Female Coloration Research Articles

Annual molt period and seasonal color variation in the Eared Dove´s crown.

Molting is an important process in which old and worn feathers are exchanged for new ones. Plumage color is determined by pigments such as carotenes, melanin and by the ultrastructure of the feather. The importance of plumage coloration has been widely studied in different groups of birds, generally at a particular time of the year. However, plumage coloration is not static and few studies have addressed the change in plumage color over time and its relationship to reproductive tasks. The Eared Dove (Zenaida auriculata, Des Murs, 1847) has a melanistic coloration with sexual dichromatism in different body regions. The Eared Dove´s crown is the most exposed body region during the bowing display. Our objective was therefore to accurately determine the molting period of the crown feathers and study the seasonal variation in their coloration in females and males. Our findings indicate a molting period of 6 months (January to June). The new feathers are undergoing changes in their coloration from July to December. During that period we apply an avian vision model then enabled us to reveal a seasonal variation in the coloration of the crown feathers in both sexes, as given by a change in the chromatic distances. The highest values in the chromatic distances towards the reproductive period are given by a change in the UV-violet component of the spectrum, indicating changes in the microstructure of the feather. This change in crown coloration towards the breeding season could be linked to reproductive behaviors.

Keanekaragaman Morfologis Sukun [Artocarpus altilis (Park.) Fosberg. var. non-seminiferus] Di Daerah Banyumas

Breadfruit [Artocarpus altilis (Park.) Fosberg] is a plant that have different morphological variations in each region. The Banyumas area is an area that is very suitable for the growth of breadfruit. This study was aimed to determine the diversity of breadfruit plants based on their morphological characteristics. This research was conducted using a survey method, then the data were analyzed descriptively. The research variable was the morphological characteristics of the breadfruit plant, the parameters were the morphological of the canopy, buttress roots, stems, leaves, flowers, and fruits. The results showed that the morphological variations of breadfruit were found in the shape of the canopy varies, namely broad pyramid, pyramid, ovoid, round, and irregular, some have buttress roots and none, fruit shape varies, namely round and oval. Leaf blade length varies between 26-56 cm, leaf blade width varies between 20-45 cm, leaf stalk length varies between 3-6 cm, leaf shape is ovoid, upper leaf surface is smooth, lower leaf surface is rough, leaf edge incised, the tip of the leaf is tapered, the base of the leaf is wedged, the color of the leaf is dark green. Male flower length varies between 9-17 cm, male flower color varies, namely light green and brownish, male flower shape resembles a club, female flower diameter varies between 5-6 cm, female flower shape is round, female flower color is light green. Fruit weight varies between 450-1250 g, fruit diameter varies between 9-18 cm, fruit skin color is green, flesh color is white to yellowish white, flesh texture is smooth, fruit skin pattern is polygonal, and seeds are round, black.

중학생들의 학교 공간별 색채 선호도 분석

Objectives The purpose of this study is to analyze the color preference of middle school students by school space.
 Methods This study analyzed 275 middle school students' color preferences for school spaces such as classrooms, corridors, toilets, restaurants, auditoriums, and special rooms. χ2 of the SPSS program and frequency analysis were used as data processing methods. Frequency analysis is to understand color preference by school space, and cross-analysis is to understand whether there is a difference between male and female students in color preference.
 Results Middle school boys and girls preferred white color as the basic preferred color for most school spaces such as classrooms, corridors, toilets, cafeterias, math rooms, English rooms, art rooms, music rooms, libraries, auditoriums, and exterior walls. However, as a basic preferred color for the science room space, male students preferred blue color the most, but female students preferred white color the most.
 Conclusions White color is the basis for each school space, but efforts are required to apply another color that matches white color in harmony.

