Conspicuous Coloration Research Articles

Latitudinal variation in sexual dimorphism in a freshwater fish group

AbstractTropical animals are characterized by showy ornaments and conspicuous body colours as compared with their temperate relatives. Some recent studies have hypothesized that sexual selection pressures are stronger in the tropics than in the temperate zone. Although negative correlations between latitude and the degree of sexual dimorphism would support this hypothesis, phylogeny should be taken into account in such comparative studies. Comparisons of the degree of sexual dimorphism in body size and fin lengths among species of the Adrianichthyidae, a freshwater fish family having a wide geographical range throughout Southeast and East Asia, revealed that lower latitude species are sexually more dimorphic in all characters than higher latitude species. Phylogenetic generalized least squares analyses using a mitochondrial DNA phylogeny demonstrated that the negative correlations between latitude and the degree of sexual dimorphism become non-significant when phylogeny is considered, but that the variance in the degree of sexual dimorphism is explained not only by phylogeny but also almost equally by latitude. Ancestral state reconstruction indicated that sexual dimorphisms have evolved independently even within major clades. These findings are consistent with the view that tropical species are exposed to stronger sexual selection pressures than temperate species. We discuss possible causes of the latitudinal variation in sexual selection pressure.

Intrasexual variability of a conspicuous social signal influences attack rate of lizard models in an experimental test

Colorful sexual traits are shaped by the opposing pressures of natural and sexual selection. Although increased conspicuousness improves mating success, an individual bearing brighter sexual traits may pay direct costs in terms of detectability to predators. While it is well established that the mere presence of non-aposematic, conspicuous sexual traits influences predation risk, little empirical work has examined how within-sex variability in sexual trait coloration affects attack rates; of these studies, results are equivocal. We experimentally tested the hypothesis that, within a single sex, brighter sexually selected traits impose a greater survival risk. We created clay models resembling male water anoles (Anolis aquaticus) and manipulated the coloration (bright red vs. brown-orange) of their colorful sexual ornament, the dewlap. Models were placed and monitored within A. aquaticus habitat. Our results suggest that a more conspicuous dewlap coloration is a cause of increased attack: redder models were attacked more than twice as often as less red models. Although previous studies have found correlational relationships between conspicuous coloration and predation, or have demonstrated long-term evolutionary changes in sexual dichromatism caused by a change in predator regime, our results show direct, within-lifetime costs of conspicuous sexual coloration among individuals of the same sex. These findings correspond well with a contemporary understanding of the drivers of female choice for costly male traits. These results also suggest the need for additional study on the effects of predation on the evolution of intrasexual variation in colorful sexual traits.

Up-regulation of phenylpropanoid biosynthesis system in peach species by peach aphids produces anthocyanins that protect the aphids against UVB and UVC radiation.

Conspicuous color is a common trait of foliar galls, but their relationship with gall-inducing insects is unknown. Red and green galls were taken from sunny or shady parts of peach species Prunus persica (L.) Batsch. f. rubro-plena Schneid with peach aphid Tuberocephalus momonis (Matsumura) infestation. We found that the loss of photosynthetic pigments was associated with the conspicuous coloration of green gall tissues. The concentrations of anthocyanins significantly increased following ultraviolet (UV) irradiation of green gall tissues, suggesting that accumulation of anthocyanins in red galls is related to ultraviolet B and C (UVB and UVC) radiation. The expression of structural genes related to the biosynthesis of chlorogenic acid and malic acid benzoate was increased in all gall tissues and negatively correlated with the expression profiles of certain genes associated with photosynthetic biosynthesis, indicating that the increased transcript levels of the phenylpropanoid pathway might cause loss of photosynthetic efficiency in the gall tissues. Transcriptome and quantitative reverse transcription PCR analyses revealed that MYB transcription factors that up-regulate the biosynthesis of anthocyanins in red gall tissues might be activated by both UVB and UVC exposure. Comet assays suggest that green and red gall tissues have similar DNA damage following UV irradiation. No obvious effect of the up-regulated compounds on the growth of the peach aphid was observed. Interestingly, peach aphids under leaves painted with anthocyanins had lower mortality following UV irradiation than those in controls. These results suggest that the anthocyanins in red gall tissues have a defensive function for the peach aphid, protecting it against UV radiation.

