Rapid divergence of social signal coloration across the White Sands ecotone for three lizard species under strong natural selection

Animal social signals are important for population recognition, communication, and mate choice. Although natural selection often favours cryptic coloration, sexual selection can underlie patterns of coloration that function in inter- or intrasexual communication. We compared social signal coloration of three lizard species across a substrate colour ecotone in New Mexico. These species exhibit cryptic blanched dorsal coloration on the gypsum dunes of White Sands and dark coloration on the surrounding desert soils. We detected corresponding population divergence in colour used for intra- ( Aspidoscelis inornata , Sceloporus undulatus ) or inter- ( Holbrookia maculata ) sexual signalling. Although the magnitude and direction of change in coloration varied among taxa, differences in hue and chroma accounted for more variation in social coloration than for dorsal coloration. The relative conspicuousness of social signals also varied across the ecotone. We discuss the possibilities that divergent signalling colours in this system are the result of: (1) stochastic processes, (2) direct selection, and/or (3) a correlated response to natural selection on dorsal coloration.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 243–255.     

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.     

Habitat structure and prey composition generate contrasting effects on carotenoid‐based coloration of great tit Parus major nestlings

Carotenoid‐based coloration of nestling plumage is generally considered a reliable signal of quality and has consistently been related to habitat structure. The main hypothesis proposed to explain this correlation is that high quality habitats contain high quality food, which in return affects the expression of carotenoid‐based plumage. It therefore assumes that, at the population level, the link between habitat structure and food composition is consistent and more relevant than inter‐individual differences in foraging ability or parental investment. In addition, it is assumed by default that food and habitat produce concordant effects on nestling coloration. In this work we evaluated habitat structure and prey composition in addition to several measures of parental investment. We investigated their relative effect on carotenoid‐based plumage coloration (lightness, chroma and hue) of great tit Parus major nestlings. We found a low correlation between carotenoid‐based coloration of nestlings and that of their parents. Nestling coloration, especially lightness and chroma, increased with the intake of more spiders. The time of breeding was positively correlated with lightness and chroma and negatively correlated with hue. Finally, the maturity of oak trees surrounding nest‐boxes correlated negatively with lightness, and the size of all tree species surrounding nest‐boxes correlated positively with hue of chick plumage. Our findings support the view that habitat structure and prey composition may produce divergent effects on feather pigmentation, and that prey proportions and variables related to parental investment should be assessed when considering carotenoid‐based coloration of chicks. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 547–555.     

Latitudinal variation in biophysical characteristics of avian eggshells to cope with differential effects of solar radiation

Solar radiation is an important driver of animal coloration, not only because of the effects of coloration on body temperature but also because coloration may protect from the deleterious effects of UV radiation. Indeed, dark coloration may protect from UV, but may increase the risk of overheating. In addition, the effect of coloration on thermoregulation should change with egg size, as smaller eggs have higher surface‐volume ratios and greater convective coefficients than larger eggs, so that small eggs can dissipate heat quickly. We tested whether the reflectance of eggshells, egg spottiness, and egg size of the ground‐nesting Kentish plover Charadrius alexandrinus is affected by maximum ambient temperature and solar radiation at breeding sites. We measured reflectance, both in the UV and human visible spectrum, spottiness, and egg size in photographs from a museum collection of plover eggshells. Eggshells of lower reflectance (darker) were found at higher latitudes. However, in southern localities where solar radiation is very high, eggshells are also of dark coloration. Eggshell coloration had no significant relationship with ambient temperature. Spotiness was site‐specific. Small eggs tended to be light‐colored. Thermal constraints may drive the observed spatial variation in eggshell coloration, which may be lighter in lower latitudes to diminish the risk of overheating as a result of higher levels of solar radiation. However, in southern localities with very high levels of UV radiation, eggshells are of dark coloration likely to protect embryos from more intense UV radiation. Egg size exhibited variation in relation to coloration, likely through the effect of surface area‐to‐volume ratios on overheating and cooling rates of eggs. Therefore, differential effects of solar radiation on functions of coloration and size of eggshells may shape latitudinal variations in egg appearance in the Kentish plover.     

