【作者】 于宏丽；

【导师】 刘迺发；

【作者基本信息】 兰州大学 ， 动物学， 2008， 硕士

【摘要】 石鸡(Alectoris chukar)是我国北方干旱、半干旱荒漠环境的指示性鸟类,是广布种,亚种分化众多。由于更新世冰期的影响,它们可能具有不同的进化历史和系统地理结构。本文旨在通过对mtDNA细胞色素b基因828bp序列遗传信息的分析,达到如下目的:(1)重建我国石鸡的系统地理结构,阐明更新世冷暖气候交替发生对它们系统进化的作用;(2)揭示环境因子对石鸡贺兰山亚种(A.c.potanini)遗传结构的影响(3)设计合理的取样策略(4)从遗传学角度探讨石鸡的保护问题。本文共分析了石鸡238个样本,分为形态差异明显的6个亚种:华北亚种Alectoris chukar pubescens、贺兰山亚种Alectoris chukar potanini、南疆亚种Alectoris chukar pallida、新疆亚种Alectoris chukar falki、准噶尔亚种Alectoris chukar dzungarica、疆西亚种Alectoris chukar pallescens。结果表明,石鸡的Cytb基因密码子存在偏倚,A和C比例明显高于G和T的比例。石鸡238个样本共发现28个变异位点,26种单倍型,单倍型C1为所有种群共享,所占比例为58.82%。除了准噶尔亚种、南疆亚种可能由于样本量较少,而且采样点都位于亚种分布的边缘地带而与其他大多数亚种的遗传分化较小外,其他各亚种间都有显著的遗传差异,部分的支持了传统的按表形和生境进行的亚种分类。6个亚种在系统地理结构上属于“系统发生连续,具有部分空间隔离”的地理格局。6个亚种根据单倍型系统树分为两个亚种组:A.c.pubescens-A.c.potanini亚种组和Alectoris chukar pallescens -A.c.pallida-A.c.falki-A.c.dzungarica。两亚种组间的分歧进化大约在21万年前,主要受更新世第四次冰期的影响。A.c.pallescens由于受第三次冰期的作用,与其他亚种在20.7-33.3万年前率先开始独立进化。A.c.dzungarica、A.c.pallida、A.c.falki之间的分化主要受第四次寒冷期的影响,分歧时间约10-20万年。A.c.potanini和A.c.pubescens的分歧时间为5.3万年,主要受第五次寒冷期以及暴雨泥石流的影响。可见,我国石鸡的亚种分化不是一次性完成的,而是受更新世中晚期冰期间冰期的反复作用以及更新世晚期和全新世暴雨泥石流的影响而逐步形成的。贺兰山亚种6个地理种群分为差异极显著的南北两个集群,其系统地理结构属于“系统发生连续,具有部分空间隔离”的地理格局。贺兰山亚种6个地理种群的遗传多样性与温度和降水量负相关,与日照率正相关,其中核苷酸多样性与日照率和降水量的相关性都达到了显著水平,说明日照率和降水量是影响A.c.potanini遗传多样性的决定因子。日照率和降水量对种群间遗传距离的影响较大。降水量变异系数是序列变异率的主导因子。碱基组成受海拔、日照率、降水量的影响较大。本文所选的9个环境因子中,日照率对石鸡贺兰山亚种遗传结构的影响最大。温度和降水量变异系数与贺兰山亚种遗传多样性、种群内遗传距离和序列变异率负相关,说明稳定的环境有利于遗传变异和遗传多样性的累积。石鸡采样范围可能是决定环境因子对遗传多样性影响结果不同的一个因素。本实验结果和以往的研究都表明来自采样范围较广、生境差异较大或年平均降水量相对较低的石鸡属鸟类种群的遗传多样性与温度和降水量负相关,来自采样范围较小、生境差异较小的或降水量相对较高的石鸡属种群的遗传多样性与温度和降水量正相关。对寿鹿山种群遗传多样性与样本量的研究表明,样本量为15时,单倍型多样性和核苷酸多样性都相对较高,并在15后趋于稳定,所以对石鸡遗传多样性相关研究的合理样本量大约为15。喀喇昆仑山种群(疆西亚种种群)和天山、北山、贺兰山、寿鹿山种群由于高度的地理隔离,应划为5个不同的的进化显著单元进行应重点保护。更多还原

【Abstract】 Chukar partridges(Alectoris chukar)is an indicative species of arid and semiarid environments in northern China.It.has numerous subspecies with broad distribution.These subspecies might have different evolutionary history and phylogeographical structure that were heavily affected by Pleistocene glaciations. We used polymerase chain reaction(PCR)and direct sequencing methods to infer their molecular ecology based on mitochondrial DNA(mtDNA)Cytb data.The aims are:(1)to reconstruct their phylogeographical relationships within the background of Pleistocene climate.(2)to infer the effects of environmental factors on population genetic diversity of the two partridges.(3)to design sampling strategy (4)to discuss the conservation of the two partridges as viewed from genetics.This study analyzed 238 Chukar partridges including six subspecies (A.c.pubescens,A.c.potanini,A.c.pallida,A.c.falki,A.c.drungaria, A.c.pallescens).The Codon Bias Index(CBI)showed that Cytb gene had compositional bias within chukar partridges.28 variable sites defined 26 haplotypes,all populations shared haplotype C1,which is of high frequency of 58.28%.Most of pairwise differences within 6 subpopulations were significant.Calibrated rates of molecular evolution suggested that two subspecies groups began to diverged about 0.21 million years ago,mainly affected by the Pleistocene forth frigid.During 0.15-0.24 Ma,the A.c.pallescenes began to diverged with others at and formed different subspecies 0.207-0.333,so the subspeciation of it was mainly affected by Pleistocene third frigid.The A.c.potanini and A.c.pubescens independently evolved about 0.053 Ma ago due to the effect of Pleistocene forth frigid and debries flow.The phylogeographic structure of the six subpopulations belonged to "Phylogenetic continuity,spatial separation" geographic pattern,same went the six populations of A.c.potanini,resulting from the synergistic affection of glaciers, debris flow the middle and latter of the Pleistocene.Genetic diversity of A.c.potanini decreased with increasing temperature and rainfall.However,it increased with average rate of annual sunshine.Both correlations of neucleotide diversity and average annual sunshine time as well as rainfall were significant.So,average annual sunshine time and rainfall were two main factors for genetic diversity.These two factors were also most important for genetic differrenciations within populations as well as neucleotide composition. Moreover,altitude also effected the neucleotide composition.Among nine ecology factors in this study,average annual sunshine time was the most impotant one for genetic stucture of of A.c.potanini.Genetic diversity showed negative correlation with variation coefficients of temperature and rainfall,so did genetic differrenciations and sequence differences within populations Namely,the more stable the climate,the higher the genetic diversity as well as genetic differrenciations and sequence differences within populations observed.Sampling geographic scope might effected the different results of correlation of ecology and genetic structure in Alectoris.genetic diversities of populations from spacial regions with considerable ecology differences and relatively lower rainfall tended to show negative correlation with average annual temperature and average annual rainfall.When sample size reached fifteen in SL population,both haplotype diversity and neucleotide diversity tended to keep stable,and before fifteen,genetic diversity fluctuated sharply and with no rule.So we infer the reasonable sample size for a A.chukar population would be 15.A.c.pallescens population as well as TS,BS,HL,SL populations were all highly isolated,they were met the criteria for 5 different distinct evolutionary significant units(ESU).更多还原