Female Coloration Research Articles

ALOG/LSHs, a novel class of transcription factors: Evolutionarily conserved regulators of plant growth and development.

The ALOG/LSH group of proteins is highly conserved across plant lineage, starting from moss to higher flowering plants, suggesting their crucial role in the evolution and adaptation of land plants. The role of ALOG proteins is highly conserved in various developmental responses, such as vegetative and reproductive developmental programs. Their role in meristem identity, cotyledon development, seedling photomorphogenesis and leaf and shoot development has been relatively well established. Moreover, several key pieces of evidence suggest their role in inflorescence architecture and flower development, including male and female reproductive organs and flower colouration. Recent research has started to explore their role in stress response. Functionally, ALOG proteins have been demonstrated to act as transcriptional regulators and are considered a newly emerging class of transcription factors in plants that regulate diverse developmental and physiological processes. This review aims to stimulate discussion about their role in plant development and their role as transcription factors. It also aims to further unravel the underlying molecular mechanism by which they regulate growth and development throughout the plant lineage.

Exploiting floral signals: Olfactory crypsis and visual attraction in crab spider predatory strategies

AbstractPredation exerts a profound influence on the evolution of camouflage and detection abilities in both predators and prey. For instance, flower‐visiting spiders need to ensure their concealment when ambushing on flowers, which compels pollinators to check any spider cues cautiously before landing. Although numerous studies have examined the visual camouflage of spiders deceiving bees, little is known regarding whether spiders also employ olfactory camouflage. Additionally, the detection of spiders by dipteran insects is often overlooked, despite them being major non‐bee pollinators. Here, we explored the detection ability of dipteran pollinators and the crypsis skill of spiders from both olfactory and vision perspectives using the housefly Musca domestica L. (Diptera: Muscidae) as prey, the crab spider Ebrechtella tricuspidata (Fabricius) (Araneae: Thomisidae) as predators and chamomile Matricaria recutita L. (Asteraceae) as substrates. Our olfactory experiments revealed that experienced houseflies could respond to and avoid spider odour. However, this response did not appear to be innate, as naive individuals showed no aversion. Moreover, experienced houseflies did not have any avoidance behaviours to the mixed odours of spider and flower, indicating that spiders achieved olfactory crypsis utilizing floral scent. Our vision experiments and visual modelling demonstrated that houseflies could detect spiders positioned on flower. Surprisingly, instead of avoiding them, houseflies exhibited a preference for flowers occupied by female spiders, suggesting the attractive nature of female spider colouration. This paper provides evidence for the first time that crab spiders use floral scent to achieve olfactory crypsis and proposes a potential yellow‐signalling mechanism for crab spiders to attract insects.

Demography and natural history of the damselfly Mesamphiagrion gaudiimontanum (Coenagrionidae), a Páramo endemic species in the Colombian Andes

The páramos are high mountain ecosystems in the tropical regions of the New World, and they are particularly threatened by climate change. The Belmira páramo complex in Colombia is home to Mesamphiagrion gaudiimontanum, an endemic and endangered damselfly species. This study presents the first demographic assessment of M. gaudii­montanum using the capture-recapture method to estimate population size, survival, and detection probabilities, focusing on differences in age, sex, female color morphs, and parasite infestation. The population size was estimated to be 730 ± 186.59 individuals, with an average survival probability of 0.89 ± 0.04 and a life expectancy of 8.34 days, these data are like the reported for other populations in the same genus in harsh environmental conditions. Ectoparasitic mites were more common on juveniles than adults. After several hours of observing the species few copula events have been recorded, all of them involving juvenile adult females, which points to a monandrous reproduction syndrome for the species. Another phenomenon observed in the species was a change in coloration due to body temperature in individuals, in which bright coloration becomes grayish in cold weather. This study provides fundamental data for future monitoring and conservation efforts, highlighting the species’ vulnerability to environmental changes and the need for specific conservation strategies.

Developmental stage-dependent effects of perceived predation risk on nestling tree swallows (Tachycineta bicolor).