The interplay between multiple predators and prey colour divergence

Evolutionary divergence in the coloration of toxic prey is expected when geographic variation in predator composition and behavior favours shifts in prey conspicuousness. A fundamental prediction of predator‐driven colour divergence is that the local coloration should experience lower predation risk than novel prey phenotypes. The dorsal coloration of the granular poison frog varies gradually from populations of conspicuous bright red frogs to populations of dull green and relatively cryptic frogs. We conducted experiments with clay models in four populations to examine the geographic patterns of taxon‐specific predation. Birds avoided the local phenotype while lizards consistently selected for decreased conspicuousness and crab predation did not depend on frog coloration. Importantly, birds and lizards favoured low conspicuousness in populations where relatively cryptic green morphs have evolved. This study provides evidence for the interplay among distinct selective pressures, from multiple‐predator taxa, acting on the divergence in protective coloration of prey species. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 580–589.     

Sex and age differences in reflectance and biochemistry of carotenoid‐based colour variation in the great tit Parus major

The plumage coloration in great tits (Parus major) is the subject of much behavioural and ecophysiological research, yet there is a lack of analyses of the natural colour variation and its mechanisms. We used reflectance spectrometry and high‐performance liquid chromatography to explore individual, sexual and age‐related variation in carotenoid coloration and pigmentation, paramount to the often presumed, but rarely substantiated, costs and ‘honesty’ of carotenoid displays. In adults, we found that sex was the strongest predictor of ‘brightness’ (higher in males) and of ‘hue’ (longer wavelength in females). There was no sex difference in ‘carotenoid chroma’ or carotenoid content of feathers which also was unrelated to adult age (1 or 2+ years) and condition. Similar patterns were revealed for nestlings. Regarding the biochemical ‘signal content’, ‘carotenoid chroma’, but not ‘hue’, was significantly related to the carotenoid content (lutein and zeaxanthin) of feathers. These results refute the previously assumed exaggeration of carotenoid pigmentation in male great tits, and question the condition‐dependence of carotenoid coloration in this species. However, the sexual dimorphism in total reflectance or ‘brightness’, most likely due to melanins rather than carotenoids, may have implications for signalling or other adaptive explanations that need to be explored. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 758–765.     

Phenotypic evolution in high‐elevation populations of western fence lizards (Sceloporus occidentalis) in the Sierra Nevada Mountains

Adaptive divergence in response to variable habitats, climates, and altitude is often accentuated along elevation gradients. We investigate phenotypic evolution in body size and coloration in the western fence lizard (Sceloporus occidentalis Baird & Girard, 1852) across elevation gradients in Yosemite National Park, California, situated in the Sierra Nevada mountains of Western North America. High‐elevation populations occurring above 2100 m a.s.l. are recognized as a separate subspecies (Sceloporus occidentalis taylori Camp, 1916), with a distinctive phenotype characterized by a large body size and extensive blue ventral pigmentation. We sampled S. occidentalis from across elevation gradients in Yosemite National Park, California, and collected phenotypic data (body size and ventral coloration measurements; 410 specimens) and mitochondrial DNA sequence data (complete NADH1 gene; 969 bp, 181 specimens) to infer phylogenetic relationships, and examine the genetic and phenotypic diversity among populations. Populations of S. occidentalis in Yosemite National Park follow Bergmann's rule and exhibit larger body sizes in colder, high‐elevation environments. The high‐elevation subspecies S. o. taylori is not monophyletic, and the mitochondrial DNA genealogy supports a model of convergent phenotypic evolution among high‐elevation populations belonging to different river drainages. The hypothesis that separate populations of S. occidentalis expanded up river drainages after the recession of glaciers is supported by population demographic analyses, and suggest that Bergmann's clines can evolve rapidly along elevation gradients. The distinctive high‐elevation phenotype that is attributable to S. o. taylori has evolved independently several times, and includes adaptive phenotypic changes associated with increases in body size and ventral coloration. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 630–641.     

Intraspecific variation in wing and pupal melanization in copper butterflies (Lepidoptera: Lycaenidae)

Melanin is a widespread pigment causing variation in skin darkness, with darker phenotypes typically reaching higher equilibrium temperatures than lighter ones. Therefore, selection is expected to favour darker phenotypes in colder environments. In the present study, we show intraspecific variation in pupal (and wing) melanization along an altitudinal gradient in two species of copper butterflies. Both, pupal and wing melanization increased with increasing altitude. Consistent with the thermal melanism hypothesis, darker (high-altitude) pupae reached higher equilibrium temperatures than paler (low-altitude) ones. However, as temperature differences were rather small despite pronounced differences in melanization, we cannot rule out that factors (e.g. ultraviolet protection, disease resistance) other than temperature comprise the principal selective agents. Mechanistically, variation in melanization might be related to variation in hormone titres, as demonstrated by low-altitude pupae showing higher ecdysteroid and juvenile hormone titres compared to high-altitude ones. Furthermore, we report sex differences in wing melanization, with males being darker than females, which is potentially related to a higher flight activity of males.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 301–312.     

