Habitat light, colour variation, and ultraviolet reflectance in the Grand Cayman anole, Anolis conspersus
01 Jul 2001-Biological Journal of The Linnean Society (No longer published by Elsevier)-Vol. 73, Iss: 3, pp 299-320
TL;DR: Evidence is presented to show how geological, ecological, and physiological factors could have interacted to select for a short wavelength-reflective dewlap from a long wavelength- reflective precursor following the colonization of Grand Cayman from Jamaica by A. grahami between 2 and 3 Mya.
Abstract: Data from a diversity of sources are consistent with the hypothesis that the Grand Cayman anole, Anolis conspersus, is descended directly from Anolis grahami of Jamaica. Although the two species have remained morphologically similar, coloration in A. conspersus has changed considerably from that of its ancestor. The most dramatic difference is seen in dewlap colour, where A. conspersus has evolved a blue and highly UV-reflective dewlap from the ancestral orange-and-yellow colour state. In addition, variation in normal (non-metachrosis) dorsum coloration in A. grahami populations is limited to shades of green (olive, emerald, teal), whereas in A. conspersus dorsum coloration varies from green to blue and to brown. This increased colour variation occurs despite Grand Cayman being a small, relatively featureless island only 35 km in length. Results of this study suggest that ambient light differences associated with precipitation-related vegetation structure may have played an important role in the evolution of A. conspersus body colour variation. Evidence is presented to show how geological, ecological, and physiological factors could have interacted to select for a short wavelength-reflective dewlap from a long wavelength-reflective precursor following the colonization of Grand Cayman from Jamaica by A. grahami between 2 and 3 Mya.
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TL;DR: Urosaurus ornatus exhibited chemosensory behavior at rates similar to rates reported for this species and lower than those reported for other phrynosomatid lizards, suggesting a lower reliance on chemical cues in social interactions.
Abstract: Although many lizard species detect and respond to conspecific chemical cues, variation in this ability among populations of the same species from different habitat types is less well understood. We compared chemoreceptive behaviors and head-bobs in response to conspecific chemical cues by Ornate Tree Lizards (Urosaurus ornatus) between populations from an upland forested habitat and a lowland desert habitat. Under this experimental design, U. ornatus from different habitats performed chemoreceptive behaviors and head-bobs at similar rates. Rate of chemoreceptive behaviors and head-bobs in response to chemical cues deposited by same- and opposite-sex conspecifics was higher than that of cues deposited by the subject in their home tank, demonstrating that U. ornatus has the ability to detect cues from conspecifics. Head-bob rate was also higher in same- and opposite-sex tanks compared to home tanks, demonstrating that chemical cues alter the rate of a social display behavior. Urosaurus ornatus exh...
5 citations
TL;DR: It is shown that male Tyrrhenian wall lizards display ultraviolet-blue and black colour patches that correlate positively with some aspect of their quality such as body or head size, and visual modelling procedure suggests that these lizards are able to distinguish the colours of their body parts from each other.
Abstract: Colour signals are ubiquitous in nature but only recently have researchers recognised the potential of ultraviolet (UV)-reflecting colour patches to function as signals of quality. Lacertid lizards often display UV-blue patches on their flanks and black spots over their entire body, both of which are under sexual selection. They also have a cryptic dorsum and some species have a conspicuous, polymorphic ventral coloration. In this study, we use the Tyrrhenian wall lizard Podarcis tiliguerta to investigate the information content of the lateral UV-blue patches and black melanin spots of males by assessing the relationship between colour features and individual quality traits. In addition, we use a visual modelling procedure to examine whether the coloration of the different body parts and different colour morphs can be distinguished by a wall lizard visual system. We found that larger males had more numerous and larger UV-blue patches, with a higher UV chroma, UV-shifted hue, but a lower spectral intensity than smaller males. The extent of black on the throat, dorsum, and flanks also correlated with male body size and size-corrected head length but not with colour features of the UV-blue patches. These results suggest that the UV-blue and melanic colour patches may provide different, non-redundant information about male resource holding potential, and thus act as condition-dependent indicators of male quality. Finally, we found that the different body parts can be chromatically distinguished from each other, and that the UV-blue patches are the most conspicuous while the dorsum is the least conspicuous. Many animals use their coloration to convey information about their quality as rivals or mates. Yet, until recently researchers have not recognised the potential of ultraviolet colour patches to function as signals of quality. In this study, we first show that male Tyrrhenian wall lizards display ultraviolet-blue and black colour patches that correlate positively with some aspect of their quality such as body or head size. Furthermore, our visual modelling procedure suggests that these lizards are able to distinguish the colours of their body parts from each other, with dorsal colours being the least conspicuous and ultraviolet-blue coloration being the most conspicuous.
