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Background Feathers with complex and fine structure are hallmark avian integument appendages, which have contributed significantly to the survival and breeding for birds. Here, we aimed to explore the differentiation, morphogenesis and development of diverse feathers in the domestic duck. Results Transcriptome profiles of skin owing feather follicle from two body parts at three physiological stages were constructed to understand the molecular network and excavate the candidate genes associated with the development of plumulaceous and flight feather structures. The venn analysis of differentially expressed genes (DEGs) between abdomen and wing skin tissues at three developmental stages showed that 38 genes owing identical differentially expression pattern. Together, our data suggest that feather morphological and structural diversity can be possibly related to the homeobox proteins. The key series-clusters, many candidate biological processes and genes were identified for the morphogenesis, growth and development of two feather types. Through comparing the results of developmental transcriptomes from plumulaceous and flight feather, we found that DEGs belonging to the family of WNT, FGF and BMP have certain differences; even the consistent DEGs of skin and feather follicle transcriptomes from abdomen and wing have the different expression patterns. Conclusions Overall, this study detected many functional genes and showed differences in the molecular mechanisms of diverse feather developments. The findings in WNT, FGF and BMP, which were consistent with biological experiments, showed more possible complex modulations. A correlative role of HOX genes was also suggested but future biological verification experiments are required. This work provided valuable information for subsequent research on the morphogenesis of feathers.

Plumology is being used in a variety of avian research fields such as from ecology and evolution to prey-predator relationship. However, very few systematic studies have been conducted in India using plumology. The paper compares macro- and micro-structural feathers’ features from four species of family Columbidae viz. the Spotted dove ( Spilopelia chinensis ), Grey-fronted green pigeon ( Treron affinis ), Eurasian collared dove ( Streptopelia decaocto ) and Common pigeon ( Columba livia ) from different Indian localities. A morphometric analysis of the downy and contour feathers’ structures of the listed species was carried out. Since the feathers were taken from significantly damaged carcasses, it was necessary to determine the pterylae of the flying feathers to which the latter belong. Morphometric features of feathers viz. calamus, rachis, vane and mounted barb length were measured. An atypical for Columbidae feature presence of villi has been observed but only for T. affinis species . The presence of typical pigmented quadrilobed nodes was noted in all Columbidae species. Pigmented and non-pigmented plain pronged nodes and plain swollen nodes were observed. The presence of three different nodes on barbules and nodes’ pigmentation may be considered as key taxonomic characteristics for studied Columbidae species. The feather comparison method made it possible to identify pterylae of studied feathers.

We examined variation in five microscopic plumulaceous (downy) feather characters of eighteen species of dabbling (Anatini) and diving (Aythyini, Mergini) ducks to quantify the differences between these tribes, and to explain how the plumulaceous feather ultrastructure in ducks may be influenced by different ecological requirements. Over 75% of the variation in feather characters among these ducks was explained by the first two components of a principal components analysis (PCA). Component 1 explained 51% of the variation and was positively correlated with the characters that quantified the number of barbules with expanded nodes and the number of expanded nodes on barbules. The microscopic feather characters of dabbling ducks (Anatini) have triangular-shaped, expanded nodes on most proximal barbules, whereas diving ducks (Aythyini and Mergini) lack expanded nodes on some barbules. Anatini also have a greater density of expanded nodes per barbule, wider nodes, shorter distance between expanded nodes, and longer barbule length. Further analysis of node density across all taxa showed that as dive depths increase, the number of expanded nodes per barbule decreases, and in the deepest divers many of the barbules completely lack expanded nodes. The significantly greater density of expanded nodes in dabbling ducks suggests that the downy nodes may function to trap more air. Diving species have fewer expanded nodes, less buoyant plumage, and are more efficient at foraging in deeper water than dabbling ducks.

Variation in microscopic characters of plumulaceous barbs of six species of Charadrius was studied to quantify characters and test differences among taxa. Pluvialis squatarola was used for intergeneric comparisons. Intraspecific variation in feathers from the sternopectoral tract of C. vociferus was examined to define character parameters and to determine within-vane variation and vane symmetry. A significant difference was observed among the barbs of four regions within each vane of the same feather, but barbs from opposing vanes were not significantly different from one another. Interspecific variation then was studied using discriminant function analysis. Pluvialis separated from all species of Charadrius. Two subgroups were apparent within Charadrius: semipalmatus, vociferus and montanus separated from wilsonia, alexandrinus and melodus.