The complete mitochondrial genome sequence of an Endangered powerful owl (Ninox strenua)

Abstract

In this paper, the complete mitochondrial genome of an Endangered Ninox strenua is sequenced and reported for the first time. The mitogenome of N. strenua is a circular molecule of 16,206 bp in length, consisting of 13 protein-coding genes (PCGs), 22 tRNA, 2 rRNA, and a control region (D-loop). All the genes in N. strenua are distributed on the H-strand, except for the ND6 subunit gene and eight tRNA genes, which are encoded on the L-strand. Phylogenetic analysis using an available mitogenome of Strigidae family revealed a close evolutionary relationship of N. strenua with N. novaeseelandiae, a Tasmanian spotted owl found throughout the Australasia.

The avian order Strigiformes represents an intriguing model, which occupies the ecological niche of nocturnal raptor (Wink et al. 2009). Owls are birds from the order Strigiformes which includes about 200 species. Powerful owl (Ninox strenua), a member of the family Strigidae (order Strigiformes), is one of the largest and endemic Australian owl species (Ian & Dariel 2005). The Powerful owl is currently listed as Vulnerable or threatened in Queensland, New South Wales, and Victoria, whereas the species has been listed as Endangered in South Australia under the National Parks and Wildlife Act 1972 (NPW Act). The systematic position of the family Strigidae has been studied using morphological, and molecular characters’ dependent on the Cytochrome b and the Nuclear RAG-1 genes (Wink et al. 2009). A well-resolved avian phylogenetic tree is required for understanding biogeographic evolutionary structure, whilst there are still major uncertainties in the position of many avian species due to a lack of abundant mitochondrial (mt) data sets. Complete mitogenomes could play a vital role to understand the origin, evolution, and divergence time of speciation (Bagatharia et al. 2013), as well as influencing conservation and management decisions (Eo et al. 2010). In the present study, we report a complete mitogenome of Ninox strenua in order to provide further insights into the biology, host phylogeny, and conservation of the species.

The blood sample was obtained from a powerful owl in the wild (year of sampling: 2015; GPS location: 34°00′22.9″S, 151°02′18.6″E). The sample was immediately transferred to the Veterinary Diagnostic Laboratory (VDL), Charles Sturt University, and stored under the accession number CS15-3907. Animal sampling was obtained in accordance with approved guidelines set by the Australian Code of Practice for the Care and Use of Animals for Scientific Purposes (1997) and approved by the Charles Sturt University Animal Ethics Committee (Research Authority permit 09/046). The total genomic DNA was extracted using an established protocol (Sarker et al. 2016). The genomic libraries were prepared with an insert size of 150 paired-end. The next-generation sequencing (NGS) was performed on a HiSeq2500 sequencing platform (Illumina) at the Novogene, China, and generated approximately 11.9 million sequence reads from the genomic DNA of the Powerful owl. The sequences were assembled, and the construction of contigs with a minimum average PHRED score of 25 was considered in CLC Genomics workbench 9.0.1 under La Trobe University Genomics Platform.

The complete mitochondrial genome sequence of N. strenua was 16,206 bp in length (GenBank accession no. KX529654) with a 47.2% GC content. It encodes 37 genes containing 13 PCGs, 22 tRNA genes, 2 rRNA genes, and a control region. Among these, 9 genes are encoded on the L-strand, including ND6 and 8 tRNA genes (tRNA^Gln, tRNA^Ala, tRNA^Asn, tRNA^Cys, tRNA^Tyr, tRNA^Ser, tRNA^Pro, and tRNA^Glu), the remaining 28 genes are encoded on the H-strand. The gene arrangement is similar to the complete mitochondrial genome of other Strigidae species.

The complete mitochondrial genome sequences relevant to the family Strigidae available in GenBank was aligned using the MAFFT L-INS-i algorithm (Katoh et al. 2002), and the neighbour-joining (NJ) tree with 1000 nonparametric bootstrap resamplings were generated using CLC Genomics workbench 9.0.1. The phylogenetic tree revealed that N. strenua was clustered most closely to N. novaeseelandiae, Tasmanian spotted owl which is found throughout Tasmania and New Zealand (Figure 1), and is consistent with previous research (Wink et al. 2009). We expect the complete mitogenome of N. strenua will be a useful database for further research and host-phylogenetic analysis of Strigidae species, and their implication for the conservation of the species.

Figure 1.

Host-phylogenetic inference of evolutionary relationship among Strigidae family. NJ-tree was constructed using complete mitochondrial genome sequences of species belonging to the Strigidae family, and a Black-capped kingfisher (Halcyon pileata; GenBank accession: KJ476742) as an outgroup.