The risk of predation directly affects the physiology, behavior, and fitness of wild birds. Strong social connections with conspecifics could help individuals recover from a stressful experience such as a predation event; however, competitive interactions also have the potential to exacerbate stress. Few studies have investigated the interaction between environmental stressors and the social landscape in wild bird populations. In 2 years of field studies, we experimentally simulated predation attempts on breeding female tree swallows (Tachicyneta bicolor). At the same time, we manipulated female breast plumage color, a key social signal. Simulated predation events on tree swallows early in the nestling period reduced young nestlings' mass by approximately 20% and shortened telomere lengths. Ultimately, only 31% of nestlings in the predation group fledged compared with 70% of control nestlings. However, the effects of experimental manipulations were timing dependent: the following year when we swapped the order of the experimental manipulations and simulated predation during incubation, there were no significant effects of predation on nestling condition or fledging success. Contrary to our expectations, manipulation of the social environment did not affect the response of tree swallows to simulated predation. However, manipulating female plumage during the nestling period did reduce nestling skeletal size and mass, although the effects depended on original plumage brightness. Our data demonstrate that transient stressors on female birds can have carry-over effects on their nestlings if they occur during critical periods in the breeding season.

Orange ornamentation increases sex-specific conspicuousness of juvenile males to conspecifics and predators

Abstract Many animal species have evolved striking colour patterns that attract the opposite sex and intimidate rivals. Although conspicuous coloration is usually restricted to adults in the context of reproduction, this is not always the case. Juvenile collared lizards (Crotaphytus collaris) are sexually dichromatic, wherein males exhibit ‘dorsolateral bars’ that are bright orange and showy, whereas females are light tan and inconspicuous. Given that adult male collared lizards suffer increased predation because of bright adult coloration, we hypothesized that juvenile males might also be more detectable to predators owing to the conspicuousness of their dorsolateral bars. To test this hypothesis, we measured the reflectance of the dorsolateral bars, non-bar background body regions, and the rocky habitat in which the lizards live. We modelled the vision of our study species and its dominant predators to quantify and compare statistically the contrasts of male and female dorsolateral bars against the natural rock background. We also calculated lizard survivorship over a 4 year study period. We found that male orange bars exhibited significantly higher chromatic contrast, but significantly lower achromatic contrast, than female bars when perceived through all visual models. However, the dorsolateral background colour of juvenile males and females did not differ significantly in chromatic or achromatic contrast from rocks in any visual model. Female lizards survived better than male lizards to the yearling (reproductive) stage. Our findings indicate that juvenile male bars are conspicuous both to conspecifics and to predators and that the bars probably increase predation on juvenile males.

Variation in nuptial color in relation to sex, individual quality and mating success in the sex-role reversed Phalaropus fulicarius (Red Phalarope)

Abstract In most bird species, males are more ornamented and compete for females, who contribute more to offspring care. In a minority of species, this pattern is reversed, with more colorful females competing for mates and males taking care of parental duties. In such sex-role reversed species, the links between colorful ornamentation, individual quality and mating success are not well established. Phalaropus fulicarius (Red Phalarope) is a colorful sex-role reversed migratory shorebird with regular social polyandry, in which both sexes show considerable color variation. Here, we describe sex differences in color and quantify associations between color variation and indicators of quality and mating success in both sexes. Using a large sample of photos collected across 3 consecutive years on the Arctic breeding grounds, we scored color variation for 4 body parts (bill, crown, cheek, and breast), and analyzed scores separately and combined into an overall color score. Females were more colorful and larger than males, and individuals could be unambiguously sexed by crown color. Nevertheless, there was substantial variation within sexes and some overlap between males and females in bill, cheek, breast, and overall color scores. Assortative mating by color was only found for the bill. Color variation did not correlate with plasma testosterone levels, except for male cheek color. Females in better body condition had yellower bills and higher overall color scores, while early-arriving birds had higher breast and overall scores. Phalaropus fulicarius that bred locally were heavier than those that did not, but they did not have higher color scores. Female color variation did not predict the probability of local social polyandry nor variation in clutch size, and male coloration did not predict the probability of nest predation. In conclusion, P. fulicarius color variation showed modest correlations with individual quality and was unrelated to variation in local reproductive success.

Genetic Basis and Evolutionary Forces of Sexually Dimorphic Color Variation in a Toad-Headed Agamid Lizard.

