Variation In Plumage Coloration Research Articles

The genomic architecture of continuous plumage colour variation in the European barn owl (Tyto alba).

The maintenance of colour variation in wild populations has long fascinated evolutionary biologists, although most studies have focused on discrete traits exhibiting rather simple inheritance patterns and genetic architectures. However, the study of continuous colour traits and their potentially oligo- or polygenic genetic bases remains rare in wild populations. We studied the genetics of the continuously varying white-to-rufous plumage coloration of the European barn owl (Tyto alba) using a genome-wide association approach on the whole-genome data of 75 individuals. We confirmed a mutation at the melanocortin-1-receptor gene (MC1R) is involved in the coloration and identified two new regions, located in super-scaffolds 9 and 42. The combination of the three regions explains most of the colour variation (80.37%, 95% credible interval 58.45-100%). One discovered region, located in the sex chromosome, differs between the most extreme colorations in owls sharing a specific MC1R genotype. This region may play a role in the colour sex dimorphism of this species, possibly in interaction with the autosomal MC1R. We thus provide insights into the genetic architecture of continuous colour variation, pointing to an oligogenic basis with potential epistatic effects among loci that should aid future studies understanding how continuous colour variation is maintained in nature.

Mutations in SLC45A2 lead to loss of melanin in parrot feathers.

Bird plumage coloration is a complex and multifactorial process that involves both genetic and environmental factors. Diverse pigment groups contribute to plumage variation in different birds. In parrots, the predominant green color results from the combination of 2 different primary colors: yellow and blue. Psittacofulvin, a pigment uniquely found in parrots, is responsible for the yellow coloration, while blue is suggested to be the result of light scattering by feather nanostructures and melanin granules. So far, genetic control of melanin-mediated blue coloration has been elusive. In this study, we demonstrated that feather from the yellow mutant rose-ringed parakeet displays loss of melanosome granules in spongy layer of feather barb. Using whole genome sequencing, we found that mutation in SLC45A2, an important solute carrier protein in melanin synthetic pathway, is responsible for the sex-linked yellow phenotype in rose-ringed parakeet. Intriguingly, one of the mutations, P53L found in yellow Psittacula krameri is already reported as P58A/S in the human albinism database, known to be associated with human OCA4. We further showed that mutations in SLC45A2 gene affect melanin production also in other members of Psittaculidae family such as alexandrine and plum-headed parakeets. Additionally, we demonstrate that the mutations associated with the sex-linked yellow phenotype, localized within the transmembrane domains of the SLC45A2 protein, affect the protein localization pattern. This is the first evidence of plumage color variation involving SLC45A2 in parrots and confirmation of associated mutations in the transmembrane domains of the protein that affects its localization.

Survival of a polymorphic species in seasonally snow‐covered forests

Color polymorphism is an adaptive strategy in which a species exhibits multiple color phenotypes in a population. Often, phenotypes are variably suited to different environmental conditions which may buffer the population against variable conditions. Modern climate change is creating novel selective pressures for many species, especially in winter habitats. Few studies have quantified the benefits of polymorphism for allowing species to cope with climate‐induced environmental change, particularly for species with more cryptic differences between morphs. We investigated how color polymorphism mediates selective pressures in ruffed grouse Bonasa umbellus, a winter‐adapted bird species of North American forests. Ruffed grouse display phenotypic variation in plumage color, ranging from red to gray. Over five winters (2015–2022), we monitored weather conditions, habitat use, and weekly survival for 94 grouse to test whether individuals had lower survival when phenotypically mismatched with snow cover (e.g. a gray bird on a snowless landscape or a red bird in snow). Grouse phenotypically mismatched with snow cover had lower survival, but only when winter survival rates were lowest. During winters of lower overall survival, red grouse exhibited higher survival during snow‐free periods, whereas gray grouse had higher survival when snow was present. We also found that open habitat negatively impacted survival, regardless of color. While the effect of phenotypic mismatch was variable among years, it was a stronger predictor of survival than land cover, suggesting that snow is an important habitat feature mediating overwinter survival. Our work offers an advancement in understanding how environmental variability affects geographic variation in and maintenance of multiple color phenotypes in seasonally‐snow covered environments. Our finding that interactions between color morph and snow cover are important for conferring winter survival provides further evidence that color polymorphism may serve as a buffer against rapidly changing conditions and a pathway for persistence of polymorphic species.Keywords: Bonasa umbellus, color polymorphism, phenotypic mismatch, ruffed grouse, winter ecology, Wisconsin

An allelic series at the EDNRB2 locus controls diverse piebalding patterns in the domestic pigeon.