Conspicuous colours in a polymorphic orb-web spider: evidence of predator avoidance but not prey attraction

Conspicuous colours in animals are usually explained by mate attraction, predator avoidance and prey attraction. Predators may lure prey by mimicking food or other resources. Alternatively, some animals avoid predation by visually signalling unpalatability to predators. The evolution of a signal is affected by receiver processing mechanisms. Therefore, variation in sensory systems may explain the evolution of colour polymorphism of conspicuous species. We aimed to investigate the role of receivers in the evolution and maintenance of colour conspicuousness and polymorphism in Gasteracantha cancriformis (Araneidae). We tested two hypotheses: (1) conspicuous coloration is a prey lure strategy; (2) conspicuous coloration is a warning signal to predators. Furthermore, we identified the taxonomic order of prey captured and the type of predator (avian versus arthropod). To assess the role of prey, we conducted a field experiment in which webs were assigned to one of four treatments: yellow, red or black spider models, or no model. For each treatment, we counted the number of prey trapped on the webs and calculated the damaged area of the webs. To assess the role of predators, we conducted a second field experiment in which we attached yellow, red and black models to trees using nylon thread and observed the number of attack markings on each model. Our results did not corroborate the prey attraction hypothesis. In the predation experiment, black models had more attack markings, indicating that yellow and red models were less preferred. This suggests that spider coloration may play a role in predator avoidance. Colour polymorphism in this species is possibly a multifunctional attribute, where some morphs benefit from aposematism, whereas others may have alternative fitness advantages. Nonadaptive explanations should also be considered in future experiments of the evolution and maintenance of colour polymorphisms.

Combined Model Color-Correction Method Utilizing External Low-Frequency Reference Signals for Large-Scale Optical Satellite Image Mosaics

Optical satellites are affected by factors such as seasonal and atmospheric variation, illumination, and sensor distortion. Thus, satellite images covering large-scale area often show conspicuous color differences, resulting in poor color continuity of the mosaicked satellite image. This study proposes a novel combined model color correction (CMCC) method for high-resolution optical satellite images, which constructively combines a defogging model with a radiation correction model. First, this study analyzed the feasibility of using easily available low-resolution satellite images as external references to correct the color of high-resolution images and describes the selection criteria for external references. Second, considering the negative effects of atmosphere on the color and clarity of remote sensing images, we proposed an optical satellite image enhancement method, which is based on the content characteristics of remote sensing images and the dark channel prior defogging method. Finally, we designed a two-stage color correction process: 1) correcting the color of downsampled images via low-frequency modeling and replacement and 2) mapping the color of downsampled images to original images through local modeling and super-resolution color correction. Furthermore, this study proposes an indicator of quality considered mean absolute error (QCMAE) for quantitative evaluation of the color correction result. We selected 328 Gaofen-1 (GF-1) high-resolution images for the experiments. Visual effects and statistical results of images after being processed by the proposed CMCC are both superior to the three state-of-the-art methods, which verifies the effectiveness and reliability of the proposed method.

First report of a rare bloom of Ornithocercus magnificus, Stein 1883 along the coastal waters of Kochi; A possible indicator of increasing sea surface temperature

