Chromosome-level assembly of the genome of the Aythya nyroca provides insights into diving adaptations.

BACKGROUND

Aythya nyroca (Ferruginous Duck), a small to medium-sized chestnut-colored diving duck, is mainly distributed in central, western, and southern Asia, southern Europe, and central Africa. We employed Oxford Nanopore sequencing and Hi-C technique to assemble the first chromosome-level genome of A. nyroca. The assembled genome had a scaffold N50 of 86,001,877 bp, with 35 pseudochromosomes mounted. Repeat sequences accounted for approximately 14.84 % of the genome.

RESULTS

To uncover the molecular mechanisms of diving adaptations in A. nyroca, we conducted separate enrichment analyses on species-unique genes, expanded and contracted gene families, and positively selected genes. The results indicated the enrichment of pathways related to blood oxygen concentration regulation and energy metabolism. The enrichment of related pathways and the positive selection of related genes may reveal the adaptive evolutionary mechanism of A. nyroca in the diving environment.

CONCLUSIONS

This high-quality genome provides a valuable resource for studying the evolution of the diving adaptation mechanism in birds. Whole-genome assemblies are crucial for comprehensively understanding various aspects of A. nyroca biology, including morphology, ecology, and physiology, and thus play an essential role in its conservation.