【作者】 郭华；

【导师】 吴跃峰；

【作者基本信息】 河北师范大学 ， 生态学， 2008， 硕士

【摘要】 鸻形目(Charadriiformes)鸟类是湿地的重要组成成分,具有十分重要的生态意义。关于该类群科及科以上阶元的分类地位,一直是鸟类学研究中争论的主要问题之一。长期以来,对鸻形目鸟类的研究大都是基于形态学和生态学方面。由于鸻形目鸟类很多种在形态和生活习性等方面都具有较大的相似性,依据形态学性状对其进行分类一直存在争议,这样就很有必要采用分子生物学的手段来研究这一类群之间的亲缘关系。本论文主要采用分子生物学技术和手段,通过扩增和测定鸻形目4科15种鸟类的线粒体12S rRNA基因的全序列,并结合从Genbank中下载的五种鸻形目鸟类的12S rRNA基因全序列,利用软件进行了序列变异分析,并构建了系统发生树,为阐明这一类群的系统发生关系提供了理论依据。主要研究结果如下:1. 12S rRNA基因全序列(1031bp)的特点:T、C、A、G的平均含量分别为21.4%、26.9%、31.4%和20.2%,嘌呤碱基含量51.6%略高于嘧啶碱基的含量48.3%。12S rRNA基因所有序列的平均R值为3.3,大于临界值,说明序列远未达到替换饱和。序列之间的平均遗传距离为0.115。2.整个系统树由三个大的进化枝构成:一枝为鹬类,一枝为鸥类和海雀类,另一枝为鸻类。而且鸻类位于树的基部,是最先分化出来的类群。3.在对鹬科单独进行分析时发现,阔嘴鹬(Limicola falcinellus)无论是在距离法还是简约法做的系统树中,始终位于滨鹬属内。4.由于12S rRNA基因序列的变异相当丰富,整个基因片段包含从种间到科间的进化遗传信息,构建的分子系统树所反映的鸻形目鸟类的系统发育关系与形态学上的分类有所不同,为这一类群的系统发育研究提供了分子证据,同时也说明12S rRNA基因在解决鸟类科间及种间系统关系方面具有积极的作用,可以认为12S rRNA基因是一个很好的分子标记。从中得出以下结论:1.在所研究的6个科中,鸻科是最原始的分支,是最先分歧出来的科;然后是鸥科、贼鸥科、燕鸥科和海雀科组成的鸥类一支;最后是鹬科。2.在鹬科中,滨鹬属是最晚分歧出来的一支。3.在鹬科中,阔嘴鹬与滨鹬属的几种滨鹬聚在一起,阔嘴鹬应该包含在滨鹬属之内;鹬属与滨鹬属聚成一支,说明鹬属和滨鹬属的亲缘关系比较近。4.在鸻科中,鸻属的环颈鸻和金眶鸻先聚为一支,然后再与斑鸻属的美洲金鸻聚类,说明本文所研究的鸻科的这几种鸟类的关系与形态学的分类有较高的一致性。更多还原

【Abstract】 Charadriiformes is a most important component of the Wetland ecosystem, and it has very important ecological significance. One of the main problems to controvert in avain reseach is about the classification of the family and higher level in this group. The previous researches are almost based on morphology and ecology. There is disputation about the classification based on morphological traits, because of the great similarity (convergence) in morphology, habits and other aspects among many species of Chrardriiformes. Therefore, it is necessary to study the relationships among the group using molecular biology method.Using the well-known PCR techniques, the complete mitochondrial 12S rRNA gene sequences were amplified and sequnced from fifteen spices belonging to 4 families. Sequence analysis was made using these 15 sequences combining the corresponding sequences of five species downloaded from Genbank, and phylogenetic trees weae constructed. That provides a certain evidence to illustrate the phylogenetic relationships of this group. The results show that:1. The characteristics of complete 12S rRNA gene sequences (1031bp) are as follows: average base frequencies of T, C, A and G are 21.4%,26.9%,31.4% and 20.2% respectively; The content of purine bases is 51.6%, a little higher than that of pyrimidine bases. Transtions and trsversions are the major type of nucleotide substitutions and the number of transitions is larger than that of transversions, the average ratio of transitions to transversions is 3.3. The average genetic distance in all sequences is 0.115.2. The phylogenetic tree reconstructed is composed of three clades: one is Scolopacidae, one is Laridae and Alcidae, and another is Charadriidae. Charadriidae lies on the bottom of the tree, and it is the first clade diverging from the ancestor.3. When Scolopacidae was analysed individually, Limicola falcinellus always lies in genes Calidris either in NJ trees or in MP trees, so it is doubted that Limicola falcinellus is a mumber of the genus Calidris.4. 12S rRNA gene sequence is abundant of variation; the complete sequence contains evolution information from interspecies to interfamily. Reconstructed phylogenetic tree applying this gene is different from those applying morphological traits. And it can provide molecular evidence to study the phylogeny of this group.From the result, we can conclude that:1. Among the six families researched, Charadriidae is the most primordial family, and it is the first fimily divergenced from ancestor. Laridae, Stercorariidae, Sternidae and Alcidae make up of Laridea. The last one divergenced is Scolopacidae.2. In Scolopacidae, the genus Calidris convergenced uppermost.3. In the family Scolopacidae, Limicola falcinellus always lies in genes Calidris, which implies that Limicola falcinellus shold be included in genes Calidris. Genus Tringa and Calidris gather a cluster, which implies that these two genus have close relativeness.4. In family Charadriidae, Charadrius alexandrinus and Charadrius dubius of genus Charadrius cluster first, then gather with Pluvialis fulva of genus Pluvialis. All of this shows that the molecular relationships between species of family Charadriidae in this study is in highly accord with that of morphology.更多还原