A bloom of the planktonic dinoflagellate, Ornithocercus magnificus was reported for the first time in the surface waters of the off Kochi coastal region with an evidently higher density of 1.7 x 106 cells L-1 on 18.12.2019. No conspicuous colouration of the surface waters was noticed even with the higher abundance of (1.7 x 106 cells L-1) observed near the barmouth area (6-7 m). The tracking on the occurrence of this genus in this region from 2013 to 2019 revealed their occurrence only during three times over the six years, i.e. the post monsoon season of 2013 and 2014 and during pre-monsoon of 2016. The SST of the three stations of the post monsoon season was compared for the last three years from 2017 to 2019, and an evident variation in the SST distribution was noticed in this region. The SST in 2019 was 2.1°C higher than that observed during 2017. The occurrence of Ornithocercus magnificus showed a positive correlation with SST (rs =0.425, p<0.05). It was also noted that the occurrence of this species was observed during the El Nino years. The Oceanic Nino Index (ONI) also positively correlated with the SST during the period (rs =0.432, p<0.05). The higher abundance of this species in 2019 when warmer SST was observed and their positive correlation with SST indicates the preferences of O.magnificus to warmer waters. The Shannon and Weiner diversity index (H’) ranged from 2.87-3.29 and the water quality index (WQI) remained good during the bloom. As Ornithocercus magnificus did occur during higher SST, this genus can be used as a proxy of climate change and hence has a strong potential to be used as indicator species of higher SST variation if found in novel environments.

The truth is in the detail: predators attack aposematic prey with less aggression than other prey types

AbstractAposematic organisms are often unprofitable to predators (e.g. because of defensive chemicals) which they advertise with a conspicuous signal (e.g. bright and conspicuous colour signals). Aposematism is thought to reduce predation of prey because the colour signal increases the ability of predators to learn, recognize and remember the prey’s defensive properties. The efficacy of aposematism has been extensively documented in laboratory studies, although its benefits seem to be harder to demonstrate in the field. In this study, we compared the levels of partial and overall predation among four prey types (undefended and cryptic, undefended and warning coloured, defended and cryptic, and aposematic prey). Overall, predation of warning coloured and defended (aposematic) prey was lower than the predation for cryptic and undefended prey; however, it was the same as predation of cryptic and defended prey. Moreover, aposematic prey had higher levels of partial predation (where prey was not wholly consumed by the predator) and lower attack intensities. This suggests that prey were being taste sampled, but also might be better able to survive attacks. Therefore, the benefits of aposematism may lie not only in reducing outright predation, but also in altering a predator’s post-attack behaviour, thus leading to greater escape opportunities and post-attack survival of prey. These results reinforce the importance of examining predation in more detail rather than simply examining attack rates.

Potential role of sensory bias in plumage pattern evolution: termite-eating and polka-dots in estrildid finches

Conspicuous colour patterns of animals, such as dots or stripes, can function as sexual and/or social signals. Their evolution is often explained by honest indicator mechanisms or the sensory exploitation hypothesis. In birds, however, the latter scenario has been scarcely tested. According to the sensory exploitation hypothesis, prey-like colour patterns can evolve when they contribute to attracting opposite-sex conspecifics by hitchhiking pre-existing sensory systems (sensory bias) that help foraging. Even without cheating scenarios, visual systems can serve as an underlying factor that facilitates the evolution of both foraging behaviours and colour patterns on the body. To test this idea, we examined the relationship between bird plumage patterns and diet using phylogenetic comparative approaches. Specifically, we focused on white polka-dot plumage patterns in estrildid finches and tested whether such patterns evolved for visual sensory systems that help foraging termites and other gregarious whitish small round prey items. Although we predicted that white polka-dots exist in termite-eater species, and that termite-eating evolved before the white polka-dot pattern, ancestral reconstruction did not reveal clear ancestral states for termite-eating. However, the phylogenetic regression model showed that species with conspicuous white polka-dots tended to be termite-eaters. We also found that estrildids with white polka-dots were likely to become termite-eaters, while those without white polka-dots were likely to become non-termite eaters, according to evolutionary transition analysis. These results are in contrast to the prediction of sensory exploitation hypothesis, wherein diet is believed to trigger the evolution of plumage patterns. However, the results presented here suggest that pre-existing sensory bias for white dots may have promoted the evolution of both termite-eating and white polka-dot plumage patterns in estrildids.

