Is countershading camouflage robust to lighting change due to weather?

Countershading is a pattern of coloration thought to have evolved in order to implement camouflage. By adopting a pattern of coloration that makes the surface facing towards the sun darker and the surface facing away from the sun lighter, the overall amount of light reflected off an animal can be made more uniformly bright. Countershading could hence contribute to visual camouflage by increasing background matching or reducing cues to shape. However, the usefulness of countershading is constrained by a particular pattern delivering ‘optimal’ camouflage only for very specific lighting conditions. In this study, we test the robustness of countershading camouflage to lighting change due to weather, using human participants as a ‘generic’ predator. In a simulated three-dimensional environment, we constructed an array of simple leaf-shaped items and a single ellipsoidal target ‘prey’. We set these items in two light environments: strongly directional ‘sunny’ and more diffuse ‘cloudy’. The target object was given the optimal pattern of countershading for one of these two environment types or displayed a uniform pattern. By measuring detection time and accuracy, we explored whether and how target detection depended on the match between the pattern of coloration on the target object and scene lighting. Detection times were longest when the countershading was appropriate to the illumination; incorrectly camouflaged targets were detected with a similar pattern of speed and accuracy to uniformly coloured targets. We conclude that structural changes in light environment, such as caused by differences in weather, do change the effectiveness of countershading camouflage

Resistance to the attack of Bactrocera oleae (Gmelin) of some Sicilian olive cultivars

Genetic resistance of olive germplasm could be an important tool in the control of Bactrocera oleae (Gmelin), the key pest in the Mediterranean olive growing. Up to now, no study was carried out on olive cultivars stressed a complete resistance to the attack of B. oleae, and few scientific data are available on susceptibility to olive fruit fly of Sicilian cultivars, although differences among susceptibility of cultivars could be usefully considered to obtain quality productions and to reduce insecticides use both in organic and conventional olive growing. The present study was carried out at Castelvetrano (Trapani province, Sicily), in the olive germplasm collection of Ente di Sviluppo Agricolo of the Sicilian Region and Dipartimento di Colture Arboree of the University of Palermo. From 2002 to 2005, infestation levels in drupes of 18 cv, representing the most widely cultivated in Sicily was recorded. Samplings were carried out every 11-20 days, starting from the second half of August to the end of October. Moreover, from 2003 to 2005 infestation levels were correlated with size and hardness of olives, while in 2004-2005 data on olive coloration were collected at different ripening stages. Among the cultivars producing larger olives, Nocellara del Belice resulted the most susceptible to the olive fruit fly attacks, while Nocellara messinese was the less infested one. Among cultivars with medium, small-sized fruits Moresca, Vaddarica, Nasitana frutto grosso, Minuta and Bottone di gallo were the less susceptible ones. Among the tested cultivars Nocellara del Belice was the most attacked one in every year of the research. A positive correlation between infestation and olive size was found, resulting in higher infestation levels on the cultivars producing larger olives. B. oleae showed a clear preference for green drupes, instead of reddish or blackish ones. In two out of three years a negative correlation between hardness and infestation was found in September

Egg-laying substrate selection for optimal camouflage by quail

Camouflage is conferred by background matching and disruption, which are both affected by microhabitat [1]. However, microhabitat selection that enhances camouflage has only been demonstrated in species with discrete phenotypic morphs [2 and 3]. For most animals, phenotypic variation is continuous [4 and 5]; here we explore whether such individuals can select microhabitats to best exploit camouflage. We use substrate selection in a ground-nesting bird (Japanese quail, Coturnix japonica). For such species, threat from visual predators is high [6] and egg appearance shows strong between-female variation [7]. In quail, variation in appearance is particularly obvious in the amount of dark maculation on the light-colored shell [8]. When given a choice, birds consistently selected laying substrates that made visual detection of their egg outline most challenging. However, the strategy for maximizing camouflage varied with the degree of egg maculation. Females laying heavily maculated eggs selected the substrate that more closely matched egg maculation color properties, leading to camouflage through disruptive coloration. For lightly maculated eggs, females chose a substrate that best matched their egg background coloration, suggesting background matching. Our results show that quail “know” their individual egg patterning and seek out a nest position that provides most effective camouflage for their individual phenotyp

Colour change and assortment in the western rainbowfish

Grouping behaviour is widespread across the animal kingdom, and is known to reduce an individual's risk of predation, for example through predator confusion. Theory predicts that individuals that are different in appearance to the rest of the group are at a greater risk of predation because they are more conspicuous to predators (the ‘oddity’ effect). Thus, animals should choose group mates that are the most similar in appearance to themselves. Another common antipredator tactic is crypsis (camouflage). Fishes are capable of changing colour to match their visual background, but few studies have examined how this might influence shoaling decisions, particularly in the context of the oddity effect. We induced colour pattern changes in a colourful species of freshwater fish, the western rainbowfish, Melanotaenia australis, by maintaining fish in dark and pale aquaria for 2 weeks. Analysis of the proportion of black body pigmentation confirmed that rainbowfish in dark environments developed darker colour patterns than those held in pale environments. We then conducted behavioural observations to determine whether fish subsequently based their shoaling decisions on body coloration. We found that rainbowfish preferred to shoal with similar individuals; fish that had been held in dark aquaria preferred to shoal with other dark fish and fish from pale aquaria preferred other pale fish. Our findings are consistent with the predictions of the oddity effect and demonstrate how morphological colour pattern changes and behavioural decisions interact to mediate antipredator tactics in fish

