Spectral Sensitivities and Color Signals in a Polymorphic Damselfly

Insect body colors and patterns change markedly during development in some species as they adapt to their surroundings. The contribution of melanin and sclerotin pigments, both of which are synthesized from dopamine, to cuticle tanning has been well studied. Nevertheless, little is known about how insects alter their body color patterns. To investigate this mechanism, the cricket Gryllus bimaculatus, whose body color patterns change during postembryonic development, was used as a model in this study. We focused on the ebony and tan genes, which encode enzymes that catalyze the synthesis and degradation, respectively, of the precursor of yellow sclerotin N-β-alanyl dopamine (NBAD). Expression of the G. bimaculatus (Gb) ebony and tan transcripts tended to be elevated just after hatching and the molting period. We found that dynamic alterations in the combined expression levels of Gb’ebony and Gb’tan correlated with the body color transition from the nymphal stages to the adult. The body color of Gb’ebony knockout mutants generated by CRISPR/Cas9 systemically darkened. Meanwhile, Gb’tan knockout mutants displayed a yellow color in certain areas and stages. The phenotypes of the Gb’ebony and Gb’tan mutants probably result from an over-production of melanin and yellow sclerotin NBAD, respectively. Overall, stage-specific body color patterns in the postembryonic stages of the cricket are governed by the combinatorial expression of Gb’ebony and Gb’tan. Our findings provide insights into the mechanism by which insects evolve adaptive body coloration at each developmental stage.

Damselfishes (Pomacentridae) are widespread and highly abundant on tropical coral reefs. They exhibit diverse body colouration within and between the ~250 species and across ontogenetic stages. In addition to human-visible colours (i.e., 400-700 nm), most adult damselfishes reflect ultraviolet (UV, 300-400 nm) colour patches. UV sensitivity and UV colour signals are essential for feeding and form the basis for a secret communication channel invisible to the many UV-blind predatory fish on the reef; however, how these traits develop across ontogenetic stages and their distribution across the damselfish family is poorly characterised. Here, we used UV photography, phylogenetic reconstructions of opsin genes, and differential gene expression analysis (DGE) of retinal samples to investigate the development of UV vision and colour patterns in three ontogenetic stages (pre-settlement larval, juvenile, and adult) of 11 damselfish species. Using DGE, we found similar gene expression between juveniles and adults, which strongly differed from larvae. All species and all stages expressed at least one UV-sensitive sws1 opsin gene. However, UV body colour patterns only started to appear at the juvenile stage. Moreover, Pomacentrus species displayed highly complex UV body patterns that were correlated with the expression of two sws1 copies. This could mean that some damselfishes can discriminate colours that change only in their UV component. We demonstrate dramatic shifts in both UV sensitivity and UV colouration across the development stages of damselfish while highlighting the importance of considering ontogeny when studying the coevolution of visual systems and colour signals.

Many insects, including several orthopterans, undergo dramatic changes in body coloration during ontogeny. This variation is particularly intriguing in gomphocerine grasshoppers, where the green and brown morphs appear to be genetically determined (Schielzeth & Dieker, 2020, BMC Evolutionary Biology, 20, 63; Winter etal., 2021, Heredity, 127, 66). A better understanding of how these color morphs develop during ontogeny can provide valuable insights into the evolution and ecology of such a widespread color polymorphism. Here, we focus on the color development of two green-brown polymorphic species, the club-legged grasshopper Gomphocerus sibiricus and the steppe grasshopper Chorthippus dorsatus. By following the color development of individuals from hatching to adulthood, we found that color morph differences begin to develop during the second nymphal stage, are clearly defined by the third nymphal stage, and remain stable throughout the life of an individual. Interestingly, we also observed that shed skins of late nymphal stages are identifiable by color morphs based on their yellowish coloration, rather than the green that marks green body parts. Furthermore, by assessing how these colors are perceived by different visual systems, we found that certain potential predators can chromatically discriminate between morphs, while others may not. These results suggest that the putative genes controlling color morph are active during the early stages of ontogeny, and that green color is likely composed of two components, one present in the cuticle and one not. In addition, the effectiveness of camouflage appears to vary depending on the specific predator involved.