5 citations
TL;DR: Testing whether opsin protein expression differs between divergent lineages of the tawny dragon that differ in the presence/absence of an ultraviolet sexual signal shows that gene expression between lineages does not differ significantly, including the UV wavelength sensitive SWS1.
Abstract: The sensory drive hypothesis predicts the correlated evolution of signaling traits and sensory perception in differing environments. For visual signals, adaptive divergence in both color signals and visual sensitivities between populations may contribute to reproductive isolation and promote speciation, but this has rarely been tested or shown in terrestrial species. We tested whether opsin protein expression differs between divergent lineages of the tawny dragon (Ctenophorus decresii) that differ in the presence/absence of an ultraviolet sexual signal. We measured the expression of four retinal cone opsin genes (SWS1, SWS2, RH2, and LWS) using droplet digital PCR. We show that gene expression between lineages does not differ significantly, including the UV wavelength sensitive SWS1. We discuss these results in the context of mounting evidence that visual sensitivities are highly conserved in terrestrial systems. Multiple competing requirements may constrain divergence of visual sensitivities in response to sexual signals. Instead, signal contrast could be increased via alternative mechanisms, such as background selection. Our results contribute to a growing understanding of the roles of visual ecology, phylogeny, and behavior on visual system evolution in reptiles.
4 citations
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...…2011; Endler & Day, 2006; Endler & Thery, 1996; Gunderson, Fleishman, & Leal, 2018; Heindl & Winkler, 2003; Klomp, Stuart‐Fox, Das, & Ord, 2017; Leal & Fleishman, 2002; Macedonia, 2001; Marshall, Philpot, & Stevens, 2016; Nafus et al., 2015; Sicsú, Manica, Maia, & Macedo, 2013; Uy & Endler, 2004)....
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01 Jan 2013
TL;DR: In this article, the reflectance and radiance of color patches on the wings of 90 tropical butterfly species that belong to groups with documented toxicity that vary in their habitat preferences were analyzed to test this prediction.
Abstract: 1. Aposematic signals advertise prey distastefulness or metabolic unprofitability to potential predators and have evolved independently in many prey groups over the course of evolutionary history as a means of protection from predation. Most aposematic signals investigated to date exhibit highly chromatic patterning; however, relatives in these toxic groups with patterns of very low chroma have been largely overlooked. 2. We propose that bright displays with low chroma arose in toxic prey species because they were more effective at deterring predation than were their chromatic counterparts, especially when viewed in relatively low light environments such as forest understories. 3. We analyzed the reflectance and radiance of color patches on the wings of 90 tropical butterfly species that belong to groups with documented toxicity that vary in their habitat preferences to test this prediction: Warning signal chroma and perceived chromaticity are expected to be higher and brightness lower in species that fly in open environments when compared to those that fly in forested environments. 4. Analyses of the reflectance and radiance of warning color patches and predator visual modeling support this prediction. Moreover, phylogenetic tests, which correct for statistical non-independence due to phylogenetic relatedness of test
4 citations
Cites background from "Habitat light, colour variation, an..."
