage is one of the main functions. A considerable amount of past work on this subject has investigated ...species capable of extremely rapid colour change (in seconds). However, relatively slow colour change (over hours, days, weeks and months), as well as changes arising via developmental plasticity are probably more common than rapid changes, yet less studied. We discuss three key areas of colour change and camouflage. First, we review the mechanisms underpinning colour change and developmental plasticity for camouflage, including cellular processes, visual feedback, hormonal control and dietary factors. Second, we discuss the adaptive value of colour change for camouflage, including the use of different camouflage types. Third, we discuss the evolutionary–ecological implications of colour change for concealment, including what it can tell us about intraspecific colour diversity, morph-specific strategies, and matching to different environments and microhabitats. Throughout, we discuss key unresolved questions and present directions for future work, and highlight how colour change facilitates camouflage among habitats and arises when animals are faced with environmental changes occurring over a range of spatial and temporal scales.
This article is part of the themed issue ‘Animal coloration: production, perception, function and application’.
Camouflage can be achieved by both morphological (e.g. colour, brightness and pattern change) and behavioural (e.g. substrate preference) means. Much of the research on behavioural background ...matching has been conducted on species with fixed coloration and body patterns, while less is known about the role background choice plays in species capable of rapid (within minutes or seconds) colour change. One candidate species is the rock goby, Gobius paganellus, a common rock pool fish capable of rapid changes in colour and brightness when placed on different backgrounds. However, their ability to match different backgrounds is not unbounded, with some colours and brightness being easier to match than others, thus raising the possibility that gobies may use behavioural background matching to make up for their limited ability to match certain backgrounds. We used digital image analysis and a model of predator vision to investigate the ability of rock gobies to match chromatic (beige and greenish-grey) and achromatic (varying brightness) backgrounds. We then conducted choice experiments to determine whether gobies exhibited a behavioural preference for the backgrounds they were best at matching. Gobies rapidly changed their colour and brightness when placed on the different backgrounds. However, the level of camouflage differed between backgrounds: fish were better at matching beige than greenish-grey, and darker than lighter backgrounds. When given the choice, gobies displayed a behavioural preference for the backgrounds they were best at matching. Our findings therefore show that rock gobies, and probably other animals, use a combination of morphological and behavioural means to achieve camouflage and in doing so mitigate limitations in either approach alone.
•Gobies rapidly change colour and luminance in response to their background.•Fish were better at matching the colour beige than greenish-grey.•Gobies are much better at matching dark backgrounds than brighter ones.•Gobies show a behavioural preference for the background they are best at matching.•A mixture of behaviour and colour change probably helps mitigate limitations in both.
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