Transcriptome Comparison Reveals Key Components of Nuptial Plumage Coloration in Crested Ibis

A Breeding Plumage in the Making: The Unique Process of Plumage Coloration in the Crested Ibis in Terms of Chemical Composition and Sex Hormones

The Crested Ibis (Nipponia nippon) has long fascinated ornithologists with its enigmatic plumage color change. After more than a century of curiosity, the mystery was finally unraveled in the 1970s, unveiling the mechanism behind this remarkable transformation. Unlike other bird species, the Crested Ibis achieves its nuptial plumage coloration through a unique daubing behavior. After a water-bathing, it applies a sticky black substance secreted by a patch of skin in the neck and throat region. However, the chemical components of this black substance have not been studied in detail until now. To address this issue, we conducted a study to detect the components of the black substance and explore the relationship between sex hormone levels and the secretion of the black substance. We used enzyme-linked immunosorbent assay (ELISA) to measure the monthly changes in steroid hormone levels (estradiol E2, testosterone T, and progesterone PROG) levels in feces. We also analyzed the correlation between sex hormone levels and daubing behavior. The results showed that the sex hormone levels are closely related to the secretion and application of the black substance. In addition, we qualitatively analyzed the chemical components of the black substance using gas chromatography-mass spectrometry (GC-MS), uncovering the presence of 117 distinct chemical components. We assume that the black coloration results from the polymerization of selected chemical constituents among these components. These findings provide a groundwork for further exploration into the biological significance of the black substance. Overall, our study detected components in the black substance and studied how sex hormone levels relate to its secretion. Understanding the hormone effects on coloration helps in precise habitat management, like wetland preservation, crucial for Crested Ibis survival. Implementing hormone-boosting measures during breeding seasons enhances reproduction and health, vital for their conservation.

The draft genome of the Temminck's tragopan (Tragopan temminckii) with evolutionary implications

BACKGROUND

High-quality genome data of birds play a significant role in the systematic study of their origin and adaptive evolution. The Temminck's tragopan (Tragopan temminckii) (Galliformes, Phasianidae), a larger pheasant, is one of the most abundant and widely distributed species of the genus Tragopan, and was defined as class II of the list of national key protected wild animals in China. The absence of a sequenced genome has restricted previous evolutionary trait studies of this taxa.

RESULTS

The whole genome of the Temminck's tragopan was sequenced using Illumina and PacBio platform, and then de novo assembled and annotated. The genome size was 1.06 Gb, with a contig N50 of 4.17 Mb. A total of 117.22 Mb (11.00%) repeat sequences were identified. 16,414 genes were predicted using three methods, with 16,099 (98.08%) annotated as functional genes based on five databases. In addition, comparative genome analyses were conducted across 12 Galliformes species. The results indicated that T. temminckii was the first species to branch off from the clade containing Lophura nycthemera, Phasianus colchicus, Chrysolophus pictus, Syrmaticus mikado, Perdix hodgsoniae, and Meleagris gallopavo, with a corresponding divergence time of 31.43 million years ago (MYA). Expanded gene families associated with immune response and energy metabolism were identified. Genes and pathways associated with plumage color and feather development, immune response, and energy metabolism were found in the list of positively selected genes (PSGs).

CONCLUSIONS

A genome draft of the Temminck's tragopan was reported, genome feature and comparative genome analysis were described, and genes and pathways related to plumage color and feather development, immune response, and energy metabolism were identified. The genomic data of the Temminck's tragopan considerably contribute to the genome evolution and phylogeny of the genus Tragopan and the whole Galliformes species underlying ecological adaptation strategies.