Fight, flight or bright(en)

When you think of colour-changing animals, what comes to mind? A slow-moving chameleon barely distinguishable from its spot in a tree? Or maybe an octopus camouflaging itself on the ocean floor? What about hundreds of bright yellow male Asian common toads (Duttaphrynus melanostictus) gathering to fight each other for the company of their somewhat drab, brown-coloured mates? During monsoon rains, the toads gather in groups of over 200 individuals at breeding sites throughout South and Southeast Asia. Before congregating, the male toads swiftly change colour to a conspicuous yellow, signalling to other males that they are ready to fight – and to distinguish themselves to potential female mates. Unsurprisingly, hormones associated with the ‘fight or flight’ response are high during these ‘explosive breeding’ events thanks to the stressful monsoon rains that coincide with the mating season and fighting for partners. Could these hormones have something to do with the toads’ striking colour change? Susanne Stückler and Doris Preininger from the University of Vienna, Austria, and their colleague Matthew Fuxjager from Brown University, USA, decided to investigate.The trio turned to a group of toads housed in Vienna Zoo, Austria, to see which hormones were responsible for the colour change. First, they measured the colour of the toads’ backs – specifically, the hue (what we normally think of when we describe colour), brightness (lightness or darkness) and chroma (colour saturation). Having established the toads’ baseline colour, the researchers tested whether a dose of the reproductive hormone human chorionic gonadotropin (hCG) could trick the toads into thinking that it was breeding season and trigger a rapid colour change. Surprisingly, the toads did not turn bright yellow when they experienced an increase in their reproductive hormone levels. If reproductive hormones such as hCG aren't triggering a change in colour, could the hormones associated with a stressful experience be driving the colourful transformation instead?To test this, the scientists gave the toads one of the stress hormones, either adrenaline (epinephrine) or noradrenaline (norepinephrine), and again recorded the toads’ hue, brightness and colour saturation. With either stress hormone, the toads became brighter and their shade of yellow became more saturated. Interestingly, for these toads, only a grape-sized patch of skin changed colour (about half the size of the body), and a few did not change colour at all.To make sure any colour changes the scientists saw in these treatments could actually be seen by potential mates (or sparring partners), Stückler and colleagues also calculated how noticeable the colour changes would be to the eyes of a toad. Using the colour perception data of a close relative, the common toad (Bufo bufo), the scientists were able to estimate just how different this stress-induced yellow would be from the typical brown colour of females or males – and indeed, the yellow stood out! The scientists suggest that to trigger the whole-body colour change, perhaps there are other hormones at play that they haven't tested yet. Or perhaps physical signals such as monsoon rains and social cues such as the company of other toads work together with stress hormones during explosive breeding events in the wild.This is the first time that stress hormones alone have been shown to cause animals to change colour rapidly without the help of other hormones that signal breeding. For Asian common toads, being a brighter, flashier yellow might make them more successful during these explosive breeding events, so it would make sense that they have embraced another means to quickly change colour. So, next time you think of colour-changing animals, perhaps you'll picture the bright yellow Asian common toad – and how their ‘fight or flight’ hormones have now been adopted for flashiness.

Evolution of female colours in birds: The role of female cost of reproduction and paternal care.

Female ornamentation is frequently observed in animal species and is sometimes found as more evolutionary labile than male ornamentation. A complex array of factors may explain its presence and variation. Here we assessed the role of female cost of reproduction and paternal care. Both factors have been pinpointed as important by theoretical studies but have not been investigated yet in details at the interspecific level. We worked on 133 species of North temperate Passeriformes bird species for which both the clutch volume - here taken as the proxy of female cost of reproduction - and amount of paternal care are relatively well known. Using spectrometry, we measured the whole-body coloured plumage patches and quantified three metrics corresponding to brightness (i.e. achromatic component), colour chromaticity (i.e. intensity) and colour volume (i.e. diversity). We found a strong association between male and female colour metrics. Controlling for this association, we found additional small but detectable effects of both cost of reproduction and paternal care. First, females of species with more paternal care were slightly brighter. Second, the interaction between the level of paternal care and egg volume was correlated with female colour intensity: females with more paternal care were more chromatic, with this association mostly present when their investment in reproduction was low. Together these results suggest that female cost of reproduction and paternal care are part of the multiple factors explaining variation of female coloration, besides the strong covariation between male and female coloration.

Does sexual conflict contribute to the evolution of novel warning patterns?