Analysis of Rhodamine B in Tomato Sauce Circulating at the Campus Canteen of Halu Oleo University, Kendari

Background:&#x0D; Food coloring is a food additive in the form of natural dyes and synthetic dyes when applied to food, able to give or improve color. rhodamine B is a synthetic dye that is very dangerous when inhaled, exposed to eyes or skin, and is swallowed. Of the 34 canteens at Halu Oleo University, all use tomato sauce and some are suspected of containing rhodamine B with bright and more conspicuous color characteristics.&#x0D; Objectives:&#x0D; This study aimed to analyze synthetic dye of rhodamine B in tomato sauce circulating at the canteen of Halu Oleo University, Kendari.&#x0D; Research Metodes: &#x0D; The type of study was descriptive. The population in this study was all types of tomato sauce used in 34 canteens of the Halu Oleo University, and the samples were 13 canteens obtained using the purposive sampling technique. Measurement of rhodamine B using test kits of rhodamine B.&#x0D; Results: &#x0D; The results showed that from 13 types of tomato sauce samples tested with test kits of rhodamine B by adding reagent (SbCl5 and Methyl Benzene) found 12 samples that did not change color (clear) means it did not contain rhodamine B (negative). But there was 1 sample of tomato sauce that changes color (purple), it means the tomato sauce was positive containing rhodamine B. The spectrophotometric test results obtained the amount of rhodamine B contained in the sample as many as 30.46842 ppm.&#x0D; Conclusion: &#x0D; Of the 13 canteens sampled, there was 1 canteen that used tomato sauce containing rhodamine B.&#x0D; Keywords: Rhodamine B, tomato sauce, canteen

Leaf-footed bugs possess multiple hidden contrasting color signals, but only one is associated with increased body size.

Antipredatory displays that incorporate hidden contrasting coloration are found in a variety of different animals. These displays are seen in organisms that have drab coloration at rest, but when disturbed reveal conspicuous coloration. Examples include the bright abdomens of mountain katydids and the colorful underwings of hawk moths. Such hidden displays can function as secondary defenses, enabling evasion of a pursuant predator. To begin to understand why some species have these displays while others do not, we conducted phylogenetic comparative analyses to investigate factors associated with the evolution of hidden contrasting coloration in leaf‐footed bugs. First, we investigated whether hidden contrasting coloration was associated with body size because these displays are considered to be more effective in larger organisms. We then investigated whether hidden contrasting coloration was associated with an alternative antipredatory defense, in this case rapid autotomy. We found that leaf‐footed bugs with hidden contrasting coloration tended to autotomize more slowly, but this result was not statistically significant. We also found that the presence of a body size association was dependent upon the form of the hidden color display. Leaf‐footed bugs that reveal red/orange coloration were the same size, on average, as species without a hidden color display. However, species that reveal white patches on a black background were significantly larger than species without a hidden color display. These results highlight the diversity of forms that hidden contrasting color signal can take, upon which selection may act differently.

Pectenovarin, A New Ovarian Carotenoprotein from Japanese Scallop Mizuhopecten yessoensis.

The scallop Mizuhopecten yessoensis accumulates carotenoids in the ovary during the maturation stage. Its conspicuous pink color implies the presence of carotenoprotein. However, the carotenoprotein from the scallop ovary has never been isolated and characterized, probably due to its instability and complexity. Here, we developed an extraction and isolation procedure for the carotenoprotein by employing a basic buffer containing potassium bromide to facilitate its efficient extraction from the ovary, and we succeeded in obtaining the carotenoprotein, termed pectenovarin. The carotenoid composition of the pectenovarin was similar to that of the ovary. The N-terminal and internal amino acid sequences of pectenovarin showed a high similarity to those of vitellogenin, the precursor of egg yolk protein under analysis.

Female prereproductive coloration reduces mating harassment in damselflies.