Variation in pigment patterns within and among vertebrate species reflects underlying changes in cell migration and function that can impact health, reproductive success, and survival. The domestic pigeon (Columba livia) is an exceptional model for understanding the genetic changes that give rise to diverse pigment patterns, as selective breeding has given rise to hundreds of breeds with extensive variation in plumage color and pattern. Here, we map the genetic architecture of a suite of pigmentation phenotypes known as piebalding. Piebalding is characterized by patches of pigmented and non-pigmented feathers, and these plumage patterns are often breed-specific and stable across generations. Using a combination of quantitative trait locus mapping in F2 laboratory crosses and genome-wide association analysis, we identify a locus associated with piebalding across many pigeon breeds. This shared locus harbors a candidate gene, EDNRB2, that is a known regulator of pigment cell migration, proliferation, and survival. We discover multiple distinct haplotypes at the EDNRB2 locus in piebald pigeons, which include a mix of protein-coding, noncoding, and structural variants that are associated with depigmentation in specific plumage regions. These results identify a role for EDNRB2 in pigment patterning in the domestic pigeon, and highlight how repeated selection at a single locus can generate a diverse array of stable and heritable pigment patterns.

Ecological factors drive the divergence of morphological, colour and behavioural traits in cactus wrens (Aves, Troglodytidae).

The study of ecological mechanisms influencing organisms' phenotypic variation is a central subject of evolutionary biology. In this study, we characterized morphological, plumage colour and acoustic variation in cactus wrens Campylorhynchus brunneicapillus throughout its distribution. We assessed whether Gloger's, Allen's and Bergmann's ecogeographical rules, and the acoustic adaptation hypothesis relate to geographical trait variation. We analysed specimen coloration in belly and crown plumage, beak shape and structural song characteristics. We tested whether the subspecific classification or the peninsular/mainland groups mirrored the geographical variation in phenotypes and whether ecological factors were associated with patterns of trait variation. Our results suggest that colour, beak shape and acoustic traits varied across the range, in agreement with two lineages described by genetics. The simple versions of Gloger's and Allen's rules are related to variations in colour traits and morphology. Conversely, patterns of phenotypic variation did not support Bergmann's rule. The acoustic adaptation hypothesis supported song divergence for frequency-related traits. Phenotypic variation supports the hypothesis of two taxa: C. affinis in the Baja California peninsula and C. brunneicapillus in the mainland. The ecological factors are associated with phenotypic trait adaptations, suggesting that divergence between lineages could result from ecological divergence.

Genome-Wide Association Study Reveals the Genetic Basis of Duck Plumage Colors.

Plumage color is an artificially and naturally selected trait in domestic ducks. Black, white, and spotty are the main feather colors in domestic ducks. Previous studies have shown that black plumage color is caused by MC1R, and white plumage color is caused by MITF. We performed a genome-wide association study (GWAS) to identify candidate genes associated with white, black, and spotty plumage in ducks. Two non-synonymous SNPs in MC1R (c.52G>A and c.376G>A) were significantly related to duck black plumage, and three SNPs in MITF (chr13:15411658A>G, chr13:15412570T>C and chr13:15412592C>G) were associated with white plumage. Additionally, we also identified the epistatic interactions between causing loci. Some ducks with white plumage carry the c.52G>A and c.376G>A in MC1R, which also compensated for black and spotty plumage color phenotypes, suggesting that MC1R and MITF have an epistatic effect. The MITF locus was supposed to be an upstream gene to MC1R underlying the white, black, and spotty colors. Although the specific mechanism remains to be further clarified, these findings support the importance of epistasis in plumage color variation in ducks.

