The modelling of avian visual perception predicts behavioural rejection responses to foreign egg colours

How do birds tell the colours of their own and foreign eggs apart? We demonstrate that perceptual modelling of avian visual discrimination can predict behavioural rejection responses to foreign eggs in the nest of wild birds. We use a photoreceptor noise-limited colour opponent model of visual perception to evaluate its accuracy as a predictor of behavioural rates of experimental egg discrimination in the song thrush Turdus philomelos. The visual modelling of experimental and natural eggshell colours suggests that photon capture from the ultraviolet and short wavelength-sensitive cones elicits egg rejection decisions in song thrushes, while inter-clutch variation of egg coloration provides sufficient contrasts for detecting conspecific parasitism in this species. Biologically realistic sensory models provide an important tool for relating variability of behavioural responses to perceived phenotypic variation.     

The cryptic responses of hatchery-reared sole to a natural sand substratum

In laboratory experiments, both reared and wild sole Solea solea selected a sand substratum in preference to a hard substratum. Reared sole with no previous experience of sand buried quickly when placed on sand. Light motivated burial, and the motivation of reared sole to bury was as strong as that of wild sole. The burial efficiency (the proportion of the ocular side covered by sand after a single burial attempt) of reared sole was lower than that of wild sole, but increased to that of wild sole after a period of 12 days maintenance on sand. Motivation to bury is therefore innate, but efficiency is affected by experience. The reactive distance of reared sole to a standardized predation threat was the same as that of wild sole and was shorter when buried (6 cm) than when not buried (15 cm). Burial therefore affected the response to a predation threat, indicating that burial is a cryptic behaviour. Munsell colour charts were used to determine the time required for reared sole to match the skin colour 'tone' of wild sole after placement on sand. Adaptation of colour value (lightness) took 4–7 days, but adaptation of chroma (intensity of colour) and hue took 33 and 69 days respectively. It is therefore recommended that flatfishes reared for stock enhancement exercises are conditioned to sand prior to release due to the relatively long time required for crypsis to improve through colour adaptation and burying.     

Latitudinal variation of morphological characteristics in the swallowtail Sericinus montelus Gray, 1798 (Lepidoptera: Papilionidae)

Patterns of latitudinal variation in the phenotype or genotype of an organism may provide evidence for natural selection. In this study, we investigated seven populations of swallowtail Sericinus montelus Gray, 1798 (Lepidoptera: Papilionidae), a non‐migratory species, to explore the latitudinal variation of morphological characteristics in adults. The results showed that body size and the development of dark pigmentation on wings in this species responded strongly to latitude. The body size of both male and female adult of S. montelus was negatively correlated with latitude. These findings provided solid evidence to support the converse Bergmann's rule. We considered that the observed variation in morphological characteristics was most likely mediated by the seasonal length and thermoperiod to adapt to different latitudinal environment (e.g. shortened developmental time of immature stages for smaller body size at higher latitude). Moreover, the tendency towards progressively darker colour patterns (only in adult males) at increasingly low latitudes was consistent with Gloger's rule. We suggested that the observed colour variation was most likely associated with thermoregulation. Slight variation in the morphology of the W‐shaped stripe on the forewing of adult females was also found, and we presumed that the functions of sexual preferences, mimicry and thermoregulation might be involved.     

Cephalopod dynamic camouflage: bridging the continuum between background matching and disruptive coloration

Individual cuttlefish, octopus and squid have the versatile capability to use body patterns for background matching and disruptive coloration. We define—qualitatively and quantitatively—the chief characteristics of the three major body pattern types used for camouflage by cephalopods: uniform and mottle patterns for background matching, and disruptive patterns that primarily enhance disruptiveness but aid background matching as well. There is great variation within each of the three body pattern types, but by defining their chief characteristics we lay the groundwork to test camouflage concepts by correlating background statistics with those of the body pattern. We describe at least three ways in which background matching can be achieved in cephalopods. Disruptive patterns in cuttlefish possess all four of the basic components of ‘disruptiveness’, supporting Cott''s hypotheses, and we provide field examples of disruptive coloration in which the body pattern contrast exceeds that of the immediate surrounds. Based upon laboratory testing as well as thousands of images of camouflaged cephalopods in the field (a sample is provided on a web archive), we note that size, contrast and edges of background objects are key visual cues that guide cephalopod camouflage patterning. Mottle and disruptive patterns are frequently mixed, suggesting that background matching and disruptive mechanisms are often used in the same pattern.     