Conspicuous female coloration can evolve through male mate choice or via female-female competition thereby increasing female mating success. However, when mating is not beneficial, such as in pre-reproductive females, selection should favor cryptic rather than conspicuous coloration to avoid male detection and the associated harassment. Nevertheless, conspicuous female coloration occurs in many prereproductive animals, and its evolution remains an enigma. Here, I studied conspicuous female coloration in Agriocnemis femina damselflies, in which the conspicuous red color of the immature females changes to a less conspicuous green approximately a week after their emergence. I measured body size, weight, and egg numbers of the female morphs and found that red females are smaller and lighter and do not carry developed eggs. Finally, I calculated the occurrence frequency and mating frequency of red and green females in several populations over a three-year period. The results demonstrate that red females mated less frequently than green females even when red females were the abundant morph in the populations. I concluded that conspicuous female coloration is likely to function as a warning signal of sexual unprofitability, thereby reducing sexual harassment for females and unprofitable mating for males.

Predators as drivers of insect defenses

AbstractInsects have evolved various types of antipredator defenses. For example, many insects have evolved crypsis, and exhibit cryptic body colors and shapes for hiding from predators. Other insects produce toxins as a form of chemical defense against predators, and some toxic insects are aposematic, with conspicuous body colors for advertising their toxins. Insects can also develop hairs, spines or hard exoskeletons as morphological defenses to protect themselves from predation. In addition, insects can evolve behavioral defenses, in which insects exhibit autotomy or dropping, or feign death. This study investigated which predator types evoke these types of defenses, through a review of the effectiveness of antipredator defenses in insects against carnivorous animals that are commonly used as model predators in studies. These predators include other insects, spiders, fish, frogs, lizards, birds and mammals. The results provide the first step for clarifying the evolutionary drivers of antipredator defenses in insects. The following aspects should be considered for future studies: multiple predator species and sufficient replication, alternative prey and predator models, and tolerance to predators in insects.

A Matador-like Predator Diversion Strategy Driven by Conspicuous Coloration in Guppies

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 remain a multitude of species that display conspicuous coloration that cannot be explained by existing theory. Here we detail a new "matador-like" divertive antipredator strategy based on conspicuous coloration in Trinidadian guppies (Poecilia reticulata). Guppies encountering predatory fish rapidly enhance the conspicuousness of their eyes by blackening their irises. By pitting biomimetic robotic guppies against real predatory fish, we show this conspicuous eye coloration diverts attacks away from the guppies' center of mass to their head. To determine the function of this seemingly counterintuitive behavior, we developed a method for simulating escape probabilities when live prey interact with ballistic attacking predators, and find this diversion effect significantly benefits black-eyed guppies because they evade capture by rapidly pivoting away from the predator once it has committed to its attack. Remarkably, this antipredator strategy reverses the commonly observed negative scaling relationship between prey size and evasive ability, with larger fish benefiting most from diverting predators. Taken together, our results introduce a new antipredator divertive strategy that may be widely used by conspicuously colored prey that rely on agility to escape their predators.

Male ultraviolet reflectance and female mating history influence female mate choice and male mating success in a polyandrous lizard

AbstractPre-copulatory female mate choice based on male ultraviolet (UV) coloration has been demonstrated in several vertebrate species; however, post-copulatory mechanisms have been largely overlooked. Here, we investigated female mate preference based on male UV coloration in the common lizard Zootoca vivipara, in which males display conspicuous UV coloration on their throat. During two successive years, we staged sequential mating trials between females and four different males with UV-reduced or control belly and throat coloration. We recorded pre-copulatory female behaviour, copulation behaviour and assigned paternity to all offspring. Females were more aggressive towards UV-reduced males and, during the second year, UV-reduced males had a lower probability of siring at least one egg (fertilization success) during the last mating trials. However, in the second year, copulation was shorter with control males. Altogether, our results suggest that females exert subtle pre-copulatory mate preference based on male UV ornaments and, conditional on the study year and female mating history, some degree of post-copulatory preference for UV-control males leading to differential male fertilization success. This study suggests that UV-based female mate choice may be more widespread than previously thought in vertebrates, and emphasizes the importance of using a study design well adapted to the species reproductive behaviour.

Plastic sexual ornaments: Assessing temperature effects on color metrics in a color-changing reptile.

