Body Color Variation Research Articles

A preliminary identification of genomic loci for body colour variation in the sea cucumberApostichopus japonicus

The sea cucumber Apostichopus japonicus is one of the most economically important aquaculture species in China, which shows a distinct characteristic of body colour variation. A number of purple variants were obtained in the coast of China, which shows great potential to develop a niche market. In the present study, to understand the genetic basis of green-purple colour variation, a genome-wide association study based on the 2b-RAD sequencing was conducted. As a result, 8,795 genome-wide single nucleotide polymorphism (SNP) markers were obtained and then applied to the association analysis. Ten most associated SNP loci with p-value <1.0 × 10–8 were obtained, and they were assigned to 4 chromosomes (chr17, chr21, chr15 and chr05). In genomic regions neighbouring to those SNPs, 33 candidate genes with annotation were obtained and the endothelin-converting enzyme-1, which was reported to be involved in pigmentation variation, was identified. To our knowledge, this is the first report of the genetic locus for body colour variation in this species. These findings will be useful for the fine mapping of the determining gene for body colour variation of A. japonicus.

Female polymorphism in Chilothrips strobilus (Thysanoptera: Thripidae), with the first description of the male.

Polymorphism and sexual dimorphism are common in insects. Thrips have been reported to exhibit intraspecific variation in body size, color and wing length (Mound 2005), also sexual dimorphism in abdominal pore plates, antennal sensoria and fore leg armature (Tyagi et al. 2008). Chilothrips Hood is a small genus that currently comprises seven species (ThripsWiki 2017), three from USA, one from Japan, and three from China. No male has been reported in the three species from China, C. strobilus, C. jiuxiensis and C. hangzhouensis (Hu & Feng 2015), and C. strobilus was described on three female specimens from cones of Pinus in Liaoning Province, northeastern China (Tong & Zhang, 1994). Recently, we have surveyed different parts of northeastern China and collected many male individuals of C. strobilus. We have observed that this species shows sexual dimorphism in mouth cone length, and remarkable variation in form of abdominal segment X among females.

Comparative Transcriptome and DNA methylation analyses of the molecular mechanisms underlying skin color variations in Crucian carp (Carassius carassius L.)

BackgroundCrucian carp is a popular ornamental strain in Asia with variants in body color. To further explore the genetic mechanisms underlying gray and red body color formation in crucian carp, the skin transcriptomes and partial DNA methylation sites were obtained from red crucian carp (RCC) and white crucian carp (WCC). Here, we show significant differences in mRNA expression and DNA methylation sites between skin tissues of RCC and WCC.ResultsTotals of 3434 and 3683 unigenes had significantly lower and higher expression in WCC, respectively, compared with unigenes expressed in RCC. Some potential genes for body color development were further identified by quantitative polymerase chain reaction, such as mitfa, tyr, tyrp1, and dct, which were down-regulated, and foxd3, hpda, ptps, and gch1, which were up-regulated. A KEGG pathway analysis indicated that the differentially expressed genes were mainly related to mitogen activated protein kinase (MAPK), Wnt, cell cycle, and endocytosis signaling pathways, as well as variations in melanogenesis in crucian carp. In addition, some differentially expressed DNA methylation site genes were related to pigmentation, including mitfa, tyr, dct, foxd3, and hpda. The differentially expressed DNA methylation sites were mainly involved in signaling pathways, including MAPK, cAMP, endocytosis, melanogenesis, and Hippo.ConclusionsOur study provides the results of comparative transcriptome and DNA methylation analyses between RCC and WCC skin tissues and reveals that the molecular mechanism of body color variation in crucian carp is strongly related to disruptions in gene expression and DNA methylation during pigmentation.

