基于线粒体DNA控制区的石鸡华北亚种的种群历史动态研究

隶属于鸟纲鸡形目雉科的石鸡是一个多型种,在我国已有7个亚种被报道,其中石鸡华北亚种是我国的特有鸟。用石鸡华北亚种(Alectoris chukar pubescens)12个地理种群112个样本的线粒体DNA控制区(mt DNA CR)1154 bp序列的信息研究了石鸡华北亚种的种群历史动态。112个样本中共发现28个变异位点,定义了29种单倍型,其中12个地理种群的50个样本共享单倍型H1,8个地理种群的16个样本共享单倍型H4。地理种群间存在较大的基因流,且种群间没有由于地理距离产生隔离的证据。负的Tajima(D=-1.336,P0.05)和Fu(Fs=-1.720,P0.05)统计检验值及错配分布的单峰模式都支持石鸡华北亚种经历了种群扩张。石鸡华北亚种大部分种群的错配分布与种群过去的扩张相一致,扩张发生在晚更新世中期的第五寒冷期(0.027—0.06 Ma)。推测其扩张的原因可能为:1)更新世期间我国北方地区没有发生大规模的冰川,2)青藏高原的隆升使我国北方干旱化和荒漠化加剧利于石鸡种群的扩散。武都(WD)位于东洋界,而石鸡是典型的古北界的鸟种,表明WD种群可能是石鸡在东洋界的一个建群种,因此需要给予充分的关注。

Demographic history of Alectoris chukar pubescens based on mitochondrial DNA control region

The chukar partridge (Alectoris chukar, Aves, Galliformes) is a polytypic species, with 17 described subspecies globally. Chukar partridge has a very wide distribution, ranging from east Balkans and the adjacent Mediterranean islands to central Asia and up into northeastern China. There are seven described subspecies in China: A. c. pubescens, A. c. potanini, A. c. ordoscensis, A. c. pallida, A. c. falki, A. c. dzungarica and A. c. pallescens. Of the seven subspecies, A. c. pubescens and A. c. pallida are endemic to China. The region which chukar partridges inhabit includes two distinct climatic types, the arid and semi-arid climate region in the west and temperate monsoon region in the east in China. Chukar partridge is a very important hunting bird in northern China. Currently, populations of chukar partridges in this desert area are threatened by hunting pressure and human persecution on the desert area of northern China. Previous studies have focused on the following aspects, such as phylogeography, introgression and genetic structure. These studies sought to address the scarcity of demographic information on chukars, in particular the subspecies endemic to China, A. c. pubescens and A. c. pallida. The present study employed a direct sequencing method to investigate the past demographic changes in 112 A. c. pubescens specimens sampled from 12 populations. A total of 1154-bp sequences of mitochondrial DNA control region data were sequenced, and 28 polymorphic sites defined 29 haplotypes. The most common haplotype, H1, was shared by 50 samples from 12 populations and the second most common haplotype, H4, was shared by 16 samples which came from eight populations. The gene flow estimate revealed that high gene flow occurs among the 12 populations. No evidence of isolation by geographic distance among the populations was observed. The combination of low nucleotide and high haplotype diversity, and the shape of the mismatch distributions both suggest that A. c. pubescens has undergone a recent population expansion. The recent expansion hypothesis is also supported by the common haplotypes (H1 and H4) shared between geographically distinct regions and by the non-significant mismatch distribution analysis indicating a demographic population expansion. Neutrality tests also suggested that A. c. pubescens has undergone a population expansion. The combination of a negative Tajima''s D (D=-1.336, P < 0.05), Fu''s Fs (Fs=-1.720, P < 0.05), and a unimodal of mismatch distributions of A. c. pubescens are consistent with past population expansion. Our results revealed that most A. c. pubescens populations experienced population expansion during 0.027-0.06 Ma. Based on the expansion time, we speculate that the expansion of the chukar, occurring in the metaphase of the late Pleistocene (the fifth cold period), may have resulted from two reasons: 1) there were no large-scale glacier effect in north China during Pleistocene, 2) the uplift of the Qinghai-Tibet Plateau resulted in the aggravation of the drought and desertification, both of which are suitable for population expansion of chukar partridge. The chukar partridge inhabits Palearctic regions; however, the WD population, located in the Oriental realm, may have been a founder population in this region. Therefore, this particular population should be treated as a stand-alone management unit and further investigations into its ecology should be carried out.