Island volcanism predicts pheomelanin‐based plumage colouration in a cosmopolitan raptor

AbstractAimPheomelanin is a pigment responsible for yellowish‐to‐reddish colours of vertebrate teguments. Its biosynthesis is favoured under high concentration of intracellular thiols, which, in turn, can depend on the environmental exposure to sulphur. Thus, pheomelanin production should be more intense and frequent in environments characterized by high level of sulphur, such as volcanic regions. In this study, we aimed at addressing this hypothesis by investigating variation in plumage colour of insular populations of the cosmopolitan barn owl (Tyto alba species complex) according to the presence of soils of volcanic origin (i.e. andosols) and recent volcanic activity.LocationWorld.TaxonBarn owl species complex.MethodsWe measured plumage colouration of more than 2000 museum specimens from 50 islands and archipelagos worldwide. We then compared plumage colouration between populations living on volcanic (i.e. where andosols and/or recent volcanic activity are present) and non‐volcanic islands/archipelagos.ResultsConsistently with the prediction, plumage colouration is significantly darker (i.e. pheomelanic) on islands/archipelagos where andosols and/or recent volcanic activity are present than absent, although this environmental factor explains a small fraction of plumage colour variability across islands (<10%). Similar results were obtained when specimens' sex and climatic predictors were included in the analyses.Main ConclusionsBecause excessive intracellular levels of thiols can be toxic, pheomelanin synthesis may function as a mechanism keeping these compounds below the toxicity threshold and limiting their detrimental effects on physiology. Darker plumage may also be favoured because it promotes background matching against the dark environment typical of volcanic islands (dense vegetation cover and/or dark soil). Our results add to the little evidence that the environmental exposure of compounds that are involved in melanin biosynthesis can affect animal pigmentation and suggest that soil composition may be a factor that affects melanogenesis, possibly contributing to generate spatial variation in pheomelanin‐based traits in animals.

A new bunting species in South China revealed by an integrative taxonomic investigation of the Emberiza godlewskii complex (Aves, Emberidae)

Species boundaries of birds across the Euro-Asian continent, especially the widely distributed passerines with multiple subspecies, are not completely resolved. The Rock Bunting complex, Emberiza cia and E. godlewskii, is subject to ongoing debate due to geographic variation in its morphology, and deep genetic splits. In this study, the phylogenetic relationships of the E. cia/godlewskii complex were evaluated based on multilocus coalescence methods combined with analyses of plumage color and morphological variation. Although the northern and southern populations of E. godlewski formed reciprocally monophyletic groups, the northern E. godlewskii clade is the sister group to E. cia, rendering E. godlewskii as currently defined paraphyletic. The significant differences in morphometry and plumage color reflectance are complementary and support the phenotypic validity of northern and southern E. godlewskii. Thus, we recommend the following taxonomic revisions: the northern and southern E. godlewskii subspecies should be recognized as different full species, such as E. godlewskii and E. yunnanensis, respectively. This resolves the issue that E. godlewskii, as currently defined, is paraphyletic. Our research provides direct evidence of cryptic species in old world buntings and highlights the underestimation of species diversity in birds in East Asia.

Assessment of phenotypic diversity within Goliath chickens population in Benin.