Clones of Myzus persicae were identified by the body colour and esterase differences, and its field populations on various host plants were analyzed into forms. One hundred and fifty-three clones were sampled from the field populations on peach, cabbage, radish, spinach, potato, tobacco, etc. at 3 localities in Japan and electrophoretically examined for their esterase activity at 5 polymorphic esterase loci. A total of 28 forms with different combinations in the body colour and esterase pattern were actually detected. From the overwintering populations at 3 sites in Kyoto 10 different colour-esterase forms were detected.The red forms detected on potato and tobacco within the same area were completely different from each other in their esterase patterns. One particular form was found with high frequency on a wide range of hosts, excluding at least tobacco, at all localities surveyed (form-16). This form appears to be able to reproduce during the midsummer and persist through the severe winter even under the snow.

This research is a follow-up study by presenting the extent of the expression pattern and the presence of each allele locus that marks the color pattern on the cat's body, to add a reference in making it easier for the cat breeder community to form relatively uniform color patterns in certain crossing periods. This research is a descriptive exploratory case study presented qualitatively. Cat samples were screened based on a minimum age of 1 year, and 30 individuals were collected by road sampling. Observation of sample morphology based on mating pathway, recording of morphological characters (body color, color pattern, and tail length). Data were analyzed using allele frequency calculations for genes (dominant and recessive relationship) and concluded qualitatively. The frequency of the presence of gene loci and their alleles was found as many as 8 gene loci, namely: w-W; A A; B-b; C_cb_cs_ca_c; Ta_T_tb; D-d; s-S; OO-oo-Oo; and M-m, and no D-d and I-i gene loci were found. It was concluded that the observed gene locus expression of the Angora crossbreed cat had a variety of random allele frequencies, and did not indicate any particular allele dominance.

Colour vision and colour signals are important to aquatic animals, but light scattering and absorption by water distorts spectral stimuli. To investigate the performance of colour vision in water, and to suggest how photoreceptor spectral sensitivities and body colours might evolve for visual communication, we model the effects of changes in viewing distance and depth on the appearance of fish colours for three teleosts: a barracuda, Sphyraena helleri, which is dichromatic and two damselfishes, Chromis verater and Chromis hanui, which are trichromatic. We assume that photoreceptors light-adapt to the background, thereby implementing the von Kries transformation, which can largely account for observed colour constancy in humans and other animals, including fish. This transformation does not, however, compensate for light scattering over variable viewing distances, which in less than a metre seriously impairs dichromatic colour vision, and makes judgement of colour saturation unreliable for trichromats. The von Kries transformation does substantially offset colour shifts caused by changing depth, so that from depths of 0 to 30 m modelled colour changes (i.e. failures of colour constancy) are sometimes negligible. However, the magnitudes and directions of remaining changes are complex, depending upon the specific spectral sensitivities of the receptors and the reflectance spectra. This predicts that when judgement of colour is important, the spectra of signalling colours and photoreceptor spectral sensitivities should be evolutionarily linked, with the colours dependent on photoreceptor spectral sensitivities, and vice versa.

Intrasexual selection on body coloration is thought to play an important role in the evolution of colour polymorphism, but its physiological underpinnings have received limited attention. In the colour polymorphic cichlid Neochromis omnicaeruleus, three fully sympatric female colour morphs—a plain morph (P) and two conspicuously coloured blotched morphs, black-and-white blotched (WB) and orange blotched (OB)—differ in agonistic behaviour. We compared routine metabolic rate (when females were housed in social isolation), short-term energetic costs of interacting with a same-colour rival housed in an adjacent transparent chamber and oxidative stress between the three female colour morphs. WB females had a lower routine metabolic rate compared with the other colour morphs. WB females also had a lower active metabolic rate during inter-female interactions than OB females, while OB females used more oxygen per unit aggressive act than the other two colour morphs. However, there were no consistent differences in oxidative stress between the three morphs. Concerted divergence in colour, behaviour and metabolism might contribute to the evolution of these polymorphisms in sympatry.

Treating color patterns in a geometric morphometrics framework reveals rapid rates of color evolution that are explained by a combination of intrinsic organismal features (color variation among patches) and geography within a cosmopolitan radiation of birds.

