Research Article |
Corresponding author: Wenjuan Shan ( wenjuanshan@sina.com ) Academic editor: Pavel Stoev
© 2021 Wenjuan Shan, Mayinur Tursun, Shiyu Zhou, Yucong Zhang, Huiying Dai.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Shan W, Tursun M, Zhou S, Zhang Y, Dai H (2021) Complete mitochondrial genome sequence of Lepus yarkandensis Günther, 1875 (Lagomorpha, Leporidae): characterization and phylogenetic analysis. ZooKeys 1012: 135-150. https://doi.org/10.3897/zookeys.1012.59035
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Lepus yarkandensis is a national second-class protected animal endemic to China and distributed only in the hot and arid Tarim Basin in Xinjiang. We sequenced and described the complete mitogenome of L. yarkandensis to analyze its characteristics and phylogeny. The species’ DNA is a 17,047 bp circular molecule that includes 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes, and one control region. The overall base composition was as follows: A, 31.50%; T, 29.40%; G, 13.30% and C, 25.80%, with a high A+T bias of 60.9%. In the PCGs, ND6 had deviation ranges for AT skew (–0.303) and GC skew (0.636). The Ka/Ks values of ND1 (1.067) and ND6 (1.352) genes were >1, indicating positive selection, which might play an important role in the adaptation of L. yarkandensis to arid and hot environments. The conserved sequence block, the central conserved domain, and the extended termination-associated sequences of the control region and their features were identified and described. The phylogenetic tree based on the complete mitogenome showed that L. yarkandensis was closely related to the sympatric Lepus tibetanus pamirensis. These novel datasets of L. yarkandensis can supply basic data for phylogenetic studies of Lepus spp., apart from providing essential and important resource for further genetic research and the protection of this species.
mitogenome, molecular phylogeny, synonymous/non-synonymous substitution, Yarkand hare
The Yarkand hare (Lepus yarkandensis) is endemic to China and is restricted to scattered oases around the Taklamakan Desert in the Tarim Basin of Xinjiang (
Characterized by small size, stable gene content, high evolutionary rate, relatively conserved gene arrangement, high information content, and maternal inheritance, animal mitogenomes are powerful tools used to investigate molecular evolution, phylogenetic relationships, and protective biology for many animals (
In the present study, we successfully sequenced and characterized the complete mtDNA of L. yarkandensis, including its base composition, gene structure, and arrangement of protein-coding genes (PCGs) and a control region. We also constructed a phylogenetic tree based on complete mitogenome sequences to elucidate the relationship of L. yarkandensis with other Lepus spp. Therefore, this study provides essential scientific data and contributes to population genetics, adaptation, and phylogenetic studies of L. yarkandensis.
A male adult L. yarkandensis was collected from Alar, Xinjiang, China (40°34'00"N, 81°19'33"E) on 24 December 2016. Complete mtDNA was extracted from muscle tissue using standard phenol-chloroform (
Lagomorph mitogenomes used in the phylogenetic analysis of the present study.
Name | Accession number | Collection places | Size |
---|---|---|---|
Lepus americanus1 | NC024043 | Montana, USA | 17042 |
Lepus americanus2 | KJ397613 | Montana, USA | 17042 |
Lepus capensis | GU937113 | Yancheng, Jiangsu | 17722 |
Lepus coreanus | KF040450 | Incheon, Korea | 17472 |