Goliath chickens are a new strain of poultry that originated in the department of Zou, commune of Agbangnizoun in the Republic of Benin. The characteristics of this chicken strain have not been well studied. The purpose of this study was to characterize the phenotypic diversity of Goliath chickens in departments of Zou and Couffo. A total of 140 birds made up of 92 females and 48 males were sampled using 18 morphological descriptors. The results showed a wide variation in plumage colour within overall population with the most dominant being black (18.57%), white (17.14%) and red (16.43%). Black (21.74%) and white (20.65%) plumage dominated in females and red in males (35.42%). Coloured beaks and shanks were common in both chicken sexes. Yellow eyes were more common in females (63.04%), while red eyes were the most prevalent in males (43.75%). Comb and wattle colours were red in both sexes. Morphometrically, sexual dimorphism is very marked most of the body measurements with male birds being significantly superior. The average body weight was 3.26kg in males and 2.78kg in females. The population was clustered in three morphotypes according to the gradient size. Chickens from Bohicon and Agbangnizoun on the one hand, and those from Zagnanado and Toviklin on the other, formed groups 1 and 2, respectively, while group 3 included individuals from Djidja. 77.96% of observed diversity was due to variation between individuals. Molecular characterization is recommended for a thorough knowledge of the Goliath chicken strain of Benin.

Pleiotropic opposing dominance within a color gene block contributes to a nascent species boundary via its influence on hybrid male territorial behavior.

The divergence of plumage color genes contributes to songbird radiation. However, the mechanisms by which color gene divergence counteracts gene flow to maintain reproductive isolation during the formation of new species boundaries remain elusive. The hybrid zone between Setophaga occidentalis (SOCC) and S. townsendi (STOW) in the Cascade Range provides a natural observatory to investigate potential behavioral mechanisms underlying divergent selection on color genes. Recently, we found that selection within a single gene block associated with plumage color variation has maintained a stable and narrow hybrid zone. Here, we investigated the potential role of plumage signals in moderating a behavioral mechanism of selection. Specifically, we assessed whether two plumage traits are associated with body size among breeding males and if trait mismatch predicted aggressive behavior within hybrid and parental individuals in response to simulated territorial intrusion. The two plumage signals, cheek and flank coloration, though associated with the same gene block, reflect opposing dominance of SOCC and STOW alleles. We found that both plumage traits significantly predict the body size in the territorial sex (i.e. males). The opposing dominance of the single color gene block resulted in plumage signal discordance in heterozygotes, which in turn was associated with reduced hybrid territorial performance, an important proxy of fitness in this system. Taken together, these observations point to a single-locus-two-alleles mechanism of incompatibility in shaping a natural species boundary in the early stage of speciation.

Out of the blue: geographic variation and divergence between Azure Jays (Cyanocorax caeruleus) from two ecologically distinct ranges

ABSTRACT Underlying biological processes can often shape phenotypic variation. Although subtle, the variation in plumage colour of the Azure Jay (Cyanocorax caeruleus) has long been suggested to be of phylogeographic importance, but this hypothesis was not tested. This species’ distribution in the Atlantic Forest biome of south-eastern Brazil is divided into two ecologically distinct portions by the Serra do Mar mountain line. The availability of Parana Pine (Araucaria angustifolia) seeds is essential for the survival of Azure Jays in the western range but not in the eastern range. Here we quantify Azure Jay geographic variation using three datasets, including vocalisations, morphology and plumage colour. All available data independently supported the hypothesis of divergence between east and west. Azure Jays in the western range tend to have: (1) larger body dimensions, (2) vocalisations with lower pitch and entropy, and (3) a greenish-blue plumage, than those in the eastern range. Based on the available data on this species’ ecology, life history and sociality, we discuss how features from the western range could indicate specialisation in habitat use. We discuss potential links between our results and the past of the Atlantic Forest and the implications for this species conservation in a highly threatened habitat. Finally, we highlight the pressing need for demographic and molecular evidence to make data-oriented and effective decisions for this species conservation.

Does spring bring colors? Seasonal bird plumage color variation along urban-rural gradients