Mimicry with warning colors includes Batesian and Müllerian mimicries. If we divide mimicry by sex, there are theoretically four types of mimicry: unimodal, female‐limited, male‐limited and dual mimicry. The latter three cases cause sexual dimorphism in body color and marking pattern but are rarely reported. In this study, we show that the tussock moth Numenes albofascia is possibly a dual mimic. The wing color and marking pattern of male and female N. albofascia are completely different, with the male's pattern resembling that of the smoky moth Pidorus atratus, while the female pattern resembles that of the tiger moth Arctia caja. Body size also differs greatly between the sexes of N. albofascia, matching the mimicry model species of each sex. These moths are distributed sympatrically in Japan, and their adult seasons overlap with each other. According to lizard feeding experiments, N. albofascia is palatable, while both male and female model species are unpalatable. Actograms in the laboratory and the light trapping in the field suggest that females of N. albofascia fly actively from sunset to midnight, while males fly during the twilight period around dawn. Therefore, male and female N. albofascia might be Batesian mimics of diurnally active P. atratus and nocturnally active A. caja, respectively, and the great sexual dimorphism of this moth could be caused by dual mimicry.

Specimens of Crotalus lepidus klauberi collected in the southwestern United States and northern Mexico have exhibited sexual color dimorphism. The basic body color is green for males and gray for females with both sexes possessing black or dark brown crossbands. This dichromatism has probably evolved for background color-matching through natural selection influenced by predator pressure. The sexual basis of the dimorphism in body color may be the result of a sex-limited character that acts to balance the percentage of color morphs in the population or it may function in intraspecific sex recognition if C. I. klauberi, a diurnally active snake, has redeveloped color vision. Boulenger (1913:233) described sexual color polymorphism for Vipera berus stating that this characteristic was contrary to the rule for snakes. Noble (1937:687, 688) commented that sexual color differences are rare among snakes but noted that V. berus, V. aspis and Coronella are sexually dichromic. Angel (1950:240) cited the occurrence of sexual dichromatism in five species of snakes in the eastern hemisphere: Ablabes baliodirus, Psammodynastes pulverulentus, Trimeresurus puniceus, V. aspis and V. berus. Werler and Smith (1952:570) described sexual dichromatism in Manolepis putnami, heretofore the only snake in the western hemisphere accurately reported to exhibit this character. Crotalus horridus has been reported to generally display sexual dimorphism in body color (Klauber, 1956:656-657), but Schaefer (1969) has shown that the color phases of C. horridus are independent of sex. This paper describes sexual color dimorphism in Crotalus lepidus klauberi Gloyd. Wright and Wright (1957:970-971) first noted color differences between a male and female C. I. klauberi. Specimens of C. I. klauberi (15 males, 11 females) collected from the following geographic areas and examined by us in life have exhibited sexual dimorphism in body coloration: New Mexico (10), Chihuahua (15) and Sonora (1). The collecting localities (Fig. 1) for our specimens encompass a large portion of the northern part of the range of C. I. klauberi (Klauber, 1956; Conant, 1975). We did not have the opportunity to examine material from the southern or extreme western portions of the range, but four specimens from Arizona have been reported to exhibit sexual dichromatism consistent with our observations (Wright and Wright, 1957; J. W. Vincent, pers. comm.). Apparently C. I. lepidus, C. I. maculosus and C. /. morulus normally do not exhibit this character, but it does occur in some populations of C. I. lepidus X klauberi (H. S. Harris, Jr., pers. comm.). Sex was determined by the presence or absence of hemipenes, caudal scale counts and relative tail length measurements. These counts and measurements (Table 1) are consistent with data published by Gloyd (1940:113) and Klauber (1956:124) for sexual size and scutellation dimorphism in C. I. klauberi. Dichromatism occurs only in the dorsal body coloration between the distinct dark crossbands which are either black or dark brown in both sexes. The basic body coloration is green for males and gray for females (PI. 1). There are slight variations (i.e., bluish-green, bluish-gray and pinkish-gray) from these basic colors with juveniles of both sexes generally

