scholarly journals Porphyrins produce uniquely ephemeral animal colouration: a possible signal of virginity

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Ismael Galván ◽  
Pablo R. Camarero ◽  
Rafael Mateo ◽  
Juan J. Negro
Keyword(s):  
Animal Colouration

Conspecifics of the Striped Lava Lizard are able to distinguish sex and male colour morphs in apparently homogeneous dull dorsal colouration

2019 ◽  
Vol 40 (2) ◽  
pp. 149-162 ◽  
Author(s):  
Andre C. Bruinjé ◽  
Mauricio O. Moura ◽  
Bruno S. Maggi ◽  
Vinicius A. São-Pedro ◽  
Daniel M.A. Pessoa ◽  
...  
Keyword(s):  
Body Region ◽  
Body Parts ◽  
Adult Males ◽  
Intraspecific Interactions ◽  
Body Regions ◽  
Animal Colouration ◽  
Colour Morphs ◽  
Lava Lizard ◽  
Uv Reflection ◽  
Colour Classes

Abstract Animal colouration plays a key role in inter and intraspecific interactions, pre-eminently in mate signalling. When multiple types of colouration occur within sexes it is possible that they show alternative reproductive strategies. In lizards, most colouration studies do not incorporate how colour is perceived by conspecifics. Here, we used unbiased colour analysis methods (spectrophotometry and visual modelling) to test for sexual dimorphism and within male dichromatism in the Striped Lava Lizard. We found that males express two distinct colourations that are different from females in several dorsal and ventral body regions. Our results showed UV reflection at the throat, an important body region for signalling. Ventral patches, the coloured badge seen in adult males of Tropidurus spp., have two distinct colour classes within males (Y and B males). Morphs are best discriminated by blue and yellow chroma, and brightness. Body size had little influence on colouration, suggesting that colour may be linked to inheritance rather than growth. Our study clearly shows sexual dichromatism and the existence of colour morphs in this species. Moreover, morph differences in colouration are perceptible by conspecifics. These differences are not only between ventral patches, but also in other body parts such as the dorsum, previously considered as cryptic by human observers. We suggest that colouration at the ventral patches and throat might play a role in intraspecific interactions. Patches increase colour intensity during breeding season and are likely to be costly by pigment-based expression, whereas throat’s UV reflection might have a cost infringed by conspicuousness.

scholarly journals Molecular vibration as a novel explanatory mechanism for the expression of animal colouration

2018 ◽  
Vol 10 (8) ◽  
pp. 464-473 ◽  
Author(s):  
Ismael Galván ◽  
Javier Cerezo ◽  
Alberto Jorge ◽  
Kazumasa Wakamatsu
Keyword(s):  
Molecular Vibration ◽  
Animal Colouration ◽  
Explanatory Mechanism

A bird that changes colour without moulting: how the wîskicâhk (Canada Jay, Perisoreus canadensis) tricked the taxonomists

2021 ◽  
Vol 99 (3) ◽  
pp. 183-195
Author(s):  
Dan Strickland ◽  
Stéphanie M. Doucet
Keyword(s):  
Spectral Analysis ◽  
North America ◽  
20Th Century ◽  
Colour Change ◽  
Early 20Th Century ◽  
Museum Specimens ◽  
Cautionary Tale ◽  
The Pacific ◽  
Perisoreus Canadensis ◽  
Animal Colouration

Avian and mammalian colours are thought to be constant in life and in museum specimens, but several early 20th-century taxonomists singled out the Canada Jay (Perisoreus canadensis (Linnaeus, 1766)) as having unstable feather pigments and warned against using old museum specimens for taxonomic purposes. One such error was Brisson’s (1760) original naming of the species as “the Brown Jay of Canada”. Another was Ridgway’s (1899) naming of the “Gray Jay” as a new subspecies, Perisoreus (canadensis) griseus, through inappropriate comparison of fresh grey specimens with old brown ones. We discovered that browning of initially grey plumage also occurs between annual moults in living individuals of the Canada Jay’s Pacific morphotype. We documented this change using photographs and re-sightings of colour-banded individuals and through spectral analysis of year-old (brown) and incoming (grey) rectrices collected from the same moulting individuals. To assess the distribution of this colour change, we compared September vs. May eBird photographs from across North America. We showed that seasonal colour change is normal in the Pacific morphotype but rare in the two other morphotypes. Collectively, these data have important implications for the taxonomy of the Canada Jay and are a cautionary tale for taxonomists studying animal colouration.

scholarly journals Quantifying pigment cover to assess variation in animal colouration

2017 ◽  
Vol 2 (1) ◽  
Author(s):  
Andjin Siegenthaler ◽  
Debapriya Mondal ◽  
Chiara Benvenuto
Keyword(s):  
High Precision ◽  
Digital Images ◽  
Behavioural Ecology ◽  
Crangon Crangon ◽  
Accuracy And Precision ◽  
Wide Range ◽  
Pigment Migration ◽  
Animal Colouration ◽  
User Friendly ◽  
Speed Accuracy