Population differences in the structure and coloration of great tit contour feathers

Contour feathers cover most of the avian body and play critical roles in insulation, social communication, aerodynamics, and water repellency. Feather production is costly and the development of the optimum characteristics for each function may be constrained by limited resources or time, and possibly also lead to trade‐offs among the different characteristics. Populations exposed to different environmental conditions may face different selective pressures, resulting in differences in feather structure and coloration, particularly in species with large geographical distributions. Three resident populations of great tit Parus major L. from different latitudes differed in feather structure and coloration. Individuals from the central population exhibited less dense and longer contour feathers, with a higher proportion of plumulaceous barbs than either northern or southern birds, which did not differ in their feather structure. Ultraviolet reflectance and brightness of the yellow of the contour feathers of the breast was higher for the southern than for the northern population. Birds with greener plumage (higher hue) had less dense but longer feathers, independently of the population of origin. Differences in feather structure across populations appear to be unrelated to the contour feather colour characteristics except for hue. Nutritional and time constraints during molt might explain the pattern of feather structure, whereas varying sexual selection pressure might underlie the coloration patterns observed. Our results suggest that different selective pressures or constraints shape contour feather traits in populations exposed to varying environmental conditions. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 82–91.     

Altitudinal variation of UV-absorbing compounds in Plantago asiatica

UV-absorbing compounds such as flavonoids and phenolic acids are important for plants to protect their vegetative organs from harmful UV radiation at higher altitude. Two chemotypes, i.e., acteoside mainly-containing (AM) type and plantamajoside mainly-containing (PM) type were found by qualitative HPLC analysis of the phenolics in the leaves of Plantago asiatica in Mt. Norikura, Japan. Though AM type was not detected in low altitude populations, it occurred in high altitude populations. Acteoside has been reported to be more effective antioxidant than plantamajoside. On the other hand, higher accumulations of UV-absorbing substances were seen in higher altitude populations by quantitative analyses. Besides, B-ring ortho-dihydroxylated flavonoids notably increased than mono-hydroxylated flavonoids with increasing altitude. These results demonstrate that P. asiatica has chemically acclimated to high altitudes, in which severe environmental conditions such as higher UV radiation exist.     

Conspicuous blue tails,dorsal pattern morphs and escape behaviour in hatchling Iberian wall lizards (Podarcis hispanicus)

Predation has profound effects on the phenotypes of animal prey and, in lizards, the relationship between coloration and antipredatory behaviour has been studied in depth. However, studies that address the relationships between dorsal patterns and tail coloration with escape behaviour in polymorphic lizards are absent in the literature. We describe dorsal morphs and measured tail coloration and escape behaviour in hatchling Iberian wall lizards, Podarcis hispanicus, a species with a previously undescribed female‐restricted dorsal polymorphism (reticulated‐blotched males, and either striped or reticulated‐blotched females) and juvenile tails with conspicuous blue coloration, which is probably used to divert predator attacks towards the autotomizable tail. Overall we provide evidence for the existence of sexual dimorphism in tail ultraviolet reflectance between reticulated females and males, with striped females being intermediate. We identified sex/dorsal morph, body size and tail brightness as predictors of different aspects of escape behaviour and suggest the existence of two alternative escape strategies between striped and reticulated‐blotched females that may be dependent on dorsal morph differences, independently of sex. Reticulated‐blotched females, and also males (all reticulated‐blotched), ran faster and spent less time paused than striped females, which might reflect an escape behaviour strategy based on endurance in striped females. In addition, lowland males displayed tail waving as a ‘last resort’ antipredator strategy that may be related to fatigue. We concluded that hatchling antipredatory behaviour is influenced by both dorsal pattern and tail conspicuousness. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 1094–1106.     

