Photosynthesis: what color was its origin?

Recent studies using geological and molecular phylogenetic evidence suggest several alternative evolutionary scenarios for the origin of photosynthesis. The earliest photosynthetic group is variously thought to be heliobacteria, proteobacteria or a precursor of cyanobacteria, organisms whose photosynthetic pigments make them different colors.     

Haplotype composition at the color locus is a major genetic determinant of skin color variation in Vitis × labruscana grapes

Skin color is one of the most important fruit traits in grape, and has become greatly diversified due to hybridization and human selection. Many studies concerning the genetic control of grape color in European species (Vitis vinifera L.), especially the role of MYB-related genes, have been reported. On the other hand, there have been few studies of the MYB-related genes in grapes belonging to V.?×labruscana L.H. Bailey, a subgroup of grapes that originated from the hybridization of V. labrusca with V. vinifera. In the present study, we found a novel functional haplotype, HapE2 (consisting of the genes VlMYBA2 and VlMYBA1?C3), in diploid V.?×labruscana. Moreover, we developed a method to determine the haplotype compositions of tetraploid grapes by means of quantitative real-time PCR, and investigated the relationship between haplotype composition and skin color. The color locus in V.?×labruscana grapes usually consists of functional haplotypes (HapE1 and/or HapE2), and non-functional haplotype HapA. The number of functional haplotypes in the genome was found to be correlated with the level of anthocyanin in the skin. Anthocyanin contents of grapes that contained HapE2 were significantly higher than those containing HapE1. These results suggest that the number and kind of functional haplotypes at the color locus are the major genetic factors that determine skin color variation. These findings provide new knowledge about the unique genetic control of color in V.?×labruscana grapes, and should contribute to development of new cultivars that have the desired color and anthocyanin content.     

Why are female color polymorphisms rare in territorial damselflies?

In nonterritorial damselflies, females often come in multiple color morphs, perhaps because females with rare colors experience reduced sexual harassment, and thus have a frequency‐dependent fitness advantage, compared to females of the most common color morph, but such polymorphisms are rare in territorial species. We consider three hypotheses to explain the rarity of female color polymorphisms in territorial species: (a) misdirected male aggression, (b) poor male mate recognition, and (c) low mating harassment rates. The first hypothesis has some empirical support, and can account for the absence of andromorphs (i.e., females that resemble males), but does not explain the absence of multiple heteromorphs. We tested the second hypothesis by presenting females of two novel color morphs (green‐ or red‐banded abdomens) to territorial male Hetaerina capitalis. Females of both novel color morphs elicited fewer sexual responses than control females, and the red morph occasionally elicited aggressive responses. These results indicate that novel female color morphs would experience reduced mating harassment in this species, contradicting the hypothesis that male mate recognition is too poorly developed to reduce harassment of novel female morphs. By process of elimination, the third hypothesis, that harassment rates are too low in territorial species to provide rare female morphs a fitness advantage, is favored, but remains untested. Our findings also suggest that the common practice of color‐marking odonates for behavioral research is likely to interfere with mate choice, as has long been known to be the case in birds.     

Coat color aberrations inPresbytis johnii: A founder effect?

Individuals ofPresbytis johnii with coats of brown hair, rather than of the normal black color, are reported from a population inhabiting forest fragments at a low elevation in the Western Ghats of South India. It is suggested that this coat color aberration is due to a relatively rare recessive allele, occurring homozygously as a result of inbreeding in small, isolated populations. Because similar color aberrations in other colobine monkeys seem most frequent in isolated populations, they too may be the result of founder effects rather than recent mutation.     

Is the purple color of bacteriorhodopsin maintained by lipid-protein interactions?

When bacteriorhodopsin is delipidated and purified in detergents, its purple chromophore can be reversibly titrated to a red one. The pK_a of this equilibrium depends on the nature of the detergent in which bacteriorhodopsin is dispersed. In the absence of solvating amphiphiles, lipid-free detergent-free bacteriorhodopsin is red (λ_max = 480 nm) at pH higher than 3.5.     

The color phi phenomenon: Not so special,after all?