In the animal kingdom, sexually dimorphic color variation is a widespread phenomenon that significantly influences survival and reproductive success. However, the genetic underpinnings of this variation remain inadequately understood. Our investigation into sexually dimorphic color variation in the desert-dwelling Guinan population of the toad-headed agamid lizard (Phrynocephalus putjatai) utilized a multidisciplinary approach, encompassing phenotypic, ultrastructural, biochemical, genomic analyses, and behavioral experiments. Our findings unveil the association between distinct skin colorations and varying levels of carotenoid and pteridine pigments. The red coloration in males is determined by a genomic region on chromosome 14, housing four pigmentation genes: BCO2 and three 6-pyruvoyltetrahydropterin synthases. A Guinan population-specific nonsynonymous single nucleotide polymorphism in BCO2 is predicted to alter the electrostatic potential within the binding domain of the BCO2-β-carotene complex, influencing their interaction. Additionally, the gene MAP7 on chromosome 2 emerges as a potential contributor to the blue coloration in subadults and adult females. Sex-specific expression patterns point to steroid hormone-associated genes (SULT2B1 and SRD5A2) as potential upstream regulators influencing sexually dimorphic coloration. Visual modeling and field experiments support the potential selective advantages of vibrant coloration in desert environments. This implies that natural selection, potentially coupled with assortative mating, might have played a role in fixing color alleles, contributing to prevalence in the local desert habitat. This study provides novel insights into the genetic basis of carotenoid and pteridine-based color variation, shedding light on the evolution of sexually dimorphic coloration in animals. Moreover, it advances our understanding of the driving forces behind such intricate coloration patterns.

Little evidence for color- or size-based mating preferences by male strawberry poison frogs (Oophaga pumilio)

While there are many studies documenting female mating preferences across taxa, male mate choice remains relatively understudied. Male mate choice often develops when there is variation in female quality and thus the fitness benefits of mating with particular females. Specifically, males tend to prefer females with traits that confer direct fitness benefits such as large body size, which may be linked with high fecundity. Prior work has shown that females of the strawberry poison frog, Oophaga pumilio, prefer males bearing certain coloration (most often the female’s own color), and that this preference can be learned through maternal imprinting. Females have been shown to prefer larger males as well. Here we test whether similar mate preferences for color and size exist in males of this species using two-way choice tests on captive bred male O. pumilio. In each test focal males were placed in an arena with two stimulus females: either both of the same size but differing in color, or both of the same color but differing in size. We found only weak evidence for behavioral biases toward particular colors and no evidence for biases toward larger females, suggesting that males of O. pumilio do not predictably choose mates based on these female traits. Despite several aspects of their natural history that suggest males have reasons to be choosy, our findings suggest that the cost of mate rejection may outweigh any fitness benefits derived from being selective of mates. Studies of additional populations, ideally conducted on wild individuals, are needed to better understand the range of conditions under which males may exhibit mate choice and the types of traits on which they base these choices.Significance statementTo fully understand the fitness landscapes and evolutionary trajectories that result from sexual selection, we need to understand when and how the mate preferences of the two sexes act and interact. While female mate choice has been widely studied, male mate choice remains poorly understood. To help bridge this gap, we studied male mate preferences in the strawberry poison frog Oophaga pumilio, a small brightly colored frog for which female preferences for male color and size have been well-documented. We found no evidence that male O. pumilio exhibit mate preferences based on female size and little evidence for male mate preferences based on female color. This is surprising given that larger females are often more fecund, male O. pumilio are known to exhibit color-based behavioral biases in the context of male-male competition, and both sexes provide parental care.

Genetic basis and expression of ventral colour in polymorphic common lizards.

Colour is an important visual cue that can correlate with sex, behaviour, life history or ecological strategies, and has evolved divergently and convergently across animal lineages. Its genetic basis in non-model organisms is rarely known, but such information is vital for determining the drivers and mechanisms of colour evolution. Leveraging genetic admixture in a rare contact zone between oviparous and viviparous common lizards (Zootoca vivipara), we show that females (N = 558) of the two otherwise morphologically indistinguishable reproductive modes differ in their ventral colouration (from pale to vibrant yellow) and intensity of melanic patterning. We find no association between female colouration and reproductive investment, and no evidence for selection on colour. Using a combination of genetic mapping and transcriptomic evidence, we identified two candidate genes associated with ventral colour differentiation, DGAT2 and PMEL. These are genes known to be involved in carotenoid metabolism and melanin synthesis respectively. Ventral melanic spots were associated with two genomic regions, including a SNP close to protein tyrosine phosphatase (PTP) genes. Using genome re-sequencing data, our results show that fixed coding mutations in the candidate genes cannot account for differences in colouration. Taken together, our findings show that the evolution of ventral colouration and its associations across common lizard lineages is variable. A potential genetic mechanism explaining the flexibility of ventral colouration may be that colouration in common lizards, but also across squamates, is predominantly driven by regulatory genetic variation.