Testing the role of background matching and self‐shadow concealment in explaining countershading coloration in wild‐caught rainbowfish

Countershading, or dorsal pigmentary darkening (DPD), describes a form of vertically varying coloration, where an animal typically has a dark dorsal surface and a paler ventral side, and is widespread among mammals, birds, reptiles, fishes and insects. DPD is thought to confer concealment from predators and, in terrestrial systems, there is good evidence that the dark–light transition in body coloration acts to conceal the body's shadow. Surprisingly few studies of DPD have been conducted in aquatic environments, and thus it is not known whether the mechanisms of concealment are similar to those that operate in terrestrial habitats. In this study, we determined the role of the light environment and predation risk in determining DPD in wild‐caught populations of a freshwater fish, the western rainbowfish (Melanotaenia australis). We also examined the underlying mechanisms of DPD for concealment by testing the assumptions of background matching and self‐shadow concealment. In a subsequent experiment, we determined whether any observed variation in DPD was maintained when the visual background was manipulated in the laboratory (to induce a change in body coloration). We found that both the amount of downwelling irradiance and the level of predation risk at the collection site affected skin darkness (dorsal, ventral and overall), whereas the ratio of dorsoventral coloration (DPD) was not affected by the parameters considered. The laboratory experiment revealed that fish changed their body coloration to match their visual background, and did so by altering the relative ratio of dorsoventral skin darkness. In contrast with research on terrestrial animals, our findings suggest that the most likely method of achieving crypsis is through background matching, rather than self‐shadow concealment. It is thus possible that differences in the optical characteristics of terrestrial and aquatic environments, and/or variation in the angles at which prey are typically viewed and attacked, have resulted in divergent mechanisms of using DPD to attain crypsis. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 915–928.     

Environmental correlates of internal coloration in frogs vary throughout space and lineages

Internal organs of ectotherms have melanin‐containing cells that confer different degrees of coloration to them. Previous experimental studies analyzed their developmental origin, role in immunity, and hormonal regulation. For example, melanin increases with ultraviolet radiation (UV) and temperature in frogs and fish. However, little is known about how environmental variables influence the amount of coloration on organs among amphibian species over a large spatial extent. Here, we tested how climatic variables (temperature, UV, and photoperiod) influence the coloration of internal organs of anurans. We recorded the level of melanin pigmentation using four categories on 12 internal organs and structures of 388 specimens from 43 species belonging to six anuran families. Then, we tested which climatic variables had the highest covariation with the pigmentation on each organ after controlling for spatial autocorrelation in climatic variables and phylogenetic signal in organ coloration using the extended version of the RLQ ordination. Coloration in all organs was correlated with the phylogeny. However, the coloration of different organs was affected by different variables. Specifically, the coloration of the heart, kidneys, and rectum of hylids, Rhinella schneideri, some Leptodactylus, and Proceratophrys strongly covaried with temperature and photoperiod, whereas that of the testicle, lumbar parietal peritoneum, lungs, and mesenterium of Leiuperinae, Hylodidae, Adenomera, and most Leptodactylus had highest covariation with UV‐B and temperature. Our results support the notion that melanin pigmentation on the surface of organs of amphibians has an adaptive function conferred by the protective functions of the pigment. But most importantly, internal melanin seems to respond differently to climatic variables depending on the lineage and locality in which species occur.     

Melanin‐based coloration of sneaker male Atlantic salmon is linked to viability and emergence timing of their offspring

The ‘good genes’ hypothesis of sexual selection predicts that male ornaments are favoured by female mate choice because male ornament reveals genetic quality. In species with different male reproductive tactics, variation in genetic quality among ‘sneaking’ males has rarely been investigated, as usually ‘sneakers’ are thought not to be chosen by females. Here we focused on the alternative reproductive tactic in Atlantic salmon (Salmo salar Linnaeus, 1758) to test whether the skin colour of sneakers may reveal the performance traits of their offspring. A fully factorial breeding design was realized between 20 sneakers and two females using in vitro fertilization. We quantified the red and dark colorations of males and measured the survival of their progeny under semi‐natural conditions. In addition, the size of offspring and their emergence timing from the gravel nest were monitored in the laboratory. We found that darker males sired more viable offspring, whereas red coloration was negatively correlated with offspring survival. Nevertheless, darker and redder male pigmentations were linked to a delay in offspring emergence. These results demonstrate that colours can reveal individual genetic quality in an alternative male reproductive tactic, with male melanin‐based coloration being linked to both beneficial and detrimental effects for the offspring. Our results imply that sneaker ornaments may potentially play a role in both intra‐ and intersexual selection. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 126–135.     