Genetic analysis of a red tilapia (Oreochromis spp.) population undergoing three generations of selection for increased body weight at harvest

Quantitative genetic analysis was performed on 10,919 data records collected over three generations from the selection programme for increased body weight at harvest in red tilapia (Oreochromis spp.). They were offspring of 224 sires and 226 dams (50 sires and 60 dams per generation, on average). Linear mixed models were used to analyse body traits (weight, length, width and depth), whereas threshold generalised models assuming probit distribution were employed to examine genetic inheritance of survival rate, sexual maturity and body colour. The estimates of heritability for traits studied (body weight, standard length, body width, body depth, body colour, early sexual maturation and survival) across statistical models were moderate to high (0.13-0.45). Genetic correlations among body traits and survival were high and positive (0.68-0.96). Body length and width exhibited negative genetic correlations with body colour (-0.47 to -0.25). Sexual maturity was genetically correlated positively with measurements of body traits (weight and length). Direct and correlated genetic responses to selection were measured as estimated breeding values in each generation and expressed in genetic standard deviation units (σG). The cumulative improvement achieved for harvest body weight was 1.72 σG after three generations or 12.5% per generation when the gain was expressed as a percentage of the base population. Selection for improved body weight also resulted in correlated increase in other body traits (length, width and depth) and survival rate (ranging from 0.25 to 0.81 genetic standard deviation units). Avoidance of black spot parent matings also improved the overall red colour of the selected population. It is concluded that the selective breeding programme for red tilapia has succeeded in achieving significant genetic improvement for a range of commercially important traits in this species, and the large genetic variation in body colour and survival also shows that there are prospects for future improvement of these traits in this population of red tilapia.

Three Cases of Anomalously White Risso's DolphinsGrampus griseusin Japan

Three male anomalously white Risso's dolphins Grampus griseus were observed in the waters off Taiji, Wakayama, Japan. One (GG-1) was captured alive in 2007, and the other two (GG-2 and GG-3) were captured in 2014. The color pattern of GG-1 is approximately divided into two parts; the middle of the trunk and the lower part of the dorsal fin are white, whereas the anterior and caudal portions have dark pigmentations. GG-2 has an almost white body with some dark pigmentation in the head region, and GG-3 has a completely white body with some sparse dark flecks around the throat. All three dolphins have dark eyes similar to a normally pigmented Risso's dolphin; however, the oral mucosa of GG-2 and GG-3 and the mucosa in the blowhole of GG-3 are white to pinkish in color without any dark pigmentation. Furthermore, the mucosa in the blowhole of GG-2 is a mixture of white patches and dark pigmentation. These three dolphins are the first anomalously white Risso's dolphins to be kept in captivity; therefore they are valuable for understanding the cause of body color variations and the anomalous coloration effects in animals.

Individual variation in body color in the field cricket Teleogryllus occipitalis (Orthoptera: Gryllidae)

AbstractBody color of animals may affect individual fitness through direct effects on various processes, such as predatory avoidance, thermoregulation, UV resistance, and mating behavior. Body color variation of the field cricket Teleogryllus occipitalis (Audinet‐Serville) (Orthoptera: Gryllidae) is often observed. We quantified the individual variation in body color of this species by measuring the luminance of hind leg femur. Thereafter, we examined whether the body color was a heritable trait or not using parent–offspring analysis. In addition, the effect of body color of both parents on body size, sex ratio, and survival rate of progeny was investigated. The results showed that maternal body color was not heritable, whereas paternal body color was correlated with the body color of the progeny. Body size and sex ratio were not correlated with body color of parents. Although paternal body color did not affect the survival rate of the progeny beyond the stage of final instar nymph, progeny survival rate significantly increased with darkness of maternal body.

The Environmental Plasticity of Diverse Body Color Caused by Extremely Long Photoperiods and High Temperature in Saccharosydne procerus (Homoptera: Delphacidae).

Melanization reflects not only body color variation but also environmental plasticity. It is a strategy that helps insects adapt to environmental change. Different color morphs may have distinct life history traits, e.g., development time, growth rate, and body weight. The green slender planthopper Saccharosydne procerus (Matsumura) is the main pest of water bamboo (Zizania latifolia). This insect has two color morphs. The present study explored the influence of photoperiod and its interaction with temperature in nymph stage on adult melanism. Additionally, the longevity, fecundity, mating rate, and hatching rate of S. procerus were examined to determine whether the fitness of the insect was influenced by melanism under different temperature and photoperiod. The results showed that a greater number of melanic morphs occurred if the photoperiod was extremely long. A two-factor ANOVA showed that temperature and photoperiod both have a significant influence on melanism. The percentages of variation explained by these factors were 45.53 and 48.71%, respectively. Moreover, melanic morphs had greater advantages than non-melanic morphs under an environmental regime of high temperatures and a long photoperiod, whereas non-melanic morphs were better adapted to cold temperatures and a short photoperiod. These results cannot be explained by the thermal melanism hypothesis. Thus, it may be unavailable to seek to explain melanism in terms of only one hypothesis.