Why warning patterns are so diverse is an enduring evolutionary puzzle. Because predators associate particular patterns with unpleasant experiences, an individual's predation risk should decrease as the local density of its warning pattern increases, promoting pattern monomorphism. Distasteful Heliconius butterflies are known for their diversity of warning patterns. Here, we explore whether interlocus sexual conflict can contribute to their diversification. Male Heliconius use warning patterns as mating cues, but mated females may suffer costs if this leads to disturbance, favouring novel patterns. Using simulations, we show that under our model conditions drift alone is unlikely to cause pattern diversification, but that sexual conflict can assist such a process. We also find that genetic architecture influences the evolution of male preferences, which track changes in warning pattern due to sexual selection. When male attraction imposes costs on females, this affects the speed at which novel pattern alleles increase. In two experiments, females laid fewer eggs with males present. However, although males in one experiment showed less interest in females with manipulated patterns, we found no evidence that female colouration mitigates sex-specific costs. Overall, male attraction to conspecific warning patterns may impose an unrecognized cost on Heliconius females, but further work is required to determine this experimentally.

Female and male plumage brightness is positively correlated among populations of the dichromatic Variable Seedeater

Abstract Because studies of plumage coloration often focus on highly elaborate and conspicuous males, little is known about the factors driving theevolution of drab plumage in females of dichromatic species. We explored variation in the color properties of drab female plumage across subspecies of the Variable Seedeater (Sporophila corvina) and found a correlation between plumage brightness of male and female plumage patches. This correlation is consistent with the hypothesis that differences in plumage brightness among females result, at least partially, from a genetic correlation or shared developmental pathway with the more conspicuous male plumage traits that are shaped by sexual selection. Furthermore, we modeled the perception of female plumage using the avian visual system and found that most of the variation in color among females is undetectable by birds; therefore, it is unlikely for such variation to have evolved via direct sexual selection as a signal for recognition or assortative mating. Together, these results suggest that variation in S. corvina female color result from non-adaptive processes. However, we found a reduced variation on color of dorsal patches compared with that of ventral patches among females, which could be explained by natural selection on crypsis, reducing the variation on dorsal patches. Finally, we found little differences in plumage color between adult females and juveniles, which suggest selection for juveniles to resemble adult females possibly to reduce aggression from adult males. Additional within-population studies and behavioral experiments are needed to discern the evolutionary factors driving variation on S. corvina female color and its function.

Female condom color and scent preference in Durban, South Africa

ObjectivesTo assess preferences for female condom (FC) colors and scents. Study designWomen aged 18–40 years were randomized to one of three FCs (FC2, Cupid1, Cupid2) two of which offered a choice of color and scent (red/strawberry, purple/vanilla, natural/unscented). Women could choose any variety within condom types while participating in an FC contraceptive efficacy study in South Africa. ResultsOne hundred and thirty-three women were allocated to each FC type. Strawberry was the most popular variety for both FC2 and Cupid1 (60.9%, 78.3% respectively). Some women chose more than one variety but few chose the natural. ConclusionsData support a clear preference for colored and scented FCs. ImplicationsThese data can inform FC programme managers to predict demand for different varieties of FC and can adjust supply of FCs accordingly.

Effects of Aging on Hair Color, Melanosomes, and Melanin Composition in Japanese Males and Their Sex Differences.

In a previous study, we observed that the hair color of Japanese females darkens with age and that the causes of this are the increase in melanosome size, the amount of melanin, and the mol% of 5,6-dihydroxyindole (DHI) which has a high absorbance. In this study, we extended the same analyses to male hair to examine the sex differences in hair color, melanin composition, and melanosome morphology. Male hair also tended to darken with age, but it was darker than female hair in those of younger ages. Although there was no age dependence of DHI mol% in male hair, as with female hair, the melanosomes' sizes enlarged with age, the total melanin amount increased, and these findings were correlated with hair color. The analyses, considering age dependence, revealed that there were significant sex differences in the ratio of absorbance of dissolved melanin at the wavelength of 650 nm to 500 nm, in pheomelanin mol%, and in melanosome morphology parameters such as the minor axis. This may be the cause of the sex differences in hair color. Furthermore, the factors related to hair color were analyzed using all the data of the male and female hairs. The results suggested that total melanin amount, pheomelanin mol%, and DHI mol% correlated with hair color.

Oestradiol reduces female bill colour in a mutually ornamented bird.