We show how anomalous time reversal of stimuli and their associated responses can exist in very small connectionist models. These networks are built from dynamical toy model neurons which adhere to a minimal set of biologically plausible properties. The appearance of a “ghost” response, temporally and spatially located in between responses caused by actual stimuli, as in the phi phenomenon, is demonstrated in a similar small network, where it is caused by priming and long-distance feedforward paths. We then demonstrate that the color phi phenomenon can be present in an echo state network, a recurrent neural network, without explicitly training for the presence of the effect, such that it emerges as an artifact of the dynamical processing. Our results suggest that the color phi phenomenon might simply be a feature of the inherent dynamical and nonlinear sensory processing in the brain and in and of itself is not related to consciousness.     

Is a "color effect" demonstrated for hair analysis of carbamazepine?

Psillakis et al. have reported on the concentration of carbamazepine recovered from hair samples collected from patients receiving this anti-seizure medication under medical supervision and determined that their was a high correlation between dose and quantitation of recovered analyte. The analyte was identified by two techniques, FPIA (Abbott TDx) and HPLC and the correlation was high for both procedures. In the literature on hair analysis some have suggested that analyte concentration in hair is critically dependent on hair color. In reporting their data Psillakis et al. reported the hair color of each patient but made no attempt to analyze their results in relation to color. This article performs a secondary analysis of the Psillakis et al. data in order to determine whether there is a hair color effect discernible in the recovery of carbamazepine from hair. Analysis of this data set for both the FPIA and HPLC by one-way analysis of variance fails to identify a color effect at p = .05. Weighting the data for per-patient dosage values fails to discern a color effect. Examination of all possible two-color comparisons also fails to identify a statistically significant effect for any subset of combinations. These data suggest that carbamazepine does not exhibit a color effect when using either FPIA or HPLC assay methods.     

Anthocyanin and pH in the color of ‘Heavenly Blue’ morning glory

The major anthocyanin in blue morning glory flowers, peonidin 3-(dicaffeylsophoroside)- 5-glucoside, is stable in a neutral aqueous solution and is solely responsible for the color of the flowers. Co-ocurring flavonols based on quercetin at the pH's of epidermal cells have no effect on the color of the anthocyanin. Deep or strong reddish-purple buds change to moderate or light blue open flowers within a 4 hr period, and during this time the pH of epidermal tissue increases from ca 6.5 to 7.5.     

Could diffuse coevolution explain the generic eggshell color of the brown-headed cowbird?

The brown-headed cowbird (hereafter cowbird) is an avian brood parasite that produces an egg dissimilar to those produced by the majority of its diverse host community. The cowbird’s generic egg may result from a Jack-of-all-trades strategy; however, the evolutionary mechanisms that select for their generic eggs are unclear. Here we propose that the cowbird’s eggshell phenotypes have evolved via diffuse coevolution, which results from community-level selective pressures, rather than via pairwise coevolution that occurs between a particular host species and its brood parasite. Under diffuse coevolution the cowbird’s host community, with varying eggshell phenotypes and recognition abilities, would select for a cowbird eggshell phenotype intermediate to those of its host community. This selection is exerted by hosts that reject cowbird eggs, rather than those that accept them; therefore, we expect cowbird eggshell colors can be approximated by both the phenotypes and rejection abilities of their host community. Here we use eggshell reflectance data from 43 host species to demonstrate that the cowbird eggshell phenotypes are reasonably predicted (within 2 just noticeable differences) by the eggshell phenotypes and rejection rates of their hosts. These findings suggest that cowbird eggshell phenotypes, and potentially those of other some generalist parasites, may evolve via diffuse coevolution. Importantly, this research provides insight into the underlying evolutionary processes that explain observed phenotypic variation and provides a framework for studying selection on both specialist and generalist parasites’ traits.     

Inheritance of unique fruit and foliage color mutation in NuMex piñata

The inheritance of mature fruit color in peppers (Capsicum spp.) is controlled by several genes. However, the inheritance of the transition of colors the fruit undergo during ripening has not been described extensively. The authors describe the inheritance of a unique gene which affects foliage color and fruit color transition occurring in the jalape?o cultivar NuMex Pi?ata. The gene responsible is designated the tra gene.     

“69 — Apricot” a synthetic strain of the mediterranean fruit fly,Ceratitis capitata [Dip.: Teprhitidae] with sex-limited pupal color and eye color marker

A true-breeding “69 — apricot” strain of the Mediterranean fruit fly,Ceratitis capitata Wied, has been established in the laboratory. The strain carries a Y-chromosome translocation and produces wild-type (brown) pupae in the male and mutant dark-pupae in the female. The adults have all an apricot eye color. Some components of the sexual behaviour were studied. The males did not differ from the wild-type males in their attraction to females or inseminating ability. They showed an inferior mating ability wich was attributed to their apricot eye color mutation.     