Melanin pigmentation gives rise to black spots on the wings of the silkworm Bombyx mori

Several mutants of the silkworm Bombyx mori show body color variation at the larval and adult stages. The Wild wing spot (Ws) mutant exhibits a phenotype in which the moth has a spot on the apex of the forewing. In this study, we investigated this trait to elucidate the molecular mechanism underlying the color pattern. Microscopy of the black spot of Ws mutants showed that the pigment emerges in the scales of the wing, and accumulation of the pigment becomes strong just before eclosion. We next examined the relationship between the black spot of the Ws mutant and melanin. The spectrophotometry using alkaline extracts from the black spot in the wing showed the highest absorption intensity at 405nm, which is the absorbance wavelength of melanin. Moreover, inhibition assays for enzymes implicated in melanin synthesis using 3-iodo-l-tyrosine (a tyrosine hydroxylase inhibitor) and L-α-methyl-DOPA (a dopa decarboxylase inhibitor) revealed that treatment with each inhibitor disrupted the pigmentation of the wing of the Ws mutant. On the basis of these results, we analyzed the expression pattern of five genes involved in melanin formation, and found that the expression levels of yellow and laccase2 were increased just before pigmentation, whereas those of DDC, tan, and TH were increased when the apex of the wing turned black. These results showed that melanin pigmentation gives rise to the black spot on the wing.

Effects of substrate color on the body color variation of two agamid lizards, Phrynocephalus versicolor and P. frontalis

Geographical variation of body color is widely present in reptile populations that survive in different substrate habitats, multiple potential mechanisms can account for this color variation. Phrynocephalus versicolor and P. frontalis, close genetic relatives, constitute a phylogenetic species group together with P. przewalskii. In this study, a fiber spectrophotometer (AvaSpec-2048) was used to record the skin luminous reflectivity of 12 sites across the lizard’s body, and we quantitatively compared the natural color variation of dark P. versicolor and light P. frontalis that lived in “melanistic” and “non-melanistic” habitats, respectively. We aimed to determine whether the color variations of both populations were time reversible, and further discuss potential mechanisms that substrate color may have on color variation of Phrynocephalus lizards. Our results showed that the body color of P. versicolor in “melanistic” habitat was significantly darker than P. frontalis in the “non-melanistic” withered yellow habitat. We also conducted a reciprocal transplantation experiments (i.e. “non-melanistic” withered yellow P. frontalis individuals were transplanted and fed in “melanistic” substrate environment, while “melanistic” P. versicolor individuals were transplanted and fed in withered yellow substrate environment). For “melanistic” P. versicolor, the skin reflectivity of six sites increased significantly after one week, while no significant changes were detected in other sites. For “non-melanistic” P. frontalis, except the skin reflectivity of two sites (left hind limb and top right on the •研究报告• 1040 生 物 多 样 性 Biodiversity Science 第 24 卷 back) significantly changed, compared to corresponding values one week previously, other sites showed no significant changes. Our results suggest that P. versicolor possesses stronger color variation ability than P. frontalis, and the color phenotypes are likely inherited in both species. Short-term changes of substrate color can cause slightly color variations that are difficult to distinguish by naked eyes, suggesting ontogeny related hereditary factors may also play a controlling role.

A new species of tree crickets (Orthoptera, Gryllidae, Oecanthinae) in tobacco plantation from Southern Brazil, with body color variation

A new species of tree crickets (Orthoptera, Gryllidae, Oecanthinae) in tobacco plantation from Southern Brazil, with body color variation

A role for ecology in the evolution of colour variation and sexual dimorphism in Hawaiian damselflies.