Observations on skin colour changes in juvenile lumpsuckers

This study reports on an experimental investigation of colour change in young lumpsuckers Cyclopterus lumpus , employing Munsell colour charts to quantify skin hue, colour value and chroma. Juvenile lumpsuckers can live pelagically close to the sea surface, or can attach to floating seaweed and debris with their suckers. When swimming they adopt a cryptic default light green coloration, with the dorsum being darker than the belly (countershading). This default colour is also seen in complete darkness. When attached to objects they take a colour stimulus from below and to the sides and change colour. They can achieve good colour matches (noticeable in 3 min; complete within 15 min) with substrata that are green-yellow in colour, especially the brown alga Ascophyllum nodosum . Colour matching is largely dependent upon changes in colour value (i.e. lightness/darkness) produced by melanin dispersal or concentration in the melanophores. Thus, on artificial backgrounds outside the range of achievable hue matching, they still achieve good matchings of colour value. Slight hue changes were recorded (probably reflecting interaction of basic skin colour with melanin dispersal state), but chroma (brightness) variations were negligible. Lumpsucker colour depends upon light intensity, allowing sustained colour matching as weed illumination changes.     

Developmental responses to UV-B radiation in common frog <Emphasis Type="Italic">Rana temporaria</Emphasis> embryos from along an altitudinal gradient

Solar ultraviolet radiation (UV) is harmful for developing amphibians. As UV increases with altitude and latitude, it is suggested that high altitude and latitude populations have evolved tolerance to high levels of UV. Using laboratory experiments, we tested the hypothesis that Rana temporaria populations from several altitudes (438–2,450 m above sea level) were adapted to UV by assessing the effects of artificial UV on embryos mortality rate, malformations, and body length at hatching. We also tested the protective role of the jelly surrounding the embryos. Without artificial UV exposure, hatching success decreased with altitude of the population. Malformation rates were low for all populations (mean 1.36%), and hatching size increased with altitude. The artificial UV (UV-B, UV-A, and visible) used was similar to the solar spectrum received at high altitude. Exposed embryos had performance similar to that of embryos without exposure: a decreased hatching success with altitude and a low malformation rate (mean 0.85%). However, hatching size did not vary with altitude, and UV-exposed embryos tended to be smaller at hatching than non-exposed embryos. Removal of the protective jelly envelope greatly decreased the performance of UV-exposed embryos: hatching success strongly decreased with altitude and embryos of the highest population (2,450 m asl) did not develop. Malformation reached 4.98%, without population differences, and hatching size of embryos without jelly was smaller than hatching size of non-manipulated embryos with no population effect. This study demonstrates that lowland jellyless embryos were less sensitive (i.e., exhibited a higher survival rate) than highland embryos and, on the other hand, that the jelly envelope was a more efficient protection for embryos in highland than in lowland populations. A trade-off hypothesis is presented to explain this difference in UV tolerance and protection among populations: in a harsh, highland environment (i.e., with a curtailed activity period), embryos have to invest in development and growth and, thus, embryo protection should be a female investment (via the jelly). In a lowland environment, embryonic growth and development are less constrained and embryos are able to invest and use protection or repair mechanisms inherited from their parents.     

Temperature is the key to altitudinal variation of phenolics in Arnica montana L. cv. ARBO

Plants in alpine habitats are exposed to many environmental stresses, in particular temperature and radiation extremes. Recent field experiments on Arnica montana L. cv. ARBO indicated pronounced altitudinal variation in plant phenolics. Ortho-diphenolics increased with altitude compared to other phenolic compounds, resulting in an increase in antioxidative capacity of the tissues involved. Factors causing these variations were investigated by climate chamber (CC) experiments focusing on temperature and ultraviolet (UV)-B radiation. Plants of A. montana L. cv. ARBO were grown in CCs under realistic climatic and radiation regimes. Key factors temperature and UV-B radiation were altered between different groups of plants. Subsequently, flowering heads were analyzed by HPLC for their contents of flavonoids and caffeic acid derivatives. Surprisingly, increased UV-B radiation did not trigger any change in phenolic metabolites in Arnica. In contrast, a pronounced increase in the ratio of B-ring ortho-diphenolic (quercetin) compared to B-ring monophenolic (kaempferol) flavonols resulted from a decrease in temperature by 5°C in the applied climate regime. In conclusion, enhanced UV-B radiation is probably not the key factor triggering shifts in the phenolic composition in Arnica grown at higher altitudes but rather temperature, which decreases with altitude.     