...(Macedonia 2001)....
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...Macedonia from Grand Caymen Island during the middle of the day? (Macedonia 2001)....
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...mammals and insects to attract mates or indicate status (Papke, Kemp & Rutowski 2007; Kemp 2008; McGraw, Dale & Mackillop 2003; Macedonia 2001)....
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...Bright plumage, integument, or other tissues are used by many animals including birds, 3 mammals and insects to attract mates or indicate status (Papke, Kemp & Rutowski 2007; Kemp 2008; McGraw, Dale & Mackillop 2003; Macedonia 2001)....
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Dissertation•
08 Oct 2013
3 citations
References
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TL;DR: Sensory systems, signals, signaling behavior, and habitat choice are evolutionarily coupled and should coevolve in predictable directions, determined by environmental biophysics, neurobiology, and the genetics of the suites of traits.
Abstract: There is a bewildering diversity of signals, sensory systems, and signaling behavior. A consideration of how these traits affect each other's evolution explains some of this diversity. Natural selection favors signals, receptors, and signaling behavior that maximize the received signals relative to background noise and minimize signal degradation. Properties of sensory systems bias the direction of evolution of the signals that they receive. For example, females may prefer males whose signals they can perceive more easily, and this will lead to the spread of more easily perceived male traits. Environmental conditions during signal transmission and detection also affect signal perception. Specific environmental conditions will bias the evolutionary direction of behavior, which affects the time and place of signaling as well as microhabitat preferences. Increased specialization of microhabitats and signaling behavior may lead to biased evolution of the sensory systems to work more efficiently. Thus, sensory...
1,717 citations
TL;DR: The first observation may be related to the first in the following way: nonsynchronous spatial overlap could dictate relatively great resource overlap for species coinhabiting patchy or edge areas, requiring great differences between the species in prey size in addition to those in climatic habitat.
Abstract: Sympatric native Anolis species with similar structural habitats but contrasting climatic habitats are closer in head and body size on species—rich than on depauperate islands. In two localities, sympatric Anolis species with differential occurrences in sun or shade sought lower, more shaded perches during midday, resulting in partly nonsynchronous utilization of the vegetation by the two species. The second observation may be related to the first in the following way: nonsynchronous spatial overlap could dictate relatively great resource overlap for species coinhabiting patchy or edge areas, requiring great differences between the species in prey size in addition to those in climatic habitat. The extent of such overlap on small depauperate islands could be greater if these contained a greater proportion of patchy or edge habitats (with respect to insolation), or if climatic preferences were broader and more overlapping than on large, species—rich islands. In each locality, the relatively more shade—inhab...
1,562 citations
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...Schoener TW. 1970....
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TL;DR: Until the authors know more about how and why natural selection occurs, attempts to measure it are quixotic, and discussions of its importance are theandric.
Abstract: All too often in evolutionary biology we are led to speculate or infer the mode of action of natural selection; we usually do not know why some individuals are more adaptive than others. Very often attempts to measure natural selection are unsuccessful, leading to heated arguments about' the relative importance of selection, genetic drift, and epistasis in evolution (Lewontin, 1974). Until we know more about how and why natural selection occurs, attempts to measure it are quixotic, and discussions of its importance are theandric. It is no coincidence that most of the successful studies of natural selection have dealt with animal color patterns; it should be obvious which color patterns are more adaptive in the presence of visually hunting predators. The adaptive significance of warning coloration and mimicry of distasteful species has been worked out (Cott, 1940; Wickler, 1968; Edmunds, 1974; Rothschild, 1975; Turner, 1977). But most species are neither distasteful nor mimetic; most have inconspicuous or cryptic color patterns in their natural habitats (Poulton, 1890; Thayer, 1909; Cott, 1940; Endler, 1978). Most field and experimental studies have shown that the overall color or tone of inconspicuous species matches or approximates the background (DiCesnola, 1904; Sumner, 1934, 1935; Isley, 1938; Popham, 1942; Dice, 1947; Kettlewell, 1956, 1973; Turner, 1961; Kaufman, 1974; Wicklund, 1975; Curio, 1976), but they treated species with solid colors or
1,290 citations
TL;DR: New methods make it practical to measure the colour spectrum of pattern elements (patches) of animals and their visual backgrounds for the conditions under which patch spectra reach the conspecific's, predator's or prey's eyes.