Attractiveness of various colours to Australian tephritid fruit flies in the field

The response of tephritid fruit flies to variously coloured sticky traps was studied in the field in southeastern Queensland over three seasons (1978–81). Three species, Dacus tryoni (Froggatt), D. neohumeralis Hardy and D. cacuminatus (Hering), made up the majority of the flies captured. On a per unit area basis, a sticky flat trap was more efficient than a sticky wing trap and was adopted as the trap design. Daylight fluorescent (DF) Saturn Yellow captured significantly more flies than any of the other ten colours, or perspex and aluminium foil, tested, although the DF colours Lime, Blaze Orange and Emerald were also attractive. There was a significant correlation between the number of flies captured by a colour and the difference, in nanometres, between the peak reflected wavelength of the colour and 550 nm which is quoted as the peak wavelength reflected by green leaves. The three species did not differ in their responses to the coloured traps, and more males than females were captured. When either cuelure or methyl eugenol was added to the sticky traps no one colour emerged as significantly superior, but the yellow, and yellow/green DF colours consistently caught more flies. The attractiveness of coloured traps declined as the number of flies captured increased. The efficiency of Steiner and McPhail traps was not increased by the addition of any attractive colour. Of various possible trap shapes of equivalent surface area, circular and square traps captured more flies than did triangular, rectangular and diamond shaped traps. When spheres were tested, those of 10 cm diameter captured more flies than those of 5 cm diameter, and more flies were caught on black, than on yellow or green spheres.

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Résumé Plusieurs espèces de téphritidées, principalement Dacus tryoni, D. neohumeralis et D. cacuminatus, ont été capturées avec des pièges gluants colorés dans le S.E. Queensland (Australie) pendant 3 saisons (1978–81). Des pièges plats de 15×20 cm ont capturé plus de mouches/cm² que des pièges ailés formés par 2 plans à 90°. Les couleurs jaune-vert ont été préferées par les 3 espèces, le jaune saturne lumière du jour fluorescent ayant été le plus attractif. Une corrélation significative a été trouvée entre le nombre de mouches capturées par une couleur et la différence en nanomètres entre le mode des longueurs d'onde reflétées par cette couleur et 550 nm considéré généralement comme le mode des longueurs d'onde reflétées par les feuilles vertes. Les 3 espèces ont montré les mêmes réponses aux pièges colorés et le nombre de mâles avait tendance à excéder celui des femelles. Quand de la cuelure ou du méthyl eugénol étaient ajoutés aux pièges gluants, aucune couleur n'était significativement supérieure, mais les couleurs fluorescentes lumière du jour jaune et jaune-vert ont capturé nettement plus de mouches que le bleu, l'orange, le rouge, le noir, le blanc, la feuille d'aluminium ou le perspex clair. Le taux de capture diminuait plus le nombre de mouches sur le piège augmentait. Ceci peut expliquer la diminution apparente de la discrimination entre les couleurs quand des leurres mâles sont posés sur les pièges. Des expériences avec des pièges tachetés et un retrait quotidien des mouches ont montré que la diminution d'attractivité était une réponse à un stimulus visuel. Après plusieurs jours d'exposition, un piège de couleur relativement peu attractive, capturant des mouches à un taux faible mais appréciable, a capturé un nombre de mouches voisin de celui d'un piège de couleur attractive qui avait commencé par capturer un grand nombre de mouches, mais avait vu baisser son attractivité par suite de la présence des mouches captives. Les données hebdomadaires sur les captures n'ont pas présenté de différences suivant les couleurs, mais la sommation des captures quotidiennes (avec retrait quotidien des mouches) sur la même période a montré des différences d'attractivité significatives.Les pièges de Steiner et de McPhail n'ont présenté aucun taux de capture différent quand ils étaient peints sur les 2/3 inférieurs avec des couleurs attractives jaune-vert.Des sphères noires ont capturé plus de mouches que des sphères rouges, jaunes ou vertes, et des sphères de 10 cm de diamètre étaient plus attractives que celles de 5 cm.Quand un choix de pièges plats de la même couleur et de la même surface mais de formes diverses a été proposé aux mouches, les pièges circulaires et carrés ont capturé plus de mouches que les pièges triangulaires, rectangulaires ou rhombiques.