Altitudinal variation of secondary metabolites in flowering heads of the Asteraceae: trends and causes

Plants in alpine habitats are exposed to severe environmental stresses including temperature and radiation extremes. The observation that flowering heads from high altitude populations of Scorzoneroides helvetica (Mérat) J.Holub (synonym: Leontodon helveticus Mérat) contained higher amounts of luteolin derivatives than conspecific populations in lower altitudes prompted further investigations. An elevational increase of phenolics was confirmed in flowering heads of neophytic populations of three additional taxa of the Cichorieae tribe in New Zealand. A solely genetic basis of the altitudinal trends of flavonoids and phenolic acids was eliminated by field experiments with cultivars of the medicinal herbs Arnica montana L. and Matricaria chamomilla L. planted at nine different altitudes ranging from 600 to 2,200 m in the Tyrolean Alps. Parallel experiments on potted plants excluded soil characteristics as the factor causing the observed variation. The initial hypotheses that enhanced UV-B radiation in higher altitudes was triggering an increase in the ratio of B-ring-ortho-diphenolic versus B-ring-monophenolic flavonols in flowering heads of Arnica was disproved by climate chamber experiments resulting in no significant difference between plants grown in ambient and threefold ambient UV-B radiation regimes. In contrast, an increase of this ratio similar to the changes observed in higher altitudes resulted from a decrease in temperature by 5°C in a second climate chamber experiment. Conclusively, enhanced UV-B radiation is probably not the key factor inducing shifts in the phenolic composition in Asteraceae growing at higher altitudes but it is rather the temperature which decreases with altitude.     

The Effect of Ultraviolet and Solar Radiation and Temperature on Survival of Fungal Propagules

Survival of spores, spore aggregates, sclerotia, and pycnidia of fungi was evaluated after exposure to high temperature in the dark, or exposure to ultraviolet (UV) radiation or sunlight. Under most conditions survival decreased from the most resitant Sclerotium rolfsii to Alternaria macrospora, Mycosphaerella pinodes, Aspergillus niger and Botrytis cinerea, in that order. There was no difference in survival among organisms stored in darkness at 45°C as single spores or aggregated into a mass of spores; or between spores of M. pinodes exposed before and after being released from pycnidia. Exposure to UV reduced survival much more than exposure in darkness. Longevity under UV ranged from more than 7 days for S. rolfsii to approximately 50 min for A. macrospora and 3 min for B. cinerea. Much longer survival occurred for spores of all fungi aggregated together; of spores of M. pinodes irradiated when inside rather than outside pycnidia; and in bigger, darker and older rather than in smaller, paler and younger sclerotia of S. rolfsii. Survival of sclerotia cut into slices and exposed to UV increased with thickness, irrespective of exposure to UV with the outer pigmented or innernonpigmented side. As tested with spore aggregates of A. niger, the rate of survival was linearly proportional to the number of conidia aggregated in each body. Irradiation by sunlight affected survival as described for irradiation by UV. The best protection from the detrimental effects of sun and UV radiation was provided by the infected host tissue.     

High‐temperature inhibition of biosynthesis and transportation of anthocyanins results in the poor red coloration in red‐fleshed Actinidia chinensis

In plants, the role of anthocyanins trafficking in response to high temperature has been rarely studied, and therefore poorly understood. Red‐fleshed kiwifruit has stimulated the world kiwifruit industry owing to its appealing color. However, fruit in warmer climates have been found to have poor flesh coloration, and the factors responsible for this response remain elusive. Partial correlation and regression analysis confirmed that accumulative temperatures above 25°C (T25) was one of the dominant factors inhibiting anthocyanin accumulation in red‐fleshed Actinidia chinensis, ‘Hongyang’. Expression of structural genes, AcMRP and AcMYB1 in inner pericarp sampled from the two high altitudes (low temperature area), was notably higher than the low altitude (high temperature area) during fruit coloration. AcMYB1 and structural genes coordinate expression supported the MYB–bHLH (basic helix‐loop‐helix)–WD40 regulatory complex mediated downregulation of anthocyanin biosynthesis induced by high temperatures in kiwifruit. Moreover, cytological observations using the light and transmission electronic microscopy showed that there were a series of anthocyanic vacuolar inclusion (AVI)‐like structures involved in their vacuolization process and dissolution of the pigmented bodies inside cells of fruit inner pericarp. Anthocyanin transport was inhibited by high temperature via retardation of vacuolization or reduction in AIV‐like structure formation. Our findings strongly suggested that complex multimechanisms influenced the effects of high temperature on red‐fleshed kiwifruit coloration.