Urbanization alters the landscape through the replacement of natural vegetation by impervious surfaces, probably inducing changes in interspecific bird color diversity and composition. However, the seasonal changes of bird color diversity and composition along urban-rural gradients have not been analyzed yet. The objective of this study was to analyze the seasonal variation of bird color diversity and composition of bird assemblages along urban-rural gradients of three cities in central Argentina. Bird surveys were made in urban, suburban and rural areas during the breeding and non-breeding seasons. Color description was obtained from the literature. Color diversity and the seasonal color dissimilarity were calculated using the mean pairwise distance functional index. Null models that control for species richness were used to estimate standardized effect sizes (SES). Color diversity increased during the breeding season. However, the SES of color diversity did not change between seasons. Color diversity and the SES of color diversity were higher in rural areas than in urban habitats. The color seasonal dissimilarity was the lowest in urban habitats. City size was negatively related to the color seasonal dissimilarity in urban and suburban habitats. Species with brown, black and dimorphic plumages showed seasonal changes in their abundances in rural habitats, whereas plumage colors in urban habitats remained stable between seasons. The results showed that bird color diversity increase during the breeding season, but this increase is related to the arrival of more species during the breeding season to rural areas. Urban areas showed a seasonal homogenization of bird colors.

New insights into genetics underlying of plumage color

Plumage color can be considered as a social signal in chickens and a breeding identification tool among breeders. The relationship between plumage color and trait groups of immunity, growth and fertility is still a controversial issue. This research aimed to determine the genome-wide additive and epistatic variants affecting plumage color variation in chickens using the chicken Illumina 60k high-density SNP array. Two scenarios of genome-wide additive association studies using all SNPs and independent SNPs were carried out. To perform epistatic association analysis, the LD pruning approach was used to reduce the complexity of the analysis. We detected seven novel significant loci using all of the SNPs in the model and 14 SNPs using the LD pruning approach associated with plumage color. Moreover, 89 significantly associated SNP-SNP interactions (P-value <10-6 ) distributed in 25 chromosomes were identified, indicating that all of the signals together putatively influence the quantitative variation of plumage color. By annotating genes relevant to top SNPs, we have distinguished 18 potential candidate genes comprising HNF4beta, CKMT1B, TBC1D22A, RPL8, CACNA2D1, FZD4, SGMS1, IRF8, OPTN, LOC420362, TRABD, OvoDA1, DAD1, USP6, RBM12B, MIR1772, MIR1709 and MIR6696 and also 89 putative gene-gene combinations responsible for plumage color variation in chickens. Furthermore, several KEGG pathways including metabolic pathway, cytokine-cytokine receptor interaction, focal adhesion, melanogenesis, glycosaminoglycan biosynthesis-keratan sulfate and sphingolipid metabolism were enriched in the gene-set analysis. The results indicated that plumage color is a highly polygenic trait which, in turn, can be affected by multiple coding genes, regulatory genes and gene-gene epistasis interactions. In addition to genes with additive effects, epistatic genes with tiny individual effect sizes but significant effects in a pair have the potential to control plumage coloration in chickens.

Variation in Genetic Mechanisms for Plumage Polymorphism in Skuas (Stercorarius).

Coloration is evolutionarily labile and so provides an excellent trait for examining the repeatability of evolution. Here, we investigate the repeatability of the evolution of polymorphic variation in ventral plumage coloration in skuas (Stercorarius: Stercorariidae). In 2 species, arctic (S. parasiticus) and pomarine skuas (S. pomarinus), plumage polymorphism was previously shown to be associated with coding changes at the melanocortin-1 receptor (MC1R) locus. Here, we show that polymorphism in a third species, the south polar skua (S. maccormicki), is not associated with coding variation at MC1R or with variation at a Z-linked second candidate locus, tyrosinase-related protein 1 (TYRP1). Hence, convergent evolution of plumage polymorphisms in skuas is only partly repeatable at the level of the genetic locus involved. Interestingly, the pattern of repeatability in skuas is aligned not with phylogeny but with the nature of the phenotypic variation. In particular, south polar skuas show a strong sex bias to coloration that is absent in the other species, and it may be that this has a unique genetic architecture.

Polly Wants a Genome: The Lack of Genetic Testing for Pet Parrot Species.