Carotenoid-based colour signals can be costly to produce and maintain, and trade-offs between signalling and other fitness traits are expected. In mutually ornamented species, trade-offs with reproduction may be stronger for females than males, because females often dedicate more resources to offspring production, which may lead to plastic investment in colour signals and plastic sexual dichromatism. Oestradiol is a candidate mediator of this trade-off because it regulates reproductive physiology and may also influence the expression of coloration. We tested this hypothesis by giving female common waxbills (Estrilda astrild) either oestradiol (17β-oestradiol) or empty implants during the early breeding season and measured spectral reflectance of carotenoid-based bill coloration weekly for two months. Using a model of avian vision, we found that bill colour in oestradiol-implanted females became less saturated, less red in hue and brighter, compared with control females and with unimplanted males. This resulted in a change in bill sexual dichromatism from imperceptible to perceptible. Results support the hypothesis that female reproductive physiology influences investment in coloration through changes in oestradiol and show a form of female-driven plastic sexual dichromatism. Greater sensitivity of female colour to physiological and/or environmental conditions helps explain why differences in sexual dichromatism among species differing in ecology often evolve owing to changes in female rather than male phenotype.

Black and orange coloration predict success during male–male competition in the guppy

AbstractInvestigating how intrasexual competition and intersexual mate choice act within a system is crucial to understanding the maintenance and diversity of sexually-dimorphic traits. These two processes can act in concert by selecting for the same trait, or in opposition by selecting for different extremes of the same trait; they can also act on different traits, potentially increasing trait complexity. We asked whether male–male competition and female mate choice act on the same male traits using Trinidadian guppies, which exhibit sexual size dimorphism and male-limited color patterns consisting of different colors arranged along the body and fins. We used behavioral assays to assess the relationship between color and competitive success and then compared our results to the plethora of data on female choice and color in our study population. Males initiated more contests if they were larger than their competitor. Males won contests more often if they had more black coloration than their competitor, and the effect of black was stronger when males had less orange than their competitor. Additionally, males won more often if they had either more structural color (iridescence) and more orange, or less structural color and less orange than their competitor, suggesting multiple combinations of color traits predict success. Females from our study population exhibit a strong preference for more orange coloration. Thus, traits favored in male contests differ from those favored by intersexual selection in this population. These results suggest that inter- and intrasexual selection, when acting concurrently, can promote increased complexity of sexually selected traits.

Why Are Snowy Owls White and Why Have They Evolved Distinct Sexual Color Dimorphism? A Review of Questions and Hypotheses

Abstract Many Arctic animals are white throughout their life, or turn white seasonally, with no distinct sexual color dimorphism. Common knowledge assumes these animals are white for camouflage in snow-covered landscapes. Presumably, this camouflage adaptation provides concealment from predators, and conversely, concealment for predation. This adaptation appears to be independent of sex. These theories seem logical; however, natural selection could also favor white coloration for other reasons. The Snowy Owl (Bubo scandiacus) is unusual because in addition to being white, it also shows sexual color dimorphism. Both sexes exhibit delayed plumage maturation. As yearlings, males and females are heavily marked with brown bars and spots on a white-based plumage. Males and females are believed to become whiter as they age. Males become almost pure white, while females retain brown bars and spots. As adults, males and females are distinctly sexually dimorphic in coloration and plumage patterning. These traits are not consistent with most other species of white Arctic animals, or most other species of owls. Snowy Owls are thought to share a common ancestor with the genus Bubo, especially Great Horned Owls (Bubo virginianus) from North America. This separation took place approximately four million years ago. If true, the evolution of white-based plumage in Snowy Owls was probably the result of natural selection favoring camouflage color in snow-covered environments, as Snowy Owls evolved and expanded into Arctic habitat. However, natural selection in concert or compromise with sexual selection, likely drove the evolution of sexual color dimorphism, and delayed plumage maturation, as a result of a snow-free tundra, and 24 hr of daylight during the breeding season. Natural selection appears to have independently favored different male and female plumage coloration and patterning. I propose that adult females evolved white plumage, interrupted with brown bars and spots, predominately for camouflage. Likewise, I propose that adult males evolved white plumage for at least two social signaling strategies: (1) to advertise their relative age, social status, and genotypic quality to females, and (2) to advertise relative age and social status to other males.

Simple and complex, sexually dimorphic retinal mosaic of fritillary butterflies.

