黑嘴鸥种群的遗传分化与迁徙模式

Population genetic divergence and migration pattern of the Saunders's gull Larus saundersi

用分子生物学方法研究了黑嘴鸥(Larus saundersi)种群的遗传结构和分化。对我国黑嘴鸥现存的3个地方种群50个样本的线粒体DNA控制区部分片段进行了序列测定,结合已公布的的两个韩国样本的序列,比对后所获得的550bp的序列中,共发现49个变异位点,定义了37种线粒体单元型,其中仅1种为我国3个地方种群间共享单元型,多数为各地方种群内特有。我国3个地方种群内的单元型多样性和核苷酸多态性都很高;4个地方种群合并成一个大种群时,其线粒体单元型多样性与核苷酸多样性仍很高,分别为0.974%±0.012%和0.510%±0.042%。进一步分析表明,4个地方种群间核苷酸歧异度在0.433%-0.585%之间,种群分化程度FST在-0.03176-0.48063之间,基因流Nm在1.03-33.79之间,平均遗传距离为0.0051±0.0011。UPGMA系统发生树及最大简约网络图表明,黑嘴鸥的演化关系呈现星状辐射,单元型之间呈现一种混杂的分布格局,地方种群没有形成明显的系统地理结构。同时运用彩色旗标技术,初步掌握了4个地方种群迁徙规律。对比分子研究结果,验证了不同地方种群间的遗传分化与其迁徙模式基本一致,同时认为黑嘴鸥不同地方繁殖种群从越冬地返回繁殖地的过程中会发生交叉。最后,鉴于黑嘴鸥不同地方种群间的遗传分化不显著,其迁徙行为具有差异性,建议在保护和遗传管理中应分别对待。

A molecular method was used to reveal population genetic structure and differentiation of Saunders＇ s Gull Larus saundersi. The mitochondrial control region （CR） sequence variation was assayed from 50 samples, that were collected from 3 current breeding sites in China ： Yancheng of Jiangsu, Yellow River Delta of Shandong and Shuangtaihekou of Liaoning.. With the addition of sequences of 2 South Korean samples obtained from the published literature, a total of 49 variable sites were detected and 37 haplotypes were defined from the aligned 550 bp of the 5＇ CR. Only 1 haplotype was shared by all 3 sub-populations in China and most of the haplotypes were unique to a sub-population. There were very high diversities in hyplotypes and nucleotides within each population. Over all diversities for all four sub-populations were still quite high （ h = 0.974% ± 0.012% , n =- 0.510% ± 0.042%）. The range of the nucleotide divergence, the populations was between 0.457% - 0.585% - 0.03176 - 0.48063, pairwise FST, and the gene flow （Nm ） between the 4 and 1.03- 33.79 respectively. The mean genetic distance among the 4 populations was 0.0051 ± 0.0011. UPGMA tree and statistical parsimony cladogram showed a very shallow phylogenetic tree and a star-like haplotype network, which indicated that no distinctive geographic phylogeography has occurred among the 4 sub-populations. At the same time, the color flagging technique was used to reveal the migration patterns of the 4 breeding sub-populations. The results of the migration and genetic studies are very similar. High genetic diversities in the four subpopulations might result from gene exchange when the gulls return from their wintering areas. Finally, considering the migratory behavior and low genetic differences between subopulations, we suggest taking different management measures for species and genetic conservation of Saunders＇s gull