     

Distinctive convergence in Australian floral colours seen through the eyes of Australian birds

We used a colour-space model of avian vision to assess whether a distinctive bird pollination syndrome exists for floral colour among Australian angiosperms. We also used a novel phylogenetically based method to assess whether such a syndrome represents a significant degree of convergent evolution. About half of the 80 species in our sample that attract nectarivorous birds had floral colours in a small, isolated region of colour space characterized by an emphasis on long-wavelength reflection. The distinctiveness of this ‘red arm’ region was much greater when colours were modelled for violet-sensitive (VS) avian vision than for the ultraviolet-sensitive visual system. Honeyeaters (Meliphagidae) are the dominant avian nectarivores in Australia and have VS vision. Ancestral state reconstructions suggest that 31 lineages evolved into the red arm region, whereas simulations indicate that an average of five or six lineages and a maximum of 22 are likely to have entered in the absence of selection. Thus, significant evolutionary convergence on a distinctive floral colour syndrome for bird pollination has occurred in Australia, although only a subset of bird-pollinated taxa belongs to this syndrome. The visual system of honeyeaters has been the apparent driver of this convergence.     

Ultraviolet and carotenoid‐based coloration in the viviparous lizard Zootoca vivipara (Squamata: Lacertidae) in relation to age,sex, and morphology

Lizards display structural and pigment‐based colorations, and their visual system is sensitive to wavelengths of 300–700 nm. However, few studies in squamate reptiles have quantified interindividual colour variation that includes the structural ultraviolet (UV) component (300–400 nm). In the present study, we investigated variability of a ventral UV/yellow–red ornamentation in the common lizard Zootoca vivipara, including an analysis of spatial distribution, as well as sex and age differences. We also investigated whether the expression of coloration is related to body size and condition. Our analyses revealed two distinct patches: a gular patch with a strong UV reflectance and a belly patch with a dominant yellow–red reflectance. Males displayed a less saturated throat coloration with higher UV chroma and UV hue, and had a redder but duller belly coloration than females. Yearlings had less elaborate ornaments than adults, although they already displayed a yellow–red sexual dichromatism on the belly. UV sexual dichromatism was only apparent in adults as a result of a weaker UV reflectance in females, suggesting potential fitness costs of a bright UV coloration in that sex. Different colour traits were related to body size in both sexes, as well as to body condition in males. We discuss the potential evolutionary scenarios leading to the maintenance of this ornament in common lizards. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 128–141.     