Butterflies have variable sets of spectral photoreceptors that underlie colour vision. The photoreceptor organization may be optimized for the detection of body coloration. Fritillaries (Argynnini) are nymphalid butterflies exhibiting varying degrees of sexual dimorphism in wing coloration. In two sister species, the females have orange (Argynnis paphia) and dark wings (Argynnis sagana), respectively, while the males of both species have orange wings with large patches of pheromone-producing androconia. In spite of the differences in female coloration, the eyes of both species exhibit an identical sexual dimorphism. The female eyeshine is uniform yellow, while the males have a complex retinal mosaic with yellow and red-reflecting ommatidia. We found the basic set of ultraviolet-, blue- and green-peaking photoreceptors in both sexes. Males additionally have three more photoreceptor classes, peaking in green, yellow and red, respectively. The latter is the basal R9, indirectly measured through hyperpolarizations in the green-peaking R1-2. In many nymphalid tribes, including the closely related Heliconiini, the retinal mosaic is complex in both sexes. We hypothesize that the simple mosaic of female Argynnini is a secondary reduction, possibly driven by the use of olfaction for intraspecific recognition, whereas vision remains the primary sense for the task in the males. This article is part of the theme issue 'Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods'.

Two billion registered students affected by stereotyped educational environments: an analysis of gender-based color bias

According to the literature, educational technologies present several learning benefits to promote online education. However, there are several associated challenges, and some studies illustrate the limitations in elaborating educational technologies, called Design limitations. This aspect is responsible for unleashing various issues in the learning process, such as gender inequality, creating adverse effects on cognitive, motivational, and behavioral mediators, which opposes the fifth UN’s Sustainable Development Goal. Therefore, many studies notice the harmful effects of stereotypes in educational technologies. These effects can be included in the design, like colors or other stereotyped elements, or how the activity is conducted. Based on this, the present study aimed to verify the predominance of color bias in educational technologies available on the WEB. This study developed a computational solution to calculate male and female color bias in the available educational technology web pages. The results suggest the prevalence of the development of educational technologies with a male color bias, with an imbalance among genders, without adequate customization for age groups. Furthermore, some environments, such as Computer Science, present a higher color bias for men when compared to women. Despite both scales being independent, results indicated interesting evidence of a substantial prevalence of colors associated with the male scale. According to the literature, this may be associated with dropout and lack of interest in female students, especially in sciences, technology, engineering, and mathematics domains.

What do male and female zebrafish prefer? Directional and colour preference in maze tasks.

Studies regarding the animals' innate preferences help elucidate and avoid probable sources of bias and serve as a reference to improve and develop new behavioural tasks. In zebrafish research, data obtained in behavioural assessments are often not replicated between research groups or even inside the same laboratory raising huge concerns about replicability and reproducibility. Among the potential causes that are not well considered, sexual differences can be a probable source of bias. Thus, this study aimed to investigate the male and female zebrafish directional and colour preferences in the plus-maze and T-maze behavioural tasks. Experiment 1 evaluated directional preference, and experiment 2 evaluated colour preference in a plus-maze task; experiment 3 evaluated preference between black or white in a T-maze task. Individual preferences were expressed as the percentage of time spent in each zone. Our results showed that male and female zebrafish demonstrated no difference in directional preference in the plus-maze task. Surprisingly, male and female zebrafish showed colour preference differences in the plus-maze task; males did not show any colour preference, while female zebrafish demonstrated a red preference compared to white, blue and yellow colours. Moreover, both male and female zebrafish demonstrated a strong black colour preference compared to the white colour in the T-maze task. Our findings characterized the spontaneous preference of male and female zebrafish for direction and colour, identifying possible biases and providing insights that contribute to the standardization of future protocols.

The conspicuousness contradiction: brighter males have lower mating chances in the damselfly Argia hasemani but not in Argia croceipennis

Abstract In odonates, male coloration is often more conspicuous than female coloration. This difference is frequently attributed to the role of male colour in male–male competition to access females. However, there are sexually dimorphic odonate species, such as the damselflies Argia hasemani and Argia croceipennis, in which male–male interactions are much less intense. In these species, it might be that male coloration affects male success directly when interacting with females. Therefore, we hypothesized that males with more intense coloration present higher copulation success. To investigate this hypothesis, we registered which males copulated in the field during 4 days and estimated the coloration of all observed males in the female visual spectrum. Surprisingly, we found that dull males had higher chances of copulation in A. hasemani, whereas in A. croceipennis male coloration did not influence the chances of copulation. Our data also indicated that brighter males of A. hasemani were also more conspicuous to potential avian predators, whereas this was not the case in A. croceipennis. We suggest that females of A. hasemani might avoid brighter males owing to increased risk of predation during copulation.