Genetic and morphological differences between Sebastes vulpes and S. zonatus (Teleostei: Scorpaeniformes: Scorpaenidae)

The taxonomic status of Sebastes vulpes and S. zonatus were clarified by comprehensive genetic (amplif ied fragment length polymorphisms [AFLP] and mitochondrial DNA [mtDNA] variation) and morphological analyses on a total of 65 specimens collected from a single locality. A principal coordinate analysis based on 364 AFLP loci separated the specimens completely into two genetically distinct groups that corresponded to S. vulpes and S. zonatus according to body coloration and that indicated that they are reproductively isolated species. Significant morphological differences were also evident between the two groups; 1) separation by principal component analysis based on 31 measurements, and 2)separation according to differences in counts of gill rakers and dorsal-fin spines without basal scales, and in the frequencies of specimens with small scales on the lower jaw. Restriction of gene flow between the two groups was also indicated by the pairwise ΦST values estimated from variations in partial sequences from the mtDNA control region, although the minimum spanning network did not result in separation into distinct clades. The latter was likely due to incomplete lineage sorting between S. vulpes and S. zonatus owing to their recent speciation

Establishing the behavioural limits for countershaded camouflage

Countershading is a ubiquitous patterning of animals whereby the side that typically faces the highest illumination is darker. When tuned to specific lighting conditions and body orientation with respect to the light field, countershading minimizes the gradient of light the body reflects by counterbalancing shadowing due to illumination, and has therefore classically been thought of as an adaptation for visual camouflage. However, whether and how crypsis degrades when body orientation with respect to the light field is non-optimal has never been studied. We tested the behavioural limits on body orientation for countershading to deliver effective visual camouflage. We asked human participants to detect a countershaded target in a simulated three-dimensional environment. The target was optimally coloured for crypsis in a reference orientation and was displayed at different orientations. Search performance dramatically improved for deviations beyond 15 degrees. Detection time was significantly shorter and accuracy significantly higher than when the target orientation matched the countershading pattern. This work demonstrates the importance of maintaining body orientation appropriate for the displayed camouflage pattern, suggesting a possible selective pressure for animals to orient themselves appropriately to enhance crypsis

Biopigment Tracing of Mangrove Rhizophora mucronate Leaf an Bark Waste and Its Application for Batik Dyeing by Multiple Fixations

The purpose of this research is to determine the pigments in the bark and leaves of mangrove (Rhizophora mucronata), to analyze rate of color fastness in batik, level of consumer interest, and most effective pricing for the resulting batik products. The research was conducted between June 2015 and February 2016, and took place in Mangunharjo village, Tugu district, Semarang city, Indonesia. The pigment identification tests were performed in Laboratorium Terpadu Universitas Diponegoro, Indonesia. This research focused on the leaves and barks of mangrove plants. The leaves and barks were extracted to be used as dyeing agents, after which the batik fabrics were fixated using alum, limestone and lotus. This descriptive research employed UV-Vis spectrophotometry to identify pigment and Adobe Photoshop computer program to perform color fastness analysis. The result showed that chlorophyll is a pigment which contributes to the color green in leaves. Photochemical test results also show that the pigment associated to the blackish-green hue was tannin, andthat which was associated with red was flavonoid and quinone. The various colors were applied in batik dyeing process, which resulted in a range of color from yellow to dark brown. Color fastness test of batik dyed with mangrove-derived pigments on wash air dry, wash press dry, and wash sun dry using calico as fabric showed that alum and limestone fixated fabric had the least color fastness, while conversely, lotus-fixated fabric displayed good color retention. Levels of consumer interest naturally-dyed batik fabric by alum fixation was 20%. Of all the respondents, 46.67% showed interest in limestone-fixated batik, whereas 40% responded well with the lotus-fixated batik. Consumer acceptance levels for the mangrove-dyed batik fixated by alum, limestone, and lotus were 6.67%, 16.66% and 13.33% respectively. High consumer interest in fabric fixated by limestone and lotus was attributed to darker and stronger hues. The most effective price point suggested per 2.1 x 1 m of fabric was between IDR 200,000 to IDR 350,000

Pigment composition of the bright skin in the poison toad, Melanophryniscus rubriventris (Anura: Bufonidae) from Argentina

The determination of the basis of skin colour is important to better understand the evolutionary and ecological relevance of colour variation in aposematic species. Significant variation in bright skin colouration can be found between and within populations of the poison toad, Melanophryniscus rubriventris. In this study, we identified the pigments present in the skin in seven populations of the species in Argentina to determine pigment composition of bright colouration. Our analysis showed that at least four different primary pigments consisting of a suite of orange-red carotenes and yellow xanthophylls contribute to the bright skin colour in different populations of the species. Four carotenoids, Astaxanthin, β-Carotene, Canthaxanthin, and Lycopene were detected by comparison with available standards in skin tissues on each population. Four carotenoids were also detected but not identified. We provide evidence that differences in colouration between individuals and populations in Melanophryniscus rubriventris cannot be merely ascribed to differences in their skin pigment profiles (i.e. pigment types). We discuss alternative explanations and stress the need of more studies on complex mechanisms and interactions affecting the expression of skin colouration in poison frogs and toads.Fil: Bonansea, Maria Ines. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Heit, Cecilia. Universidad Nacional de Jujuy; ArgentinaFil: Vaira, Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Jujuy. Universidad Nacional de Jujuy. Centro de Investigaciones y Transferencia de Jujuy; Argentin