Calibration of partial anatidae molecular clocks | 鸭科部分类群分子钟的标定

صينى. 目的估计鸭科鸟类间的分歧时间，了解鸭科不同鸟类的遗传背景。方法测定鸿雁家鹅15个品种、灰雁家鹅2个品种共44个个体的细胞色素b基因的全序列。将获得的鸿雁家鹅和灰雁家鹅的一致序列（2条）与GenBank中已知的鸟类细胞色素b基因部分序列（共13条；其中，鸡形目4条、鸭科鸟类9条）一起组成共15条序列作为本研究的数据集，并以鸡形目与雁形目（鸡/绿头鸭）的分歧时间（89.8 MYA）为锚定点，对鸭科的分子钟进行顺序标定。结果雉科（Gallus gallus和Coturnix japonica1、Coturnix japonica4、Coturnix chinensis）与鸭科（Anas platyrhynchos、Anas poecilorhyncha；Bucephala clangula；Chloephaga picta；Cairina moschata；Somateria mollissima和 Anser anser、Anser cygnoides、Anser albifrons，共6个属）间的分歧时间的估计值为101.798 MYA（泊松模型）和129.461 MYA（Г模型）；雁属（Anser anser、Anser cygnoides和Anser albifrons）与5个鸭属（Anas platyrhynchos、Anas poecilorhyncha；Bucephala clangula；Chloephaga picta；Cairina moschata和Somateria mollissima）间的分歧时间为55.1225 MYA（泊松模型）和62.5223 MYA（Г模型）。结论雉科与鸭科、雁属与鸭属两个接近基部类群的分歧时间发生在白垩纪（146―65 MYA），支持鸟类早期历史发生在白垩纪的观点。

إنجليزي. ObjectiveThe divergence times of Anatidae were estimated in order to investigate their genetic background. Method The mitochondrial cytochrome b (Cyt b) gene sequences of 44 individuals in Chinese domestic geese (15 breeds) and European domestic geese (2 breeds) were sequenced. The consensus sequence of Cyt b was obtained from the Anser anser and Anser cygnoides, respectively, together with 13 partial sequences of Cyt b gene in other birds (4 sequences form Galliformes, 9 from Anseriformes ) provided at NCBI, were totally constructed a 15 sequences database for the next step analysis. And the divergence time between Anseriformes and Galliformes was chosen as an anchor point to calibrate the Anatidae molecular clocks using a sequence calibration method. ResultThe results show that the estimation of the divergence time between Phasianidae and Anatidae is 101.798 MYA (Poisson Model) and 129.461 MYA (Gamma Model). The estimation of divergence time between Anser and Anatinae is 55.1225 MYA (Poisson Model) and 62.5223 MYA (Gamma Model). ConclusionThe divergence of the two basal groups（Phasianidae/Anatidae, Anser/Anatinae）took place in the Cretaceous period(146-65 MYA). These results are consistent with the view that avian was originated in the Cretaceous period.