Parrots are considered the third most popular pet species, after dogs and cats, in the United States of America. Popular birds include budgerigars, lovebirds and cockatiels and are known for their plumage and vocal learning abilities. Plumage colour variation remains the main driving force behind breeder selection. Despite the birds’ popularity, only two molecular genetic tests—bird sexing and pathogen screening—are commercially available to breeders. For a limited number of species, parentage verification tests are available, but are mainly used in conservation and not for breeding purposes. No plumage colour genotyping test is available for any of the species. Due to the fact that there isn’t any commercial plumage genotype screening or parentage verification tests available, breeders mate close relatives to ensure recessive colour alleles are passed to the next generation. This, in turn, leads to inbreeding depression and decreased fertility, lower hatchability and smaller clutch sizes, all important traits in commercial breeding systems. This review highlights the research carried out in the field of pet parrot genomics and points out the areas where future research can make a vital contribution to understanding how parrot breeding can be improved to breed healthy, genetically diverse birds.

Geographic variation in body size and plumage colour according to diet composition in a nocturnal raptor

Predator–prey interactions are amongst the strongest selective forces that promote the evolution of local phenotypes in both predators and prey. However, intraspecific spatial covariation in phenotypic traits between predators and prey has been rarely investigated, especially at a large geographic scale. Here, we studied the covariation between prey composition and some phenotypic traits, such as wing length, bill length and plumage colour, of a widely‐distributed nocturnal predator, the western barn owl Tyto alba. By using 3100 specimens collected across its entire range of distribution, spanning from Europe to Middle East and Africa, we showed that wing length positively covaries with prey size, but not with taxonomic composition. This finding suggests that larger prey might have selected for larger body size and/or that larger individuals might be more selective in hunting large prey. In addition, we also found that paler‐plumaged populations generally hunt larger prey. Paler barn owls might be thus better specialized in capturing averagely larger prey and/or mainly hunt in habitats where larger prey are more abundant. In addition, considering that paler individuals are generally larger than brownish ones, it is possible that paler plumage colour might have evolved as a by‐product of selection towards a large body size, which in turn have emerged in response to prey size composition. However, irrespectively of the direction of causality and the phenotypic target of selection, we showed that predator–prey interactions can affect spatial phenotypic variation by promoting the evolution of local adaptations.

Is color data from citizen science photographs reliable for biodiversity research?

Color research continuously demands better methods and larger sample sizes. Citizen science (CS) projects are producing an ever‐growing geo‐ and time‐referenced set of photographs of organisms. These datasets have the potential to make a huge contribution to color research, but the reliability of these data need to be tested before widespread implementation.We compared the difference between color extracted from CS photographs with that of color extracted from controlled lighting conditions (i.e., the current gold standard in spectrometry) for both birds and plants. First, we tested the ability of CS photographs to quantify interspecific variability by assessing > 9,000 CS photographs of 537 Australian bird species with controlled museum spectrometry data. Second, we tested the ability of CS photographs to quantify intraspecific variability by measuring petal color data for two plant species using seven methods/sources with varying levels of control.For interspecific questions, we found that by averaging out variability through a large sample size, CS photographs capture a large proportion of across species variation in plumage color within the visual part of the spectrum (R2 = 0.68–0.71 for RGB space and 0.72–0.77 for CIE‐LAB space). Between 12 and 14 photographs per species are necessary to achieve this averaging effect for interspecific studies. Unsurprisingly, the CS photographs taken with commercial cameras failed to capture information in the UV part of the spectrum. For intraspecific questions, decreasing levels of control increase the color variation but averaging larger sample sizes can partially mitigate this, aside from particular issues related to saturation and irregularities in light capture.CS photographs offer a very large sample size across space and time which offers statistical power for many color research questions. This study shows that CS photographs contain data that lines up closely with controlled measurements within the visual spectrum if the sample size is large enough, highlighting the potential of CS photographs for both interspecific and intraspecific ecological or biological questions. With regard to analyzing color in CS photographs, we suggest, as a starting point, to measure multiple random points within the ROI of each photograph for both patterned and unpatterned patches and approach the recommended sample size of 12–14 photographs per species for interspecific studies. Overall, this study provides groundwork in analyzing the reliability of a novel method, which can propel the field of studying color forward.