Rosyjskie słownictwo barw u kobiet i mężczyzn (badania wstępne)

The aim of the paper is to present the results of a study of psychological salience of colour terms for women and men who are native speakers of Russian. In our study, we employed the elicitation list task which is a five-minute psychological test designed to determine which and to what degree colour terms are psychologically important to language users. There were 26 Russian speakers – 13 women and 13 men – who participated in the test. The test results provide us with adequate material to be used to analyze both quantitative and qualitative differences between the female and male colour lexicons, and additionally, to estimate the scope of these differences. The study confirms the observations made by other researchers, as well as the popular opinion that women have a richer selection of colour words at their disposal and that they actually know many more metonymic colour terms than men.

Same Colors for Different Functions: Implications for the Evolution of Carotenoid-Based Ornamentation.

AbstractSexual ornamentation is often assumed to be costly, allowing honest signaling of individual quality, and carotenoid-based colors have been proposed to bear significant costs. If carotenoid-based colors are costly to produce, sexually selected signals should use more concentrated carotenoid pigments and have more saturated color than nonsexual signals, where honesty-guaranteeing costs are not required. We tested this prediction comparing carotenoid-based colors across canaries, goldfinches, and allies because many of these species use yellow plumage as sexual ornamentation but also have yellow rumps that appear to be nonsexual flash marks. Only in the breast, but not the rump, was there an asymmetric codistribution of male and female color saturation, with males similarly or more saturated than females, indicating evolution of breast color by sexual selection. Yellow was not consistently more saturated in the breast than in the rump, and the codistribution of rump and breast color saturation indicated that saturated rumps can persist irrespective of breast color. This challenges the assumption that carotenoid-based colors bear significant costs. The use of carotenoid coloration as sexual signals in this clade may instead be due to social costs, cost-free index mechanisms for signaling quality, and/or socially monogamous species evolving low-cost signals to mostly discriminate against the lowest-quality mates.

Cryptic species-level diversity in Dark-throated Oriole Oriolus xanthonotus

Borneo is part of the Sundaland biodiversity hotspot, yet this large tropical island still harbours much unrecognised biodiversity. In this integrative study, we combine the results from phylogenomic, bioacoustic, biometric and morphological analyses, and show that the Sundaic species Dark-throated Oriole Oriolus xanthonotus comprises two species-level taxa, both of which occur on Borneo. The eastern species, here re-named Ventriloquial Oriole O. consobrinus, is characterised by plumage distinctions, most notably a more male-like coloration in females, and a characteristic ventriloquial song unique among the region's orioles. The precise contact zone of the two species on Borneo is incompletely mapped. Their populations on Borneo show pronounced character displacement whereby individuals of O. xanthonotus on other landmasses are significantly larger than Bornean individuals, presumably to prevent non-adaptive hybridisation with the larger Ventriloquial Oriole along their Bornean contact zone.

A Novel Human Sex Difference: Male Sclera Are Redder and Yellower than Female Sclera.

In a seminal study, Kobayashi and Kohshima (1997) found that the human sclera-the white of the eye-is unique among primates for its whitish color, and subsequent work has supported the notion that this coloration underlies the human ability to gaze follow. Kobayashi and Kohshima also claimed that there is no significant sex difference in sclera color, though no data were presented to support the claim. We investigated sclera color in a standardized sample of faces varying in age and sex, presenting the first data comparing male and female sclera color. Our data support the claim that indeed there is a sex difference in sclera color, with male sclera being yellower and redder than female sclera. We also replicated earlier findings that female sclera vary in color across the adult lifespan, with older sclera appearing yellower, redder, and slightly darker than younger sclera, and we extended these findings to male sclera. Finally, in two experiments we found evidence that people use sclera color as a cue for making judgements of facial femininity or masculinity. When sclera were manipulated to appear redder and yellower, faces were perceived as more masculine, but were perceived as more feminine when sclera were manipulated to appear less red and yellow. Though people are typically unaware of the sex difference in sclera color, these findings suggest that people nevertheless use the difference as a visual cue when perceiving sex-related traits from the face.