Variation in traits that are sexually dimorphic is usually attributed to sexual selection, in part because the influence of ecological differences between sexes can be difficult to identify. Sex-limited dimorphisms, however, provide an opportunity to test ecological selection disentangled from reproductive differences between the sexes. Here, we test the hypothesis that ecological differences play a role in the evolution of body colour variation within and between sexes in a radiation of endemic Hawaiian damselflies. We analysed 17 Megalagrion damselflies species in a phylogenetic linear regression, including three newly discovered cases of species with female-limited dimorphism. We find that rapid colour evolution during the radiation has resulted in no phylogenetic signal for most colour and habitat traits. However, a single ecological variable, exposure to solar radiation (as measured by canopy cover) significantly predicts body colour variation within sexes (female-limited dimorphism), between sexes (sexual dimorphism), and among populations and species. Surprisingly, the degree of sexual dimorphism in body colour is also positively correlated with the degree of habitat differences between sexes. Specifically, redder colouration is associated with more exposure to solar radiation, both within and between species. We discuss potential functions of the pigmentation, including antioxidant properties that would explain the association with light (specifically UV) exposure, and consider alternative mechanisms that may drive these patterns of sexual dimorphism and colour variation.

Body-colour variation in an orb-web spider and its effect on predation success

Animal body coloration serves several functions such as thermoregulation, camouflage, aposematism, and intraspecific communication. In some orb-web spiders, bright and conspicuous body colours are used to attract prey. On the other hand, there are other species whose body colour does not attract prey. Using a spider species showing individual body-colour variation, the present study aimed to determine whether or not the variation in body colour shows a correlation with predation rates. We studied the orb-web spider (Cyclosa argenteoalba) using both field observations and T-maze experiments, in which the prey were exposed to differently coloured spiders. Cyclosa argenteoalba has silver- and black-coloured areas on its dorsal abdomen, with the ratio of these two colours varying continuously among individuals. The bright and conspicuous silver area reflects ultraviolet light. Results of both field observations and colour choice experiments using Drosophila flies as prey showed that darker spiders have a greater chance of capturing prey than silver spiders. This indicates that body-colour variation affects predation success among individuals and that the bright silver colour does not function to attract prey in C. argenteoalba.

First observations of fertilized eggs and preleptocephalus larvae ofRhinomuraena quaesitain the Vienna Zoo

For the first time worldwide, fertilized eggs of ribbon eels (Rhinomuraena quaesita) hatched into feeding preleptocephali and could be kept alive for a period of seven days in the Vienna Zoo. The study reports on husbandry, behavioral observations and dimensions of eggs and preleptocephalus larvae. Furthermore, body color variations of ribbon eels in captivity do not reflect its sex or sexual maturity.

Isolation and expression analysis of Sox10 gene relating body color variation in Oujiang color common carp

Isolation and expression analysis of Sox10 gene relating body color variation in Oujiang color common carp

Causes of polymorphic melanism and its thermoregulatory function in a parasitoid wasp Meteorus pulchricornis (Hymenoptera: Braconidae)

We investigated the variation in body colour and its thermoregulatory function in Meteorus pulchricornis (Wesmael) (Hymenoptera: Braconidae), a parasitoid wasp of Spodoptera and other free-living lepidopteran larvae. We show that the body colour of adult wasps darkens when cocoons are kept at low temperatures. The range in the variation in colour, however, differs for different parts of the body and among uniparental (thelytokous) strains. This melanism enables these wasps to attain a body temperature in sunshine up to 2°C. Moreover, this small gain in body temperature can markedly increase the flight activity of wasps at low ambient temperatures. We conclude that the variation in body colour that resulted from rearing the cocoons at different temperatures enable the wasps to adapt to changing thermal environments. The ecological significance of the difference in the degree of melanism of the different strains is discussed.