Rapid speciation via the evolution of pre-mating isolation in the Iberá Seedeater.

Behavioral isolation can catalyze speciation and permit the slow accumulation of additional reproductive barriers between co-occurring organisms. We illustrate how this process occurs by examining the genomic and behavioral bases of pre-mating isolation between two bird species (Sporophila hypoxantha and the recently discovered S. iberaensis) that belong to the southern capuchino seedeaters, a recent, rapid radiation characterized by variation in male plumage coloration and song. Although these two species co-occur without obvious ecological barriers to reproduction, we document behaviors indicating species recognition by song and plumage traits and strong assortative mating associated with genomic regions underlying male plumage patterning. Plumage differentiation likely originated through the reassembly of standing genetic variation, indicating how novel sexual signals may quickly arise and maintain species boundaries.

Phylogeography and morphometric variation of the Spike-heeled Lark Chersomanes albofasciata complex

The Spike-heeled Lark Chersomanes albofasciata is a peculiar, short-tailed lark confined to southern, central and East Africa. Typical of resident larks, it exhibits marked geographic variation in plumage colour, which has historically resulted in large numbers of subspecies being described. This variation was examined by sequencing 630 base pairs of the cytochrome b gene in 39 individuals and morphometric measurements of 320 birds. Nine of the 14 southern African C. albofasciata subspecies defined by Clancey in 1980 were sampled for assessing genetic variation, as well as one population from northern Namibia (C. a. boweni) and the isolated C. [a.] beesleyi population in Tanzania. Within South Africa, 16 maternal lineages were identified. The haplotype network revealed three geographically distinct haplogroups: Namaqualand, Karoo and Eastern grasslands, which did not follow past or existing subspecies ranges. Our data thus suggest incongruence between genetic variation and phenotype in South Africa. The boundaries and relationship among the phylogeographic haplogroups and morphometric measurement were similar to the closely related Long-billed Lark Certhilauda curvirostris complex suggesting similar processes during their evolutionary history. The existing subspecies designations are clearly not supported by the genetic data presented here and thus more research into this complex is required. Further research should include sampling of Spike-heeled Larks in underrepresented areas of the species’ range and the use of additional genetic markers to improve our understanding of the evolutionary history of this complex. C. [a.] beesleyi was sister to all haplotypes sampled and smaller in size than all subspecies measured. Although the status of the contentious C. [a.] beesleyi has still not been resolved, we have added morphometric data supporting its isolation from other subspecies. Its limited and isolated range warrants increased conservation efforts and we propose its recognition as an evolutionarily significant unit.

Adaptive coloration in pied flycatchers (Ficedula hypoleuca)-The devil is in the detail.

Understanding the origin and persistence of phenotypic variation within and among populations is a major goal in evolutionary biology. However, the eagerness to find unadulterated explanatory models in combination with difficulties in publishing replicated studies may lead to severe underestimations of the complexity of selection patterns acting in nature. One striking example is variation in plumage coloration in birds, where the default adaptive explanation often is that brightly colored individuals signal superior quality across environmental conditions and therefore always should be favored by directional mate choice. Here, we review studies on the proximate determination and adaptive function of coloration traits in male pied flycatchers (Ficedula hypoleuca). From numerous studies, we can conclude that the dark male color phenotype is adapted to a typical northern climate and functions as a dominance signal in male–male competition over nesting sites, and that the browner phenotypes are favored by relaxed intraspecific competition with more dominant male collared flycatchers (Ficedula albicollis) in areas where the two species co‐occur. However, the role of avoidance of hybridization in driving character displacement in plumage between these two species may not be as important as initially thought. The direction of female choice on male coloration in pied flycatchers is not simply as opposite in direction in sympatry and allopatry as traditionally expected, but varies also in relation to additional contexts such as climate variation. While some of the heterogeneity in the observed relationships between coloration and fitness probably indicate type 1 errors, we strongly argue that environmental heterogeneity and context‐dependent selection play important roles in explaining plumage color variation in this species, which probably also is the case in many other species studied in less detail.