Draft Genome of the Mirrorwing Flyingfish (Hirundichthys speculiger)

Abstract

Flying fishes are a group of Exocoetidae members with an intriguing epipelagic inhabitant. They have evolved numerous interesting characteristics. Here, we performed whole genome sequencing, de novo assembly and annotation of the representative mirrorwing flyingfish (Hirundichthys speculiger). We obtained a 1.04-Gb genome assembly using a hybrid approach from 99.21-Gb Illumina and 29.98-Gb PacBio sequencing reads. Its contig N50 and scaffold N50 values reached 992.83 and 1,152.47 kb, respectively. The assembled genome was predicted to possess 23,611 protein-coding genes, of which 23,492 (99.5%) were functionally annotated with public databases. A total of 42.02% genome sequences consisted of repeat elements, among them DNA transposons accounted for the largest proportion (24.38%). A BUSCO (Benchmarking Universal Single Copy Orthologs) evaluation demonstrated that the genome and gene completeness were 94.2% and 95.7%, respectively. Our phylogeny tree revealed that the mirrorwing flyingfish was close to Oryzias species with a divergence time of about 85.2 million years ago. Moreover, nine vison-related genes, three melatonin biosynthesis related aanat (aralkylamine N-acetyltransferase) genes, and two sunscreen biosynthesis related eevs (2-epi-5-epi-valiolone synthase) genes were identified in the assembled genome; however, the loss of SWS1 (short-wavelength sensitive opsin 1) and aanat1a in amphibious mudskippers was not presented in the mirrorwing flyingfish genome. In summary, we generate a high-quality draft genome assembly for the mirrorwing flyingfish, which provides new insights into physiology-related genes of Exocoetidae. It also serves as a powerful resource for exploring intriguing traits of Exocoetidae at a genomics level.

Literature Review of Flying Fish: Biology, Distribution, Flying Fish Fisheries, and Current Research

“…Once in the air, flying fish will expand their broad pectoral fins to stay afloat for a long time. When crossing the surface of the waters to fly flying fish face various challenges such as continuous sunlight, lack of buoyancy and high accumulation of CO2 (Wright and Turko 2016) as amphibian fish (Xu et al 2021). The refractive index of air usually affects fish to be myopic in air (Baylor and Shaw 1962).…”