Conspicuous coloration is an important subject in social communication and animal behavior, and it can provide valuable insight into the role of visual signals in social selection. However, animal coloration can be plastic and affected by abiotic factors such as temperature, making its quantification problematic. In such cases, careful consideration is required so that metric choices are consistent across environments and least sensitive to abiotic factors. A detailed assessment of plastic trait in response to environmental conditions could help identify more robust methods for quantifying color. Temperature affects sexual ornamentation of eastern fence lizards, Sceloporus undulatus, with ventral coloration shifting from green to blue hues as temperatures rise, making the calculation of saturation (color purity) difficult under conditions where temperatures vary. We aimed to characterize how abiotic factors influence phenotypic expression and to identify a metric for quantifying animal color that is either independent from temperature (ideally) or best conserves individual's ranks. We compared the rates of change in saturation across two temperature treatments using seven metrics: three that are based on fixed spectral ranges (with two of them designed by us specifically for this system) and three that track the expressed hue (with one of them designed by us to circumvent spurious results in unornamented individuals). We also applied a lizard visual sensitivity model to understand how temperature-induced color changes may be perceived by conspecifics. We show that the rate of change in saturation between two temperatures is inconsistent across individuals, increasing at a higher rate in individuals with higher baseline saturation at lower temperatures. In addition, the relative color rank of individuals in a population varies with the temperature standardized by the investigator, but more so for some metrics than others. While we were unable to completely eliminate the effect of temperature, current tools for quantifying color allowed us to use spectral data to estimate saturation in a variety of ways and to largely preserve saturation ranks of individuals across temperatures while avoiding erroneous color scores. We describe our approaches and suggest best-practices for quantifying and interpreting color, particularly in cases where color changes in response to environmental factors.

Cassowary gloss and a novel form of structural color in birds.

One of the two lineages of extant birds resulting from its deepest split, Palaeognathae, has been reported not to exhibit structural coloration in feathers, affecting inferences of ancestral coloration mechanisms in extant birds. Structural coloration in facial skin and eggshells has been shown in this lineage, but has not been reported in feathers. We present the first evidence for two distinct mechanisms of structural color in palaeognath feathers. One extinct volant clade, Lithornithidae, shows evidence of elongate melanin-containing organelles uniquely associated with glossy/iridescent color, a structural color mechanism found in fossil outgroups and neognath birds. We also demonstrate a structural basis for the exceptional gloss in extant cassowary feathers. We propose gloss as an intermediate phenotype between matte and iridescent plumage, conferred by a thick and smooth feather rachis. Rachis-based structural color has not been previously investigated. The new data illuminate the relationships between avian melanin-based coloration and feather structure.

Spider lures exploit insect preferences for floral colour and symmetry

Sensory systems can capture only a fraction of available information, which creates opportunities for deceptive signalling. The sensory traps and sensory bias models have proven valuable for explaining how visual systems and environments shape the design of sexual signals, but their application to deceptive signals is largely limited to the context of pollination. Here we use the ‘jewelled’ orb-web spider Gasteracantha fornicata to experimentally test two longstanding hypotheses for the function of deceptive visual lures. Namely, that they: (1) exploit generalised preferences for conspicuous colouration (sensory bias), or (2) co-opt the otherwise-adaptive foraging response of prey toward flowers (sensory traps). In a field-based study we manipulated the conspicuous dorsal signals of female spiders along two axes—colour pattern and symmetry—to generate a gradient of floral resemblance and monitored the per-individual consequences for prey interception. As predicted by the sensory traps model, the most attractive phenotypes were those with flower-like radial symmetry and solid colour patterns, and their attractiveness equaled that of natural spiders. Taken with recent work demonstrating a close resemblance between G. fornicata and sympatric floral ‘models’, and pollinating insects as primary prey items, our results suggest that the deceptive colour-based lures of spiders function as inter-kingdom sensory traps via floral mimicry, and support the broader extension of sensory-based models to deceptive signalling contexts.