Looking for ‘identity signatures’ in the American lobster (Homarus americanus): Interindividual variation in body colour and in facial and chelar morphology

Previous studies have shown that the American lobster, Homarus americanus, is able to recognize the identity of conspecifics. To be recognized, a lobster should bear unique phenotypic traits that are unlikely to be confused in the population. Our aim here was to investigate, in H. americanus, some variable phenotypes that could be good candidates for ‘identity signatures’. Five colour parameters of 44 spots distributed on the body of 12 adult males were measured. We also measured 10 features of the face in 13 adult male lobsters, and 7 and 5 features of the crusher and the cutter chelae, respectively, in 8 of these individuals. Principal Component Analyses showed a clear interindividual difference in colour patterns and a large variation of facial and chelar morphology. The most variable features were: the shape of the face plus the size and distance between the eyes and the orbital spines; the number, size and shape of the molar-like teeth of the crusher chelae plus the number of its spines; and the size of the dactyl of the cutter chelae plus the number of its incisor-like teeth and spines. Obviously, before concluding that colour and morphological features are identity signatures in H. americanus, behavioural studies and an increased knowledge of visual acuity and colour sensitivity in this species are needed. Nevertheless, the similarity of our results with findings on the crayfish Cherax destructor is intriguing and stimulates further research.

Ecology, genetics, and evolution of body color variations

Ecology, genetics, and evolution of body color variations

Predation and the relative importance of larval colour polymorphisms and colour polyphenism in a damselfly

Intraspecific body colour variation is common in many animal species. Predation could be a key selective agent giving rise to variation in body colour, and such variation could be due to genetics ( ...

Adding parasites to the guppy-predation story: insights from field surveys

Studies of phenotypic variation in nature often consider only a single potential selective agent. In such cases, it remains an open question as to whether variation attributed to that single measured agent might be influenced by some other unmeasured agent. Previous research has shown that phenotypic variation in the Trinidadian guppy (Poecilia reticulata) is strongly influenced by predation regime, and we here ask whether parasitism might represent an additional important selective agent shaping this variation. We performed a field survey of 26 natural guppy populations of known predation regime in northern Trinidad. We quantified levels of parasitism of guppies by the monogenean ecotoparasite, Gyrodactylus, and examined whether this parasite was associated with guppy body size or male colour. Spatial variation in Gyrodactylus parasitism was consistent between years, and parasite prevalence was generally, but not always, higher at high-predation sites than at low-predation sites. Consistent with previous work, predation regime was related to guppy size and some aspects of male colour, whereas parasitism showed few and only minor associations with the same traits. Moreover, a consideration of parasitism did not alter any interpretations regarding associations between guppy traits and predation regimes. These results suggest that parasitism, at least as quantified in the present study, does not play a major role in shaping variation in guppy body size or colour. Nevertheless, considerable variation in these traits, even within a predation regime, suggests the likely importance of other selective agents beyond just predation regime.

Genetic analysis of body color phenotypes in the fruit flyDrosophila melanogaster: supporting evidence through laboratory-selected dark and light strains

In the fruit fly Drosophila melanogaster Meigen, 1830, abdominal melanisation varies in a quantitative manner, but little attention has been paid to the genetic basis of different phenotypic classes and their ecological significance in the wild populations. Laboratory-selected darker and lighter body color strains were used for determining the genetic basis of body color phenotypes. Based on such genetic characterization, we interpreted body color variation of wild flies collected along a latitudinal gradient. Our results are interesting in several respects. First, laboratory selection produced lighter females and also lighter males, in contradiction of the well-known sexual dimorphism in D. melanogaster. The laboratory-selected darker and lighter strains showed lack of phenotypic plasticity, whereas F1flies from reciprocal crosses showed significant levels of phenotypic plasticity. Second, for both sexes, F2phenotypic classes resulting from reciprocal crosses between selected darker and lighter strains fit a two-locus model with a stronger maternal effect in males than in females. Third, changes in continuously varying abdominal melanisation of wild-caught flies were sorted into phenotypic bins of body color phenotypic classes and such data on geographical populations of D. melanogaster are consistent with climatic selection. Thus, we may suggest that for ecological genetic studies, greater emphasis should be laid on the analysis of bins of phenotypic classes of body melanisation in laboratory and wild populations of D. melanogaster.