The Fugu tyrp1 promoter directs specific GFP expression in zebrafish: tools to study the RPE and the neural crest‐derived melanophores

In vertebrates, pigment cells account for a small percentage of the total cell population and they intermingle with other cell types. This makes it difficult to isolate them for analyzes of their functions in the context of development. To alleviate such difficulty, we generated two stable transgenic zebrafish lines (pt101 and pt102) that express green fluorescent protein (GFP) in melanophores under the control of the 1 kb Fugu tyrp1 promoter. In pt101, GFP is expressed in both retinal pigment epithelium (RPE) cells and the neural crest‐derived melanophores (NCDM), whereas in pt102, GFP is predominately expressed in the NCDM. Our results indicate that the Fugu tyrp1 promoter can direct transgene expression in a cell‐type‐specific manner in zebrafish. In addition, our findings provide evidence supporting differential regulations of melanin‐synthesizing genes in RPE cells and the NCDM in zebrafish. Utilizing the varying GFP expression levels in these fish, we have isolated melanophores via flow cytometry and revealed the capability of sorting the NCDM from RPE cells as well. Thus, these transgenic lines are useful tools to study melanophores in zebrafish.     

Development and evolution of melanophore patterns in fishes of the genus Danio (Teleostei: Cyprinidae)

Pigmentation patterns in vertebrates have become an important model for those interested in mechanisms of pattern determination. I present detailed information on the development of melanophore patterns in the zebrafish, Danio rerio, five close relatives of that species, and an outgroup. The comparison of the ontogeny of melanophore patterns in this group is an important first step towards understanding the developmental basis of the interspecific variation. Pigment patterns in this group range from no distinct patterning at all to stripes of differing numbers and widths to reticulated stripes. Species examined form identical larval patterns and follow a common sequence of events from which different elements are eliminated or altered to produce the variety of patterns seen in the group. As flexion is completed, melanophores move from larval positions onto the flanks of the fish. In D. rerio, D. rerio ‘leo,’ D. kerri, and D. malabaricus, xanthophores become established on the body of the fish as the melanophores move; erythrophores become established on the flanks of D. albolineatus and D. sp. cf. aequipinnatus. An increase in melanophore number, begun at this time, continues at a higher rate in D. rerio, D. kerri, D. sp. cf. aequipinnatus and Tanichthys albonubes than in the other three species. This results in a greater number of melanophores on adults in those species with a higher rate of melanophore increase. No distinct pattern forms, except on the caudal peduncle, in D. albolineatus. In all other Danio species, melanophore stripes form first below then above the horizontal myoseptum. Additional stripes are added first below then above these initial two stripes. D. kerri develops fewer, wider melanophore stripes than D. rerio. After initial stripe formation, D. malabaricus and D. sp. cf. aequipinnatus both developed vertical pattern elements and reticulations in the melanophore pattern. Differences in patterns between species are similar in several cases to described mutants of the zebrafish, suggesting that some aspects of interspecific pigmentation pattern variation may be under relatively simple genetic control. J. Morphol. 241:83–105, 1999. © 1999 Wiley‐Liss, Inc.     

The contribution of structural-, psittacofulvin- and melanin-based colouration to sexual dichromatism in Australasian parrots

Colour ornamentation in animals is exceptionally diverse, but some colours may provide better signals of individual quality or more efficient visual stimuli and, thus, be more often used as sexual signals. This may depend on physiological costs, which depend on the mechanism of colour production (e.g. exogenously acquired colouration in passerine birds appears to be most sexually dichromatic). We studied sexual dichromatism in a sample of 27 Australasian parrot species with pigment- (melanin and psittacofulvin) and structural-based colouration, to test whether some of these types of colouration are more prominent in sexual ornamentation. Unlike passerines, in which long wavelength colouration (yellow to red) usually involves exogenous and costly carotenoid pigments, yellow to red colouration in parrots is based on endogenously synthesized psittacofulvin pigments. This allows us to assess whether costly exogenous pigments are necessary for these plumage colours to have a prominent role in sexual signalling. Structural blue colouration showed the largest and most consistent sexual dichromatism, both in area and perceptually relevant chromatic differences, indicating that it is often ornamental in parrots. By contrast, we found little evidence for consistent sexual dichromatism in melanin-based colouration. Unlike passerines, yellow to red colouration was not strongly sexually dichromatic: although the area of colouration was generally larger in males, colour differences between the sexes were on average imperceptible to parrots. This is consistent with the idea that the prominent yellow to red sexual dichromatism in passerines is related to the use of carotenoid pigments, rather than resulting from sensory bias for these colours.     