Lepus europaeus1 | AJ421471 | Skane, Sweden | 17734 |
Lepus europaeus2 | KY211025 | North-east Greece | 16680 |
Lepus granatensis1 | NC024042 | León, Spain | 16916 |
Lepus granatensis2 | KJ397610 | León, Spain | 16916 |
Lepus hainanus | JQ219662 | Hainan, China | 16646 |
Lepus sinensis | KM362831 | Hefei Anhui | 17438 |
Lepus tibetanus pamirensis | LC073697 | Aketao, Xinjiang, | 17597 |
Lepus timidus1 | KR019013 | Haerbin, Heilongjiang | 17762 |
Lepus timidus2 | KJ397605 | Finland | 17755 |
Lepus timidus3 | KR030070 | Harbin, Heilongjiang | 17748 |
Lepus timidus4 | KR030072 | Harbin, Heilongjiang | 17749 |
Lepus timidus5 | KR030069 | Harbin, Heilongjiang | 17744 |
Lepus timidus6 | KR013248 | Harbin, Heilongjiang | 17759 |
Lepus tolai | KM609214 | Hefei Anhui | 17472 |
Lepus townsendii1 | NC024041 | Wyoming, USA | 17732 |
Lepus townsendii2 | KJ397609 | Wyoming, USA | 17732 |
Lepus yarkandensis1 | MG279351 | Alaer, Xinjiang | 17047 |
Ochotona curzoniae | EF535828 | Qinghai, China | 17313 |
Ochotona collaris | AF348080 | Not mentioned | 16968 |
Ochotona princeps | AJ537415 | Not mentioned | 16481 |
Lepus yarkandensis2 | MN450151 | Kuqa, Xinjiang | 17011 |
Oryctolagus cuniculus | AJ001588 | Not mentioned | 17245 |
The mitogenome of L. yarkandensis was a circular, double-stranded DNA molecule 17047 bp in size (GenBank accession number: MG279351) which is slightly longer than reported L. yarkandensis (MN450151) with 17011 bp (
Gene name | Position | Size | Location | Codon | Intergenic nucleotide bp | ||
---|---|---|---|---|---|---|---|
From | To | (bp) | H/L strand | Start | Stop | ||
tRNA-Phe | 1 | 67 | 67 | H | 0 | ||
12S rRNA | 68 | 1022 | 955 | H | 0 | ||
tRNA-Val | 1023 | 1088 | 66 | H | 0 | ||
16S rRNA | 1087 | 2668 | 1582 | H | –2 | ||
tRNA-Leu (UUR) | 2669 | 2743 | 75 | H | 0 | ||
ND1 | 2746 | 3702 | 957 | H | ATG | T | +2 |
tRNA-Ile | 3701 | 3769 | 69 | H | –2 | ||
tRNA-Gln | 3767 | 3838 | 72 | L | –3 | ||
tRNA-Met | 3848 | 3916 | 69 | H | +9 | ||
ND2 | 3917 | 4960 | 1044 | H | ATT | TAA | 0 |
tRNA-Trp | 4966 | 5032 | 67 | H | +5 | ||
tRNA-Ala | 5035 | 5101 | 67 | L | +2 | ||
tRNA-Asn | 5102 | 5174 | 73 | L | 0 | ||
tRNA-Cys | 5207 | 5273 | 67 | L | +32 | ||
tRNA-Tyr | 5274 | 5339 | 66 | L | 0 | ||
COI | 5347 | 6888 | 1542 | H | ATG | TAA | +7 |
tRNA-Ser (UCN) | 6891 | 6959 | 69 | L | +2 | ||
tRNA-Asp | 6963 | 7031 | 69 | H | +3 | ||
COII | 7032 | 7715 | 684 | H | ATG | TAG | 0 |
RNA-Lys | 7719 | 7789 | 71 | H | +3 | ||
ATP8 | 7791 | 7994 | 204 | H | ATG | TAA | +1 |
ATP6 | 7952 | 8632 | 681 | H | ATG | TAA | –43 |
COIII | 8632 | 9435 | 804 | H | ATG | T | –1 |
tRNA-Gly | 9416 | 9485 | 70 | H | –20 | ||
ND3 | 9486 | 9842 | 357 | H | ATT | TA | 0 |
tRNA-Arg | 9833 | 9899 | 67 | H | –10 | ||
ND4L | 9901 | 10197 | 297 | H | ATG | TAA | +1 |
ND4 | 10191 | 11615 | 1425 | H | ATG | T | –7 |
tRNA-His | 11569 | 11637 | 69 | H | –47 | ||
tRNA-Ser (AGY) | 11638 | 11696 | 59 | H | 0 | ||
tRNA-Leu (CUN) | 11697 | 11766 | 70 | H | 0 | ||
ND5 | 11767 | 13578 | 1812 | H | ATT | TAA | 0 |
ND6 | 13575 | 14099 | 525 | L | ATG | TAG | –4 |
tRNA-Glu | 14100 | 14167 | 68 | L | 0 | ||
Cytb | 14171 | 15310 | 1140 | H | ATG | AGG | +3 |
tRNA-Thr | 15310 | 15377 | 68 | H | –1 | ||
tRNA-Pro | 15378 | 15443 | 66 | L | 0 | ||
D-Loop | 15444 | 17047 | 1604 | H | 0 |
AT skew, GC skew, and A + T content were selected as parameters for investigating the pattern of the mitogenome nucleotide composition (
Nucleotide composition and skewness of the Lepus yarkandensis mitogenome.