Evolution in Islands: contrasting morph frequencies in damselfly populations of the Balearic Islands

Abstract Colour polymorphism is an example of visible phenotypic variability that is often associated with ecological factors and may produce local adaptations. Small populations, particularly in islands, offer opportunities for evolutionary novelties, and are therefore of particular interest to the study of polymorphisms. Here we study the dynamics of female colour morphs in the damselfly Ischnura elegans in the Balearic Islands. We found that insular populations are small, show low density, low mating activity, and low androchrome frequency. Our surveys suggest that male harassment is a powerful force in the dynamics of this female-limited polymorphism, because high male densities result in lower presence of mature females around the water, where copulation takes place. Non-male-like (infuscans) females have higher mating frequency. Androchromes were rare (15%) in all populations, but the frequency of the two non-male like females (infuscans and aurantiaca) was reversed between islands, despite their geographical proximity. We found a possible novel morph, suggesting that insular conditions allow innovations. Fitness differences between the two non-male-like females of I. elegans are still understudied, because most previous research has concentrated on the maintenance of androchromes, and are therefore a priority for future research.

Observation of heterospecific mating attempt of Blue Chaser <i>Libellula fulva</i> Müller, 1764 and Broad-bodied Chaser <i>L. depressa</i> Linnaeus, 1758 (Anisoptera: Libellulidae)

A successful copula formation between a male of Libellula fulva and a female of L. depressa was documented photographically on 23. 6. 2022 at a small stream in the Natura 2000 site Ličenca pri Poljčanah in NE Slovenia. This represents the first record of an anomalous mating attempt with copula formation between the species involved. Their distribution in Slovenia as well as syntopic and syntemporal observations in the country are presented and briefly discussed, as are the site-specific factors and aged female coloration that may have contributed to the described rare attempt of heterospecific mating.

Global patterns of plumage color evolution in island-living passeriform birds

Island environments have the potential to change evolutionary trajectories of morphological traits in species relative to their mainland counterparts due to habitat and resource differences, or by reductions in the intensity of social or sexual selection. Latitude, island size, and isolation may further influence trait evolution through biases in colonization rates. We used a global dataset of passerine plumage color as a model group to identify selective pressures driving morphological evolution of island animals using phylogenetically-controlled analyses. We calculated chromaticity values from red and blue scores extracted from images of the majority of Passeriformes and tested these against the factors hypothesized to influence color evolution. In contrast to predictions based on sexual and social selection theory, we found consistent changes in island female color (lower red and higher blue chromaticity), but no change in males. Instead, island size and distance from mainland and other islands influenced color in both sexes, reinforcing the importance of island physiognomy in shaping evolutionary processes. Interactions between ecological factors and latitude also consistently influenced color for both sexes, supporting a latitudinal gradient hypothesis. Finally, patterns of color evolution varied among families, indicating taxon-specific microevolutionary processes in driving color evolution. Our results show island residency influences color evolution differently between sexes, but the patterns in both sexes are tempered by ecological, island characteristics, and phylogenetic effects that further vary in their importance among families. The key role of environmental factors in shaping bird plumage on islands further suggests a reduced importance of sexual and social factors in driving color evolution.

Ultrastructural analysis of throat dermal tissue and chromatophore components in the threespine stickleback (Gasterosteus aculeatus).