Viability of brown trout embryos positively linked to melanin-based but negatively to carotenoid-based colours of their fathers

'Good-genes' models of sexual selection predict significant additive genetic variation for fitness-correlated traits within populations to be revealed by phenotypic traits. To test this prediction, we sampled brown trout (Salmo trutta) from their natural spawning place, analysed their carotenoid-based red and melanin-based dark skin colours and tested whether these colours can be used to predict offspring viability. We produced half-sib families by in vitro fertilization, reared the resulting embryos under standardized conditions, released the hatchlings into a streamlet and identified the surviving juveniles 20 months later with microsatellite markers. Embryo viability was revealed by the sires' dark pigmentation: darker males sired more viable offspring. However, the sires' red coloration correlated negatively with embryo survival. Our study demonstrates that genetic variation for fitness-correlated traits is revealed by male colour traits in our study population, but contrary to predictions from other studies, intense red colours do not signal good genes.     

颜色对梨小食心虫产卵选择性的影响

梨小食心虫(Grapholitha molesta Busck)是一种重要的果树害虫,早春产卵喜在桃嫩梢叶上,为探明寄主颜色在其产卵选择中的作用,利用彩色卡纸模拟寄主颜色,室内比较了红、粉红、浅粉、橙黄、深黄、浅黄、青绿、深绿、浅绿、蓝、紫、褐色等12种不同颜色基质对其成虫产卵选择性的影响。结果发现:基质颜色对梨小食心虫的产卵选择性有显著影响,其产卵偏嗜浅黄和浅绿色,白色和黑色参比时其产卵选择率分别依次为68.9%、63.8%和64.1%、65.5%,蓝和浅粉色则表现一定的拒避作用,白色和黑色参比时其产卵选择率分别依次为47.7%、40.4%和47.2%、42.7%,且参比色对其产卵选择性影响差异显著。基质颜色对其产卵量亦有显著性影响,无论黑或白色参比,黄、绿颜色上的产卵量均较多,尤其是深黄、深绿和青绿色。基质颜色对1—7日龄梨小食心虫成虫的产卵选择性均有显著影响。白色参比时,2、3日龄蛾对浅绿和浅黄色的产卵选择率显著高于其他颜色;黑色参比时,2日龄时明显偏嗜浅绿色(79.7%),6日龄时明显偏嗜浅黄色(74.8%)。表明寄主颜色在梨小食心虫产卵场所选择中具有重要作用,为其卵期监测和防控中颜色应用乃至进一步揭示其产卵寄主选择机理提供了依据和参考。     

The cream dilution gene, responsible for the palomino and buckskin coat colours, maps to horse chromosome 21

The colour locus historically referred to as C in the horse is linked to microsatellites markers on horse chromosome 21. Preliminary results demonstrated linkage of Ccr, thought to be the cream dilution variant of the C locus, to HTG10. An analysis of horse chromosome 21 using additional families confirmed and established a group of markers linked to Ccr. This work also improved the resolution of previously reported linkage maps for this chromosome. Linkage analysis unambiguously produced the map order: SGCV16-(19.1 cM)-HTG10-(3.8 cM)-LEX60/COR73-(1.3 cM)-COR68-(4.5 cM)- Ccr-(11.9 cM)-LEX31. Comparative and synteny data suggested that the horse C locus is not tyrosinase (TYR).     