1. Fruit flies in the genus Rhagoletis are a model for ecological speciation via sympatric host plant shifting. Rhagoletis mate on or near the fruit of their respective host plants, generating premating reproductive isolation between taxa specialised on different hosts. However, non‐host‐related premating isolation has been observed between some Rhagoletis species associated with morphological differences in body colour and wing patterns. 2. Here, the extent of epicuticular hydrocarbon (CHC) variation as a possible, additional determinant of mate choice in adults of six Rhagoletis taxa, including the apple and hawthorn‐infesting host races of R. pomonella is investigated. 3. Gas‐chromatography‐mass‐spectrometry revealed 36 repeatable and quantifiable hydrocarbon components present on the epicuticles of all six fly taxa, comprised of at least 53 different CHC compounds, with chain lengths varying from 27 to 34 carbon atoms, consisting of n‐alkanes, mono‐, dimethyl‐, and trimethyl‐alkanes, alkenes, and alkadienes. There were significant differences in the relative proportions of CHCs between adult R. cingulata , R. cornivora , R. zephyria , R. mendax , and R. pomonella , as well as between the apple‐ and hawthorn‐infesting host races of R. pomonella . Furthermore, within the R. pomonella host races and R. mendax , significant CHC differences were observed between the sexes and across collecting sites. 4. The results are consistent with variation in CHCs potentially contributing to observed patterns of premating isolation between Rhagoletis taxa, possibly due to combination of sexual and host‐related selection, which will necessitate further, in depth chemical analyses and future mating trials to substantiate.

Inconspicuous genetic and morphological patterns challenge the taxonomic status of endemic species Bodianus insularis (Labridae)

Shell characters (e.g. colour, banding pattern, size, shape) are commonly used to discriminate among closely related gastropod species. However, in slugs the shell is internal, often reduced and taxonomically uninformative. Therefore, body colour pattern and the size and shape of the (proximal) genitalia are the most important taxonomic markers in slugs. However, body colour and the development of stylommatophoran reproductive organs is subject to considerable intraspecific, seasonal and physiological variation. The identification of immature slugs is therefore often especially problematic. Two biological species of land slugs of the arionid subgenus Mesarion, viz. Arion subfuscus (Draparnaud, 1805) and A. fuscus (Muller, 1774), are very similar morphologically and have overlapping distributional ranges in northwestern Europe. Using allozyme data and gonad morphology, both species can be consistently delineated, even in sympatry. Arion fuscus is widespread throughout Central, North and East Europe, whereas A. subfuscus is restricted to West Europe. DNA sequence variation in nuclear (ITS-1) and mitochondrial (16S rDNA) genes revealed two major evolutionary lineages in A. fuscus, one in the Balkan region and another in the Alps and the rest of Europe, and five evolutionary lineages (S1-S5) with largely allopatric distributions in A. subfuscus. Two of the A. subfuscus lineages (S1 and S2) have overlapping distributions and may hybridize. Both allozyme electrophoresis and DNA sequencing have a number of disadvantages. Allozyme data can only be used when fresh or deep-frozen tissue is available. Although electrophoretic zymograms afford excellent markers for distinguishing A. subfuscus from A. fuscus, they do not allow accurate discrimination of the evolutionary lineages. The sequencing of DNA requires PCR-amplification using specific primers, followed by purification of the PCR product and sequencing of the amplified region. This procedure is often expensive and time-consuming. Hence, when large numbers of (immature) individuals have to be analysed, a rapid technique allowing reliable identifications of the cryptic species and lineages within the A. subfuscus/fuscus complex is needed. Here we present an easy and convenient molecular marker based on a restriction-fragment length digestion of a PCR-amplified 16S rDNA stretch (PCR-RFLP), which allows practical and reliable identification of the northwestern European evolutionary lineages within the A. subfuscus/fuscus complex. In the period February–May 2004, a total of 175 A. subfuscus/ fuscus individuals of different life-stages were collected in 25 Belgian and one German locality. A list of the localities and the number of individuals sampled per locality are available upon request. Individuals were frozen at 2808C. All specimens were identified by sequencing of the mitochondrial 16S rDNA and, whenever enough digestive gland tissue was available, using allozyme analysis. DNA sequencing was also used to assign all individuals to one of the evolutionary lineages. Then, a portion of foot tissue of each individual was digested for 2–5 h at 608C in 200 ml Taq DNA polymerase 10 buffer to which proteinase K was added. Afterwards, the unpurified samples were heated to 958C for 5 min. A part of the 16S rDNA gene was amplified with primers 16SAR (50CGCCTGTTTAWCAAAAACAT-30) and 16SBR (50CCGGTYTGAACTCAGATCAGATCAYGT-30) under the following conditions: 3 min at 978C, then 30 cycles of 45 s at 958C, 45 s at 468C and 1 min at 728C, and ending with 5 min at 728C. PCR reaction volumes contained 50 mM KCl, 10 mM Tris–HCl (pH 9.0 at 258C), 1% Triton X-100 (Promega), 5 mM 16SAR primer, 15 mM 16SBR primer, 200 mM of each dNTP, 1.75 units of Taq DNA polymerase (Promega), 1.5 mMMgCl2 and 1 ml of template DNA. Suitable restriction sites and enzymes were searched inWebcutter v.2.0. Two promising target enzymes (i.e. Ssp I an Mum I) were retained for further analysis. The amplification PCR products were digested with the two restriction enzymes (MBI Fermentas) as follows: 1.1 ml Gþ buffer [10 mM Tris–HCl (pH 7.5), 10 mM MgCl2, 50 mM NaCl and 0.1 mg/ml BSA], 0.1 ml Ssp I enzyme (10 units/1 ml) and 0.1 ml Mum I enzyme (10 units/1 ml) were added to 5 ml of PCR product and kept for 12 h at 378C. Then, the samples were kept at 658C for 20 min and afterwards stored at 48C. Restriction products were run on an ethidium bromide 3% agarose gel for 30 min at 125 V and photographed under ultraviolet light. Four taxa were found in the 26 populations: A. fuscus, A. subfuscus S1, S2 and S3. The number and the size of DNA fragments obtained after PCR-RFLP for each of these northwestern European taxa of the A. subfuscus/fuscus complex are summarized in Table 1. PCR-RFLP analysis of the 16S rDNA allowed unambiguous discrimination among the four taxa (Table 1, Fig. 1). The differences in sizes between the PCRamplified fragments and the fragments obtained after digestion are due to the presence of a restriction site in all taxa, and of a second restriction site in A. subfuscus S2 and S3. Arion fuscus showed one restriction site for Ssp I that yielded two fragments of approximately 435 bp and 30 bp. Arion subfuscus S1 also had one restriction site for Ssp I that resulted in two fragments of approximately 250 bp and 200 bp. Both A. subfuscus S2 and S3 had one restriction site for Ssp I and one for Mum I resulting in three fragments of approximately 285 bp, 160 bp and 30 bp in A. subfuscus S2 and 305 bp, 100 bp and 30 bp in A. subfuscus S3.

