Fu Yong, Li Wei, Duo Hong, Guo Zhi-Hong, Li Ying, Zhang Yan-Ming
College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi, 712100, China.
Academy of Animal and Veterinary Medicine, Qinghai University, Xining, Qinghai, 810016, China.
Parasit Vectors. 2016 Mar 12;9:145. doi: 10.1186/s13071-016-1416-6.
Hypoderma bovis and H. sinense (Diptera: Oestridae) mainly parasitise cattle and yaks. The two parasites are pathogenic and cause economic losses that result from reduced amounts of livestock products, including milk, meat, and skin. Genetic diversity and population genetic structure of H. bovis and H. sinense have not been evaluated, but could be used to inform appropriate strategies to control these parasites.
We cloned and sequenced part of the mitochondrial cytochrome c oxidase subunit I (COI) gene from 60 H. bovis isolates and 52 H. sinense isolates from five locations in Qinghai Province, China, to identify polymorphisms, and infer their phylogenetic relationships, historical population expansions, and divergence time.
We identified 17 COI haplotypes from the H. bovis samples, and 23 COI haplotypes from the H. sinense samples. The haplotype and nucleotide diversities were 0.738 and 0.00202 for H. bovis, and 0.867 and 0.00300 for H. sinense, respectively, which indicates rich genetic diversity in H. bovis and H. sinense populations. Bayesian phylogenetic analysis revealed that the two species are monophyletic, and geographical structuring of haplotypes was significantly different in H. sinense (P < 0.05), but not H. bovis. Neutrality tests and mismatch distribution statistical analysis revealed that populations of the two species have undergone demographic expansions. The divergence three Hypoderma spp. (H. bovis, H. lineatum, and H. sinense) was estimated to have occurred approximately 4.5 million years ago (Mya), which indicates that the rapid uplift of the Qinghai-Tibetan Plateau during the late Miocene-Pliocene was associated with divergence of Hypoderma species.
Results of the present study revealed that both H. bovis and H. sinense displayed high genetic diversity and widespread population genetic differentiation within and among populations; these data, along with the molecular phylogeny, demographic history, and divergence time estimation, provide new insight into evolutionary history of these species. These findings will help elucidate speciation in Hypoderma and provide theoretical basis for epidemiological surveillance and control of these species on the Qinghai-Tibetan Plateau.
牛皮蝇和中华皮蝇（双翅目：狂蝇科）主要寄生于牛和牦牛。这两种寄生虫具有致病性，会导致包括牛奶、肉类和皮革在内的畜产品产量下降，从而造成经济损失。目前尚未评估牛皮蝇和中华皮蝇的遗传多样性及种群遗传结构，但这些信息可用于制定合适的寄生虫控制策略。
我们从中国青海省五个地点的60份牛皮蝇分离株和52份中华皮蝇分离株中克隆并测序了线粒体细胞色素c氧化酶亚基I（COI）基因的部分序列，以鉴定多态性，并推断它们的系统发育关系、历史种群扩张及分化时间。
我们在牛皮蝇样本中鉴定出17种COI单倍型，在中华皮蝇样本中鉴定出23种COI单倍型。牛皮蝇的单倍型多样性和核苷酸多样性分别为0.738和0.00202，中华皮蝇分别为0.867和0.00300，这表明牛皮蝇和中华皮蝇种群具有丰富的遗传多样性。贝叶斯系统发育分析表明，这两个物种均为单系群，中华皮蝇的单倍型地理结构存在显著差异（P < 0.05），而牛皮蝇则没有。中性检验和失配分布统计分析表明，这两个物种的种群都经历了种群扩张。估计三种皮蝇属物种（牛皮蝇、纹皮蝇和中华皮蝇）的分化发生在约450万年前，这表明中新世晚期至上新世期间青藏高原的快速隆升与皮蝇属物种的分化有关。
本研究结果表明，牛皮蝇和中华皮蝇在种群内和种群间均表现出高遗传多样性和广泛的种群遗传分化；这些数据以及分子系统发育、种群历史和分化时间估计，为这些物种的进化历史提供了新的见解。这些发现将有助于阐明皮蝇属的物种形成，并为青藏高原这些物种的流行病学监测和控制提供理论依据。