Can color vision variation explain sex differences in invertebrate foraging by capuchin monkeys?

Invertebrates are the main source of protein for many small-to-medium sized monkeys. Prey vary in size, mobility, degree of protective covering, and use of the forest, I.e. Canopy height, and whether they are exposed or embed themselves in substrates. Sex-differentiation in foraging patterns is well documented for some monkey species and recent studies find that color vision phenotype can also affect invertebrate foraging. Since vision phenotype is polymorphic and sex-linked in most New World monkeys - males have dichromatic vision and females have either dichromatic or trichromatic vision - this raises the possibility that sex differences are linked to visual ecology. We tested predicted sex differences for invertebrate foraging in white-faced capuchins Cebus capucinus and conducted 12 months of study on four free-ranging groups between January 2007 and September 2008. We found both sex and color vision effects. Sex: Males spent more time foraging for invertebrates on the ground. Females spent more time consuming embedded, colonial invertebrates, ate relatively more "soft" sedentary invertebrates, and devoted more of their activity budget to invertebrate foraging. Color Vision: Dichromatic monkeys had a higher capture efficiency of ex posed invertebrates and spent less time visually foraging. Trichromats ate relatively more "hard" sedentary invertebrates. We con clude that some variation in invertebrate foraging reflects differences between the sexes that may be due to disparities in size, strength, reproductive demands or niche preferences. However, other intraspecific variation in invertebrate foraging that might be mistakenly attributed to sex differences actually reflects differences in color vision.     

Seasonal changes in blue tit crown color: do they signal individual quality?

Plumage coloration is generally perceived as a static traitand therefore not a good indicator of current condition. However,changing of feather colors after molt does occur and may haveimportant implications for signal function and sexual selection.We studied longitudinal changes in blue tit (Parus caeruleus)crown ultraviolet (UV)/blue color, a sexually selected trait,by repeatedly measuring the same individuals between early winterand late spring. Whereas crown UV reflectance (UV chroma andhue) decreased dramatically over time, brightness and saturationdid not show consistent patterns of change. The magnitude ofthe decline in coloration exceeded sexual and age dichromatismin hue and UV chroma, respectively. Hence, seasonal color changescould have strong effects on blue tit sexual signaling. Between-individualvariation in the decline in UV coloration was large and relatedto attributes of male, but not female, quality, such as sizeand condition. Thus, conspecifics could potentially gain informationabout male phenotypic quality by assessing color change overthe year. However, the degree of decline in male UV color didnot affect breeding success because neither the number of within-pairnor the number of extrapair offspring produced correlated withchanges in crown color. Seasonal changes in the expression ofplumage coloration are probably widespread, and maintainingplumage coloration could thus constitute an additional honesty-enforcingmechanism after molt is completed.     

Do genetic structure and landscape heterogeneity impact color morph frequency in a polymorphic salamander?

Landscape heterogeneity plays an important role in population structure and divergence, particularly for species with limited vagility. Here, we used a landscape genetic approach to identify how landscape and environmental variables affect genetic structure and color morph frequency in a polymorphic salamander. The eastern red‐backed salamander, Plethodon cinereus, is widely distributed in northeastern North America and contains two common color morphs, striped and unstriped, that are divergent in ecology, behavior, and physiology. To quantify population structure, rates of gene flow, and genetic drift, we amplified 10 microsatellite loci from 648 individuals across 28 sampling localities. This study was conducted in northern Ohio, where populations of P. cinereus exhibit an unusually wide range of morph frequency variation. To test whether genetic distance was more correlated with morph frequency, elevation, canopy cover, waterways, ecological niche or geographic distance, we used resistance distance and least cost path analyses. We then examined whether landscape and environmental variables, genetic distance or geographic distance were correlated with variation in morph frequency. Tests for population structure revealed three genetic clusters across our sampling range, with one cluster monomorphic for the striped morph. Rates of gene flow and genetic drift were low to moderate across sites. Genetic distance was most correlated with ecological niche, elevation and a combination of landscape and environmental variables. In contrast, morph frequency variation was correlated with waterways and geographic distance. Thus, our results suggest that selection is also an important evolutionary force across our sites, and a balance between gene flow, genetic drift and selection interact to maintain the two color morphs.