Whole Genome Sequencing of the Asian Arowana (Scleropages formosus) and Future Prospects for Arowana Genetic Research

The Asian arowana (Scleropages formosus) is of commercial importance, conservation concern and is a representative of one of the most ancient basal teleosts, the Osteoglossomorpha. To add to genomic knowledge of this species and the evolution of teleosts, the genome of a specimen of Malaysian arowana was sequenced. A draft genome is presented consisting of 42,120 scaffolds with a total size of 708 Mb. Using a k-mer based method, a genome size of 900 Mb was also estimated. Sequencing depth is approximately 58× coverage with 93.95% of core eukaryotic genes (CEGs) represented.

We present an update on the phylogeny of fishes based genomic information using 23 fish species and selected tetrapods based on 295 orthologous proteins, which supports established relationships except that arowana is placed at the most basal position rather than the eel species for the teleost clades that evolved after the teleost genome duplication (TGD) event. Evolutionary rates are highly heterogeneous across the tree with fish represented by both slowly- and rapidly-evolving species. A total of 79 putative pigment genes were identified, which will be a valuable resource to understanding the basis for the spectacular coloured phenotypes found within this species.

Prospects for future molecular genetic research on arowana focussing on molecular taxonomy, population genetics and broodstock management for the ornamental industry are discussed.