Abstract: In studies of animal colouration it is no longer necessary to rely on subjective assessments of colour and conspicuousness, nor on methods which rely upon human vision. This is important because animals vary greatly in colour vision and colour is context-dependent. New methods make it practical to measure the colour spectrum of pattern elements (patches) of animals and their visual backgrounds for the conditions under which patch spectra reach the conspecific's, predator's or prey's eyes. These methods can be used in both terrestrial and aquatic habitats. A patch's colour is dependent not only upon its reflectance spectrum, but also upon the ambient light spectrum, the transmission properties of air or water, and the veiling light spectrum. These factors change with time of day, weather, season and microhabitat, so colours must be measured under the conditions prevalent when colour patterns are normally used. Methods of measuring, classifying and comparing colours are presented, as well as techniques for assessing the conspicuousness of colour patterns as a whole. Some implications of the effect of environmental light and vision are also discussed.
1,140 citations
TL;DR: The structure of forests leads to four major light habitats when the sun is not blocked by clouds: forest shade, woodland shade, small gaps, and large gaps, respectively, characterized by yellow—green, blue—gray, reddish, and "white" ambient light spectra, respectively.
Abstract: Forests exhibit much variation in light environments, and this can affect communication among animals, communication between animals and plants, photosynthesis, and plant morphogenesis. Light environments are caused by, and can be predicted from, the geometry of the light paths, the weather conditions, and the time of day. The structure of forests leads to four major light habitats when the sun is not blocked by clouds: forest shade, woodland shade, small gaps, and large gaps. These are characterized by yellow—green, blue—gray, reddish, and "white" ambient light spectra, respectively. When the sun is blocked by clouds, the spectra of these four habitats converge on that of large gaps and open areas, so the single light environment during cloudy weather will be called open/cloudy. An additional light environment (early/late) is associated with low sun angles (near dawn or dusk); it is purplish. Each light environment is well defined and was found in forests of Trinidad, Panama, Costa Rica, Australia, California, and Florida. Scattered literature references suggest similar patterns elsewhere in North America, Europe, and Java. Perceived colors of animals, flowers, and fruits depend upon the interaction between ambient light color and the reflectance color of the animal or plant parts. As a result, an animal or plant may have a different appearance in each environment, i.e., a color pattern may be relatively cryptic in some light environments while relatively conspicuous in others. This has strong implications for the joint evolution of visual signals and vision, as well as microhabitat choice. Plant growth and form may also be affected by variation in the color of forest light.
1,108 citations
"Habitat light, colour variation, an..." refers background in this paper
...For visual signals, FOR ANIMAL COLOUR SIGNALS relevant ecological variables include the ambient light Endler (1992, 1993) has shown that, under sunnyspectrum in which a signal is viewed and features of skies, four types of structural light habitats occur inthe visual background from which the…...
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...…because their reflectance spectra will mented, anoles that inhabit dark forest environmentschange with changing light conditions, making them exhibit dewlaps that may be white or yellow, butharder to recognize and track (Endler, 1993). which are never orange or red (Fleishman, 1992)....
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...Legend as in Table 1. different forest light environments (e.g. Endler, 1992, 1993)....
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...…& Leal, 1993; Macedonia et al., 2000; Stoehr & McGraw, 2001).most reflective colour patch would be yellow-green because it most closely resembles the ambient spec- Traditionally, the function ascribed to dewlap colour has been one of species recognition and reproductivetrum (e.g. Endler, 1993)....
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