We studied morphological differentiation in the flight apparatus of the four currently recognised sub-species of Northern Wheatears, Oenanthe oenanthe. Considering all measured birds without assigning them a priori to any sub-species we found a clinal morphological shift. Relative wing length, wing pointedness, and the degree of tail forking were positively correlated with migratory distance, whereas tail length (relative to wing length) was negatively correlated. The large-sized, long-distance migrant “Greenland” Wheatear, O. o. leucorhoa, is characterized by relatively longer, broader and more pointed wings and more forked tails, similar to the smaller-sized nominate Northern Wheatear, O. o. oenanthe, from North Europe, Siberia and Russia. In contrast, the short distance migrant “Seebohm's” Wheatear, O. o. seebohmi, from northwest Africa, possesses much rounder wings, and the tail is relatively longer and less forked. Sub-species with intermediate migratory habits (different populations of nominate Northern Wheatear, O. o. oenanthe, and “Mediterranean” Northern Wheatear, O. o. libanotica) show, as expected, intermediate features according to their intermediate migratory behaviour. Our results are congruent with other inter- and intraspecific studies finding similar adaptations for energy-effective flight in relation to migration distance (morphological migratory syndrome).

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Summary 1.Condition-dependent expression of ornamental traits is a fundamental assumption of theories on the honesty of sexual signals, and it is widely assumed that condition-dependence is a signature feature of ornaments. 2. Some of the best understood condition-dependent traits are the striking carotenoid-based plumage signals of male birds, yet little is known about the many less conspicuous, less elaborate carotenoid-based plumage colours that often comprise large parts of the plumage. 3. We examined colour (reflectance) of carotenoid-based plumage in male greenfinches that were provided with naturalistic diets with relatively low and with enhanced lutein availability during their annual moult. Using a variety of objective colorimetrics, including physiological models of avian colour vision, we compared experimental effects and general condition-dependence on the contrasting bright yellow tail patch, the yellow-green breast as well as three duller, yellow-to olive-green patches (back, crown, rump). 4. Irrespective of the analysis method used, we found consistent and large diet effects on the reflectance of the tail, much weaker effects on the reflectance of the breast, and no significant effects on the other three plumage parts. Likewise, we found that only the colour of the tail was strongly associated with circulating (plasma) lutein concentration, as well as with general condition (body mass, haematocrit). 5. Our results suggest that, in accord with current theories on the signal honesty, the striking yellow tail patch of the male greenfinch appears to be particularly well-adapted to signal information on carotenoid availability and general condition of the male during moult.

Genetic and phenotypic mosaics, in which various phenotypes and different genomic regions show discordant patterns of species or population divergence, offer unique opportunities to study the role of ancestral and introgressed genetic variation in phenotypic evolution. Here, we investigated the evolution of discordant phenotypic and genetic divergence in a monophyletic clade of four songbird taxa—pied wheatear (O. pleschanka), Cyprus wheatear (Oenanthe cypriaca), and western and eastern subspecies of black‐eared wheatear (O. h. hispanica and O. h. melanoleuca). Phenotypically, black back and neck sides distinguish pied and Cyprus wheatears from the white‐backed/necked black‐eared wheatears. Meanwhile, mitochondrial variation only distinguishes western black‐eared wheatear. In the absence of nuclear genetic data, and given frequent hybridization among eastern black‐eared and pied wheatear, it remains unclear whether introgression is responsible for discordance between mitochondrial divergence patterns and phenotypic similarities, or whether plumage coloration evolved in parallel. Multispecies coalescent analyses of about 20,000 SNPs obtained from RAD data mapped to a draft genome assembly resolve the species tree, provide evidence for the parallel evolution of colour phenotypes and establish western and eastern black‐eared wheatears as independent taxa that should be recognized as full species. The presence of the entire admixture spectrum in the Iranian hybrid zone and the detection of footprints of introgression from pied into eastern black‐eared wheatear beyond the hybrid zone despite strong geographic structure of ancestry proportions furthermore suggest a potential role for introgression in parallel plumage colour evolution. Our results support the importance of standing heterospecific and/or ancestral variation in phenotypic evolution.

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The insular endemic Cyprus Wheatear Oenanthe cypriaca has been considered as a subspecies of Pied Wheatear O. pleschanka. However, due to several differences in behaviour, habitat selection and morphology, it is currently treated by most authors as an independent species. Here, we used mitochondrial nucleotide sequences of the cytochrome oxidase subunit 1 gene (679 base pairs), playback experiments and dummy presentations to assess the status of O. cypriaca. For the playback experiments we used the conspecific song, and heterospecific songs of the two subspecies of Black-eared Wheatear O. hispanica hispanica and O. hispanica melanoleuca, O. pleschanka, and Finsch's Wheatear O. finschii. Experimental dummy presentations included O. cypriaca, O. pleschanka and a dark and light morph of O. h. melanoleuca. O. cypriaca responded significantly stronger towards the conspecific model and towards conspecific playbacks than towards heterospecific stimuli. ML and BI analyses support the close relationship between O. cypriaca, O. pleschanka and O. h. melanoleuca. With a relative high posterior probability value (0.98), O. cypriaca clusters closer to O. h. melanoleuca from Iran and Israel (on migration) and O. pleschanka from Iran than to O. pleschanka obtained from Kazakhstan, Russia, Mongolia and wintering areas in East Africa (Kenya). The scenario suggests that O. cypriaca might be either a relatively young taxon, which is yet behavioural distinct, but genetically still similar to its sister populations on the mainland. Alternatively, we may assume a close relationship as an indication for potential ongoing hybridisation processes involving all three forms.

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