A comparative morphological analysis has been conducted for antlered sculpins of the genus Enophrys from three remote regions: the Sea of Japan, the Sea of Okhotsk, and the Bering Sea. Variations in their body color pattern and also meristic and measurable characters have been analyzed. As the analysis has shown, antlered sculpins from the Sea of Japan differ significantly from the two other samples in the body color, some head proportions, and size and location of the fins D1, D2, A, V, and P. Differences on the subspecies level (CD 1.28) have been found for five of the characters studied and a hiatus (differences on the species level) for one character (depth of D1). The data obtained confirm the previously published assumption that the fish from the Sea of Japan possibly belong to the species E. namiyei.

Body size and colour morphs are important life-history traits, and various factors are responsible for intraspecific variation in ladybirds. However, little is known regarding their dynamics in the field populations. To address the tripartite relationship among colour morphs, body size, and adult age, the following three surveys were conducted: First, morph-type (dark and light colour) frequencies were compared between generations and adult age (teneral and post-teneral) in a population in Osaka, Japan. Second, body size was examined by generation, morph type, adult age and sex. Third, body size was compared among morph types based on specimen surveys. The results demonstrated that the post-teneral frequency of dark morphs was significantly higher than that of tenerals in the spring and autumn generations of both sexes. The mean body size of the dark morphs was significantly smaller than that of the light morphs of both sexes in the autumn generation, and there was a similar tendency in the spring generation. The specimen survey also revealed that dark morphs were smaller than light post-teneral morphs. These results suggest that the mortality of the light morphs may be higher than that of the dark morphs during spring and autumn. Therefore, smaller light morph individuals are likely to have shorter longevity. Considering that smaller dark morphs may be able to survive owing to the advantages of solar radiation, the mean body size of dark morphs may be smaller than that of light morphs.