A% | T% | G% | C% | Size | A+T% | ATskew | GCskew | |
---|---|---|---|---|---|---|---|---|
Total PCGs | 30.50 | 30.90 | 12.00 | 26.50 | 11417 | 61.40 | –0.007 | –0.377 |
Overall | 31.50 | 29.40 | 13.30 | 25.80 | 17047 | 60.90 | 0.034 | –0.320 |
rRNAs | 36.10 | 24.70 | 17.80 | 21.40 | 2535 | 60.80 | 0.188 | –0.092 |
tRNAs | 31.20 | 29.90 | 12.30 | 26.70 | 8295 | 61.10 | 0.021 | –0.369 |
D-Loop | 28.70 | 27.40 | 13.00 | 30.90 | 1604 | 56.10 | 0.023 | –0.408 |
CDs | 21.80 | 27.10 | 21.10 | 30.0 | 317 | 48.90 | -0.108 | –0.174 |
CSB | 30.00 | 26.2 | 11.4 | 32.4 | 920 | 56.2 | 0.068 | –0.480 |
ETAS | 31.60 | 30.80 | 9.80 | 27.80 | 367 | 62.40 | 0.013 | –0.479 |
The total length of PCGs in the L. yarkandensis mitogenome was 11,417 bp, and its base composition was 30.50% for A, 30.90% for T, 12.00% for G, and 26.50% for C with an A+T bias of 61.40%. Among the 13 PCGs, 12 were located on the heavy strand (H strand), whereas ND6 was located on the light strand (Tables
The skewness of the entire PCGs in L. yarkandensis (Table
To further estimate and understand the level of base bias between all PCGs, we calculated the AT and GC skew ratios for each PCG in the mtDNA genome of L. yarkandensis (Fig.
As with the vertebrate mtDNA genome, the majority of PCGs in the L. yarkandensis mitogenome used ATG as the start codon, although ND2, ND3, and ND5 used ATT as the start codon. Most PCGs used typical stop codons (TAA for ND2, COI, COII, ATP8, ATP6, ND4L, and ND5; TAG for ND6 and COII), whereas a small number of abnormal stop codons were observed, including AGG (Cytb), T (ND1, COIII, ND4), and TA (ND3). Moreover, nine of 13 PCGs had complete stop codons, and four genes had incomplete stop codons (Table
The Ka, Ks, and Ka/Ks values of PCGs were estimated using substitution rates (Fig.
The control region 1604 bp in length was organized between trnP and trnF genes in the L. yarkandensis mitogenome (Table
A schematic of the structural organization of the mitochondrial control region in Lepus yarkandensis. Control region flanking genes tRNA-Phe and tRNA-Pro presented in red. Conserved elements in the control region denoted by gray boxes: TAS, termination associated sequence; CD, central conserved domain; CSB, conserved sequence block. SR, short repeat; LR, long repeat.
In CSB regions, CSB1 and CSB3 were relatively conservative, and CSB2 widely varied in L. yarkandensis. This finding contradicted the results for Felis catus and Mustelidae species (
Sequences of the conserved regions in the control region of Lepus yarkandensis.
Functional domains | Nucleotide sequences |
---|---|
TAS | |
ETAS1 | ACCATTATATGTTTAATCGTACATTAAAGCTTTACCCCATGCATATAAGCTAGTACATTC |
ETAS2 | CACATACACCTACTCAACTCCACAAAACCTTATCATCAACACGGATATCCAAACCCATTACCCA |
CSB | |
CSB1 | TATCTTTTCATGCTTGACGGACATA |
CSB2 | AAACCCCCCCTACCCCC |
CSB3 | TGCCAAACCCCAAAAAC |
Except for tRNA-ser (AGY), which lacked a D stem, the other 21 tRNAs formed complete secondary structures (Suppl. material
We constructed NJ and Bayesian trees based on the complete mtDNA genome of L. yarkandensis in this study and 25 other lagomorphs published on NCBI (Fig.
We are grateful for the financial support received from the National Natural Science Foundation of China (grant numbers 31860599, 31301006) and Xinjiang Natural Science Foundation (grant number 2018D01C060).
Figure S1a, S1b
Data type: multimedia