【作者】 李佳琦；

【导师】 刘迺发；

【作者基本信息】 兰州大学 ， 动物学， 2008， 硕士

【摘要】 子午沙鼠(Meriones meridianus)属啮齿目(Rodentia),仓鼠科(Cricetidae),沙鼠亚科(Gerbillinae),沙鼠属(Meriones),是欧亚大陆中部荒漠、半荒漠的鼠种。本文利用PCR-直接测序的方法,以mtDNA控制区基因为遗传标记,研究子午沙鼠的分子进化。共测定和分析了8个种群(格尔木、榆中、武威、金塔、苏干湖、东大山、民勤、沙坡头)88个样本,得到512bpDNA序列,共发现75个变异位点,56个单倍型。子午沙鼠8个种群间碱基含量差异显著,且T—C间的转换次数(52次)明显比A—G间(17次)的高的多。这些说明子午沙鼠种群mtDNA控制区基因的变异主要是由嘧啶的变异引起的。8个种群间无共享单倍型。斑块生境对基因交流有阻隔作用,榆中种群与其他7个种群间没有基因交流。格尔木种群与其他种群间存在遗传分化(P＜0.01),但是又与东大山种群,民勤种群和沙坡头种群有比较高的基因流(分别为1.104,1.125,1.699)。提示着格尔木种群与东大山、民勤和沙坡头这三个种群之间历史上曾发生过隔离事件。种群间基因流与种群的地理距离存在着显著的负相关关系,分化指数与地理距离之间存在着正相关关系,提示地理距离对种群间的交流存在影响。核苷酸多样性与温度呈显著的正相关关系。根据分子钟分析,格尔木种群和榆中种群是大约在20万年前与其他种群产生分歧的。岐点分布法分析提示子午沙鼠的种群可能在1.53万年前经历了种群扩张事件,验证了间冰期对物种扩张的重要作用。更多还原

【Abstract】 Mid-day gerbil(Meriones meridianus)is a species of rat,which lived in desert,semi-desert of Central Eurasian continent.It distributes in northern China Mongolia,Kazakhstan,rajikistan,Afghanistan,Iran and other East Asian and Central Asian countries and regions.We used polymerase chain reaction(PCR)and direct sequencing methods to infer their molecular evolution based on mitochondrial DNA(mtDNA) control-region data.This study seqenced and analyzed 88 Mid-day gerbils inluding 8 populations,gained 512bp DNA sequence.A total of 75 variable sites defined 56 haplotypes in 88 88 Mid-day gerbils.There were significant differences in nucleotide composition among the population level.Transitions between T and C(54)are much more than transitions between A and G(17),which showed that the differences of nucleotide composition in the Mid-day gerbil were caused by pyridine.Patch habitat could be a barrier to gene exchange,there is no gene flow between Yuzhong population and other populations.Geermu population and other populations have genetic differentiation(P＜0.01),but have gene flow with Dongdashan,Minqin and Shapotou population,respectively.This indicate that Geermu population and this 3 populations had occurred isolated incidents.There was significant negative relationship between geographical distance and the gene flow,and significant positive relationship between geographical distance and the genetic differetial index(Fst).This indicate that geographical distance have influence on intercommunion between populations.There was significant negative relationship between the nucleotide diversity and temperature.According to molecular clock,Yuzhong population and Geermu population divaricated to other populations at 200 thousand years ago.Mismatch distribution analysis indicate Mid-day gerbil population had experienced a population expansion at 15.3 thousand years ago,which validated interglacial have important effect on species expansion.更多还原