Abstract The study of animal colouration addresses fundamental and applied aspects relevant to a wide range of fields, including behavioural ecology, environmental adaptation and visual ecology. Although a variety of methods are available to measure animal colours, only few focus on chromatophores (specialized cells containing pigments) and pigment migration. Here, we illustrate a freely available and user-friendly method to quantify pigment cover (PiC) with high precision and low effort using digital images, where the foreground (i.e. pigments in chromatophores) can be detected and separated from the background. Images of the brown shrimp, Crangon crangon, were used to compare PiC with the traditional Chromatophore Index (CI). Results indicate that PiC outcompetes CI for pigment detection and transparency measures in terms of speed, accuracy and precision. The proposed methodology provides researchers with a useful tool to answer essential physiological, behavioural and evolutionary questions on animal colouration in a wide range of species.

scholarly journals Patterns of variations in dorsal colouration of the Italian wall lizard Podarcis siculus

Biology Open ◽  
2021 ◽  
Vol 10 (10) ◽  
Author(s):  
Federico Storniolo ◽  
Marco A. L. Zuffi ◽  
Alan J. Coladonato ◽  
Loris Di Vozzo ◽  
Gianni Giglio ◽  
...  
Keyword(s):  
Seasonal Variations ◽  
Great Variability ◽  
Model Species ◽  
Field Of Study ◽  
Excellent Model ◽  
Trade Offs ◽  
Animal Colouration ◽  
Podarcis Siculus ◽  
Italian Wall Lizard

ABSTRACT Research on animal colouration has grown exponentially in the last decade thanks to multidisciplinary approaches. Most studies are focused on trade-offs between communication and mimicry, which represent the two main constraints and drivers of the evolution of body colourations. Reptiles are excellent model species for investigating this field of study and lizards in particular show great variability of body colourations and their functions. We studied the lizard Podarcis siculus, analysing the variations of dorsal colour of three populations and obtained clear patterns of seasonal and ontogenetical variation of dorsal colour. According to baseline colour, males were greener and brighter than females, although no difference in saturation was recorded. According to seasonal variations, analyses showed that both sexes significantly vary in colour over the year: males reached higher peaks of hue and saturation later than females during spring, while females showed higher peaks of brightness and reached earlier similarly to hue and saturation. Ontogenetic variations were recorded only in males, which become greener, less bright and saturated with growing size. Therefore, our results suggest the occurrence of two opposing strategies in colour expression between sexes: males’ dorsal colouration plays a major role in communication, while females are more crypsis-oriented.

scholarly journals How Can We Record Reliable Information on Animal Colouration in the Wild?

Diversity ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 356
Author(s):  
Enrico Lunghi ◽  
Francesco Bacci ◽  
Yahui Zhao
Keyword(s):  
Reliable Information ◽  
Phenotypic Trait ◽  
Complete Darkness ◽  
Blue Channel ◽  
Animal Colouration ◽  
In The Wild ◽  
Analysis Of The Images ◽  
The Moment ◽  
Species Ecology

Animal colouration is a phenotypic trait that can provide important information on species ecology and adaptation. Describing animal colours can be very challenging, and digital images may help in this difficult task. Obtaining an image with colours similar to those observed in nature is not trivial, as many factors can alter the final result. Some studies highlighted the importance of a proper post-production and analysis of the images to obtain the best results, but unfortunately very little attention has been paid to how to obtain standardised images suitable to be employed in zoological and ecological studies. This study aims to give evidence about the importance of shooting pictures in standardised condition to obtain reliable data on animal colourations. We provide a method that allows to obtain standardised pictures with colours that are comparable to those observed on wild animals. We used a method that creates an in situ standardised environment to shoot photos of relatively small animals. Our method allows to fully control lights, the factor that affect pictures the most. We also provided a test on the efficiency of this method. Using a colour checker card as reference, we compared the divergence of the Red-Green-Blue channel values obtained from pictures shot in complete darkness with those read by a colorimeter. The average divergence in RGB values between the colorimeter and the RAW images was about 4%. This divergence increased when light disturbance occurred. Our method highlighted the importance of the moment in which pictures are taken, and demonstrated that a fully controlled method is essential for obtaining reliable information on animal colourations, data that can be employed in ecological and evolutionary studies.

scholarly journals Condition dependence in animal colouration: tools for a comparative approach

2016 ◽  
Author(s):  
Jessica Ethier ◽  
Emma Despland
Keyword(s):  
Resource Allocation ◽  
Theoretical Model ◽  
Linear Regression ◽  
Simple Equation ◽  
Condition Dependence ◽  
Comparative Approach ◽  
Regression Analyses ◽  
Proximate Mechanisms ◽  
The Past ◽  
Animal Colouration