The threespine stickleback (Gasterosteus aculeatus) is an important model for studying the evolution of nuptial coloration, but histological analyses of color are largely lacking. Previous analyses of one nuptial coloration trait, orange-red coloration along the body, have indicated carotenoids are the main pigment producing this color. In addition, recent gene expression studies found variation in the correlates of throat coloration between the sexes and between populations, raising the possibility of variation in the mechanisms underlying superficially similar coloration. We used transmission electron microscopy (TEM) to investigate the histological correlates of color in the throat dermal tissue of threespine stickleback from Western North America, within and between sexes, populations, and ecotypes. Ultrastructural analysis revealed carotenoid-containing erythrophores to be the main chromatophore component associated with orange-red coloration in both males and females across populations. In individuals where some darkening of the throat tissue was present, with no obvious orange-red coloration, erythrophores were not detected. Melanophore presence was more population-specific in expression, including being the only chromatophore component detected in a population of darker fish. We found no dermal chromatophore units within colorless throat tissue. This work confirms the importance of carotenoids and the erythrophore in producing orange-red coloration across sexes, as well as melanin within the melanophore in producing darkened coloration, but does not reveal broad histological differences among populations with similar coloration.

Losses of sexual dichromatism involve rapid changes in female plumage colors to match males in New World blackbirds.

Differences in coloration between the sexes (sexual dichromatism) can increase or decrease in a species through evolutionary changes in either or both sexes diverging or converging in their colors. Few previous studies, however, have examined the relative rates of such changes, particularly when dichromatism is lost. Using reflectance data from 37 species of the New World blackbird family (Icteridae), we compared evolutionary rates of plumage color change in males and females when dichromatism was either increasing (colors diverging) or decreasing (colors converging). Increases in dichromatism involved divergent changes in both sexes at approximately equal rates. Decreases in dichromatism, in contrast, involved changes in females to match male plumage colors that were significantly more rapid than any changes in males. Such dramatic changes in females show how selection can differ between the sexes. Moreover, these evolutionary patterns support the idea that losses of dimorphism involve genetic mechanisms that are already largely present in both sexes, whereas increases in dimorphism tend to involve the appearance of novel sex-specific traits, which evolve more slowly. Our results have broad implications for how sexual dimorphisms evolve.

First record of Neoscona xishanensis Yin, Wang, Xie et Peng, 1990 (Araneae: Araneidae) from India with description of hitherto unknown male

Neoscona xishanensis Yin, Wang, Xie et Peng, 1990 is recorded from India (Himachal Pradesh: Lahaul) for the first time. Hitherto unknown male of this species is described. Variation of the female abdominal color patterns is also discussed.

Discriminatory episodes negatively impact the quality of life of Brazilian dental students: A cross-sectional study.

This study aimed to evaluate whether discriminatory episodes occurring in the university environment were associated with dental students' self-perceived overall quality of life and assess the cumulative effect of perceived discriminatory experiences on the overall quality of life. In this cross-sectional study, all students enrolled in three Brazilian dental schools were invited to participate in a survey between August and October 2019. The outcome was students' self-perceived quality of life, measured through the overall quality of life item of the World Health Organization-Quality of Life Abbreviated Version (WHOQOL-BREF). Descriptive, bivariate, and multivariable logistic regression analyses (95% confidence intervals and α of 5%) were conducted using RStudio software. The sample was composed of 732 students (70.2% response rate). The great part was female (66.9%), white or yellow skin color (67.9%), and were children of highly educated mothers. About 68% of the students reported having experienced at least one of the seven discriminatory experiences presented in the questionnaire and 18.1% reported neutral or negative quality of life. In multivariable analyses, it was estimated that students who experienced at least one episode of discrimination were 2.54 times (95% CI: 1.47-4.34) more likely to report worse quality of life than their counterparts who reported no experience of discrimination. There was also a 25% (95% CI: 1.10-1.42) increase in the odds of reporting poorer quality of life for each additional discriminatory experience reported. Reporting at least one discriminatory situation in the academic environment was associated with worse quality of life among dental students, and a cumulative effect was also noted.