A novel transgenic line using the Cre–lox system to allow permanent lineage‐labeling of the zebrafish neural crest

Accurate lineage tracing is crucial to understanding of developmental and stem cell biology, but is particularly challenging for transient and highly dispersive cell‐types like the neural crest (NC). The authors report in this article a new zebrafish transgenic line Tg(‐4725sox10:Cre)^ba74. This line expresses Cre under the control of a well‐characterized portion of the sox10 promoter and, by crossing to a floxed‐reporter line, the authors show in this article that expression in this line is consistent with those described for GFP reporter lines using the same promoter. Reporter expression is readily detected in patterns consistent with the early expression domains. Thus, the authors see all major groups (pigment, neural, and skeletal) of NC‐derived cell‐types, as well as cell‐types derived from the known non‐NC sites of sox10 expression, including otic epithelium and oligodendrocytes. This line provides an invaluable tool for the further study of zebrafish NC development and NC‐derived stem cells as well as that of the otic vesicle and oligodendrocytes. genesis 50:750–757, 2012. © 2012 Wiley Periodicals, Inc.     

Diverse responses of root cell structure to aluminium stress

Plant cells respond to a certain stress factor in different ways depending on their developmental stage and type of tissue. Structural damage may be severe or even lethal in individual cells within a tissue that exhibits moderate or no effects of stress. In the case of aluminium toxicity, detailed observations of root tips of 3 day old Zea mays L., cv. TO360 seedlings revealed differences in the response of some cells. Two different structural changes appeared within root epidermis just behind the root cap. Cells with dark and shrunken cytoplasm occurred next to swollen cells with preserved cellular compartments. Within the root cortex, individual cells or a few cells of a file have severely damaged cytoplasm, in contrast to almost undisturbed cytoplasm of adjacent cells. Such extremely sensitive cells appear irregularly within the root apex. Their structural similarity with cells that are observed after a hypersensitive response in infected plant tissues suggests a role to accumulate aluminium, in order to allow the surrounding tissue to survive the stress.     

Differences in biological and behavioural characteristics of Harmonia axyridis (Coleoptera: Coccinellidae) according to colour patterns of elytra

Samples of overwintering populations of Harmonia axyridis were classified into five colour patterns, succinea 1, succinea 2, conspicua, spectabilis and axyridis. Generally, the succinea 1 colour pattern was dominant at six collecting sites in Daejon and Chungnam provinces of Korea and their occurrence proportion was over 50%. Non‐melanic forms such as succinea 1 and 2 were noted in about 90% of collected individuals. On the other hand, conspicua and spectabilis as melanic forms were dominant in the laboratory. One hypothesis is that the difference between field and laboratory populations is related to non‐random mating and environmental conditions. Practically, in mate‐choice experiments, most colour pattern ladybirds seemed to mate with the melanic form, especially the conspicua form. The body size (length) of H. axyridis in colour patterns was slightly different, but in females, there was no significant difference among colour patterns. However, both lengths of males were significantly different among colour patterns. In reproductive ability (fecundity), there was no difference among colour patterns.     

Behavioural responses of the yellow emitting annelid Tomopteris helgolandica to photic stimuli

In contrast to most mesopelagic bioluminescent organisms specialised in the emission and reception of blue light, the planktonic annelid Tomopteris helgolandica produces yellow light. This unusual feature has long been suggested to serve for intraspecific communication. Yet, this virtually admitted hypothesis has never been tested. In this behavioural study of spectral colour sensitivity, we first present an illustrated repertoire of the postures and action patterns described by captive specimens. Then video tracking and motion analysis are used to quantify the behavioural responses of singled out worms to photic stimuli imitating intraspecific (yellow) or interspecific (blue) bioluminescent signals. We show the ability of T. helgolandica to react and to contrast its responses to bioluminescent‐like blue and yellow light signals. In particular, the attractive effect of yellow light and the variation of angular velocity observed according to the pattern of yellow stimuli (flashes versus glows) support the intraspecific communication hypothesis. However, given the behavioural patterns of T. helgolandica, including mechanically induced light emission, the possibility that bioluminescence may be part of escape/defence responses to predation, should remain an open question.     

Cell-type-specific responses to the microbiota across all tissues of the larval zebrafish

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