The study of condition dependence in animal colour has undergone important changes in recent years. In particular, the focus on carotenoid-based colour traits is a thing of the past and a broader, comparative approach is becoming more common. Here, we refine a previously developed theoretical model describing pigment expression as a saturating function of resource intake and demonstrate its use as a tool to compare patterns of resource assimilation, resource allocation, and condition dependence between groups of organisms. Using a simple equation and non-linear regression analyses, we apply this saturating model to melanin-based colouration in a model insect species. We find that patterns of condition dependence differ between sexes, phenotypes, and populations, suggesting underlying differences in resource allocation priorities. Our results highlight both the usefulness of this method and the value of a comparative approach in identifying proximate mechanisms of condition dependence.

scholarly journals A quantitative analysis of objective feather colour assessment: measurements in the lab are more reliable than in the field

2014 ◽  
Author(s):  
Iker Vaquero-Alba ◽  
Andrew McGowan ◽  
Daniel Pincheira-Donoso ◽  
Matthew R. Evans ◽  
Sasha R.X. Dall
Keyword(s):  
Sampling Methods ◽  
Field Measurements ◽  
Human Vision ◽  
Visible Part ◽  
Uv Reflectance ◽  
Higher Power ◽  
Animal Colouration ◽  
Barn Swallows ◽  
Measuring Tool ◽  
High Repeatability

The evolution of animal colouration is importantly driven by sexual selection operating on traits used to transmit information to rivals and potential mates, which therefore, have major impacts on fitness. Reflectance spectrometry has become a standard colour-measuring tool, especially after the discovery of tetrachromacy in birds and their ability to detect UV. Birds? plumage patterns may be invisible to humans, necessitating a reliable and objective way of assessing colouration not dependent on human vision. Plumage colouration measurements can be taken directly on live birds in the field or in the lab (e.g. on collected feathers). Therefore, it is essential to determine which sampling method yields more repeatable and reliable measures, and which of the available quantitative approaches best assess the repeatability of these measures. Using a spectrophotometer, we measured melanin-based colouration in barn swallows? (Hirundo rustica) plumage. We assessed the repeatability of measures obtained with both traditional sampling methods separately to quantitatively determine their reliability. We used the ANOVA-based method for calculating the repeatability of measurements from two years separately, and the GLMM-based method to calculate overall adjusted repeatabilities for both years. We repeated the assessment for the whole reflectance spectrum range and only the human-visible part, to assess the influence of the UV component on the reliabilities of sampling methodologies. Our results reveal very high repeatability for lab measurements and a lower, still moderate to high repeatability, for field measurements. Both increased when limited to only the human-visible part, for all plumage patches except the throat, where we observed the opposite trend. Repeatability between sampling methods was quite low including the whole spectrum, but moderate including only the human-visible part. Our results suggest higher reliability for measurements in the lab and higher power and accuracy of the GLMM-based method. They also suggest UV reflectance differences amongst different plumage patches.

scholarly journals HIGH-RESOLUTION CHARACTERIZATION OF MALE ORNAMENTATION AND REEVALUATION OF SEX LINKAGE IN GUPPIES

2020 ◽  
Author(s):  
Jake Morris ◽  
Iulia Darolti ◽  
Wouter van der Bijl ◽  
Judith E. Mank
Keyword(s):  
High Resolution ◽  
Natural Populations ◽  
Colour Pattern ◽  
Sexually Dimorphic ◽  
Animal Colouration ◽  
In The Wild ◽  
Colour Changes ◽  
Colour Patterns ◽  
Male Ornaments

AbstractColouration plays a key role in the ecology of many species, influencing how an organism interacts with its environment, other species and conspecifics. Guppies are sexually dimorphic, with males displaying sexually selected colouration resulting from female preference. Previous work has suggested that much of guppy colour pattern variation is Y-linked. However, it remains unclear how many individual colour patterns are Y-linked in natural populations as much of the previous work has focused on phenotypes either not found in the wild, or aggregate measures such as total colour area. Moreover, ornaments have traditionally been identified and delineated by hand, and computational methods now make it possible to extract pixels and identify ornaments more automatedly, reducing the potential for human bias. Here we developed a pipeline for automated ornament identification and high-resolution image analysis of male guppy colour patterns and applied it to a multigenerational pedigree. Our results show that loci controlling the presence or absence of individual male ornaments in our population are not predominantly Y-linked. However, we find that ornaments of similar colour are not independent of each other, and modifier loci that affect whole animal colouration appear to be at least partially Y-linked. Considering these results, Y-linkage of individual ornaments may not be important in driving colour changes in natural populations of guppies, or in expansions of the non-recombining Y region, while Y-linked modifier loci that affect aggregate traits may well play an important role.

Sign in / Sign up

Export Citation Format

Share Document