The extent of rapid colour change in male agamid lizards is unrelated to overall sexual dichromatism

AbstractDynamic colour change is widespread in ectothermic animals, but has primarily been studied in the context of background matching. For most species, we lack quantitative data on the extent of colour change across different contexts. It is also unclear whether and how colour change varies across body regions, and how overall sexual dichromatism relates to the extent of individual colour change. In this study, we obtained reflectance measures in response to different stimuli for males and females of six species of agamid lizards (Agamidae, sister family to Chameleonidae) comprising three closely related species pairs. We computed the colour volume in a lizard‐vision colour space occupied by males and females of each species and estimated overall sexual dichromatism based on the area of non‐overlapping male and female colour volumes. As expected, males had larger colour volumes than females, but the extent of colour change in males differed between species and between body regions. Notably, species that were most sexually dichromatic were not necessarily those in which males showed the greatest individual colour change. Our results indicate that the extent of colour change is independent of the degree of sexual dichromatism and demonstrate that colour change on different body regions can vary substantially even between pairs of closely related species.

Examining causes and characteristics of egg ejection behaviour in the American robin (Turdus migratorius)

Abstract American robins (Turdus migratorius) are among few hosts of parasitic brown-headed cowbirds (Molothrus ater) that frequently eject foreign eggs from their nests. However, we know little about some characteristics of the robins’ egg ejection process including its distance and direction. We used a novel technique (i.e., radio transmitters inserted into 3D-printed eggshells) to examine egg rejection in female robins as a function of model egg coloration (i.e., robin-mimetic blue, non-mimetic deep blue, and non-mimetic beige). Based on prior work, we predicted that female robins’ egg ejection decisions would be dependent on egg coloration. Accordingly, we found a significant effect of female identity (using nest identity as a proxy) and model egg colour on egg ejection, but neither predicted ejection distance or direction. Deep blue model eggs had shorter ejection latencies than beige eggs. Fully characterizing the egg ejection process will allow us to further understand the mechanisms and outcomes of egg ejection behaviours in host-parasite interactions.

The signalling function of plumage colour traits in the Chestnut Thrush (Turdus rubrocanus)

Melanin is a common pigment in birds, and several studies have shown that melanin‐based plumage coloration could signal individual body condition, social status and personality traits. However, most of these studies have focused on males, and little is known about the role of plumage coloration in females. Here, we investigated whether body condition and personality traits (activity and exploratory behaviour) were associated with plumage coloration in wild populations of the Chestnut Thrush Turdus rubrocanus, an apparently monochromatic species. We also tested whether the signals of plumage colour traits differed between sexes. In this study, we found that females had better body condition compared with males. Females with lower chroma and brightness of their black wings had better body condition, but no plumage colour measures reflected male body condition. Males with a lower red chroma of their brown back plumage were less active, and females with lower red chroma of the back plumage were more active. However, plumage coloration did not explain variation in exploratory behaviour. Our findings suggest that plumage colour traits may act as sex‐specific signals in Chestnut Thrushes and these traits may play important roles in sexual or conspecific communication in the wild.

Impact of genetic relatedness on reproductive behavior in Pelvicachromis pulcher, a biparental cichlid fish with mutual mate choice and ornamentation

Inbreeding can result in inbreeding depression. Therefore, many species seek to avoid inbreeding. However, theory predicts that inbreeding can be beneficial. Accordingly, some species tolerate inbreeding or even prefer mating with close relatives. Evidence for active inbreeding, i.e., kin-mating preference was reported in the biparental African cichlid fish Pelvicachromis taeniatus. Related mating partners revealed better parental cooperation due to kin selection, a potential benefit of inbreeding. In this study, we investigated kin-mating preference in a genetically diverse, outbred F2-lab population of Pelvicachromis pulcher, a closely related species to P. taeniatus. Like P. taeniatus, this species shows mutual ornamentation and mate choice as well as intense biparental brood care. The F1 P. pulcher generation had revealed signs of inbreeding depression but no inbreeding avoidance. We studied mating behavior and aggression in trios consisting of a male P. pulcher, an unfamiliar sister, and an unfamiliar, unrelated female. Because the study focused on kin-mating patterns, female pairs were matched for body size and coloration. The results provide no evidence for inbreeding avoidance but rather suggest inbreeding preference. We also found no significant impact of inbreeding on offspring survival. The results suggest no inbreeding avoidance in P. pulcher; however, the strength of inbreeding preference and inbreeding depression seems to be variable. We discuss possible causes for this variation like context-dependent inbreeding depression. The number of eggs positively correlated with female body size and coloration. Furthermore, the female aggressiveness was positively correlated with female coloration indicating that coloration signal female dominance and quality.