About the Cover

Previous articleNext article FreeAbout the CoverPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreCoverThe cover features the Hawaiian endemic shrimp, Halocaridina rubra, known by native Hawaiians as ‘ōpae ‘ula (literally, tiny red shrimp). These shrimp live in anchialine pools, which are small, shallow surface bodies of water with extensive subterranean connections to the sea and underground aquifers that can experience widely fluctuating gradients in temperature, salinity, and light. True to their Hawaiian name, they reach a maximum length of around one centimeter and typically display a red coloration with substantial variation. Halocaridina rubra is distributed across the islands of Oahu, Maui, and Hawaii, and at least eight unique genetic lineages have been identified. In the cover photo, each shrimp represents a different genetic lineage and displays the “typical” coloration observed for that lineage, highlighting the variation.In this issue (pp. 119–130), R. J. Weaver, B. K. Gonzalez, S. R. Santos, and J. C. Havird identify and quantify the pigment responsible for red coloration in H. rubra. Using chromatography and spectrophotometry, they found that the red carotenoid, astaxanthin, was more abundant in lineages that appeared redder than in lineages that were less colorful. Carotenoid supplementation experiments revealed that less colorful lineages were not limited by dietary access to pigments, suggesting a possible genetic basis for red coloration. By using a bioinformatic approach to explore the genetic basis for production of astaxanthin, they found that the gene responsible for astaxanthin production in H. rubra and other crustaceans is more closely related to a carotenoid metabolism gene found in fungi than to an astaxanthin gene found in birds and turtles. Despite the prevalence of red carotenoid coloration in animals, the genetic basis for this phenotype has only recently been explored and then mostly in vertebrate animals. Identifying the genetic basis for carotenoid coloration in non-vertebrate animals may prove useful in understanding the selective forces that drive the evolution of conspicuous coloration in this group.Credits: Photo, Ryan J. Weaver, University of Texas at Austin. Cover design, Jeannie Harrell, University of Chicago Press, and Ryan J. Weaver. Previous articleNext article DetailsFiguresReferencesCited by The Biological Bulletin Volume 238, Number 2April 2020 Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.1086/709957 © 2020 by The University of Chicago. All rights reserved.PDF download Crossref reports no articles citing this article.

Flash behavior in mammals?

Conspicuous coloration in animals has many possible functions including signaling to conspecifics, or predator deterrence through confusion, intimidation, and duping; the last includes flash behavior where predators are deceived into looking for conspicuous cues exhibited in flight but that are hidden when the animal comes to rest. In an effort to see if flash behavior occurs in mammals, we made predictions about situations where conspicuous coloration (as based on human assessment) might occur in artiodactyls and lagomorphs, and other predictions as to where such coloration might be found under an intraspecific signaling hypothesis. Using phylogenetically controlled analyses, we found that across species of artiodactyls, conspicuous rumps are more likely to have evolved in larger-sized group-living species supporting an intraspecific signaling function; this was not replicated in lagomorphs. Examining those artiodactyls that can facultatively expose color patches (putative flash behavior), we discovered that this trait occurred in artiodactyls that are solitary or living in very small groups irrespective of their body size. It is therefore possible that species such as white- and black-tailed deer, which display white rumps and tails during pursuit but hide them when stationary, are using flash behavior to confuse the predator into looking for the wrong object and thereby avoid detection and suggests that this form of antipredator defense in mammals needs greater attention. We found no effects of group size or body mass on conspicuous tail or ear markings in these taxa. Many mammals have conspicuous markings on their appendages and hindquarters, the function of which is mostly unknown. We matched these markings in rabbits, hares, and pikas and in bovids and cervids to both body size and group size across species. We found that conspicuous rumps are found in group living ungulates but when we separated these into conspicuous hindquarters always on display or that could be hidden, we found that hidden markings were principally found in species living alone or in very small groups irrespective of their body size. These species may expose conspicuous patches during flight but hide them at rest fooling the predator into searching for the wrong object, a relatively newly researched defense mechanism called flash behavior.