白鹭脱落羽毛的微卫星个体识别研究

Microsatellite Individual Identification for Moulted Feathers in Egretta garzetta

利用鹭科鸟类已有微卫星引物进行跨种扩增筛选，获得12对可用于白鹭（Egretta garzetta）的微卫星引物，结合非损伤采集的脱落羽毛样品，在物种分子鉴定和性别分子鉴定的基础上，建立适用于羽毛样品个体识别分析的微卫星基因分型技术体系．在中国沿海的3个白鹭繁殖种群的181样品中，19个羽毛样品由于DNA质量较差未能有效鉴定物种．119个羽毛样品成功地鉴定为白鹭个体，物种鉴定结果可重复率达93．8％．性别鉴定结果可重复率94．1％，119个白鹭羽毛样品当中的28．57％为雄性．基因分型得到各个位点的等位基因数7～22个，观察杂合度和期望杂合度分别为0．623-0．875和0．779～0．918，没有位点偏离哈迪一温伯格平衡，基因分型错误率为1．2％．个体识别分析发现其中的2个样品为相同基因型，为重复采集自同一个体脱落的不同羽毛．本研究结果将为深入研究白鹭种群遗传结构、扩散模式等保护遗传学问题奠定了基础，并且能够为其他鹭科鸟类的脱落羽毛的物种鉴定、性别鉴定、个体识别提供参考．

Little egret（Egretta garzetta）is a worldwidely distributed waterbird which inhabits fresh or saline wetlands and recently is threatened by wetland degradation and loss. As egrets and herons mostly nest on canopy trees, and nestlings are often difficult to access for sampling,noninvasive collection of naturally molted feathers of these ardeid birds can provide an important source of DNA in conservation genetic analyses. However, the E. garzetta in a heronry were often mixed with cattle egret （Bubulcus ibis）, Chinese pond-heron （Ardeola bacchus）,great egret （Ardea alba） and Chinese egret （Egretta eulophotes）, and the molted feathers of E. garzetta were difficult to distinguish from those of other colonial ardeid species due to their same white color,similar feather size and morphological appearance. Moreover, sex identification and individual identification of adult E. garzetta is difficult because adults are sexually monomorphic and similar in their exterior characteristics. Therefore, reliable species identification, sex identification and indi- vidual identification method of the molted feathers of E. garzetta through the molecular markers has become more urgent and valua- ble. Here, 12 microsatellite loci with high polymorphism were obtained for little egret by cross-species amplification, and microsatellite genotyping technique for individual identification of little egret molted feathers were established after the species identification and sex identification of these molted feathers. Among 181 molted feather samples from three breeding populations of E. garzetta along the coastline of China, 19 feather samples could not be identified for species because of their low DNA quality. 119 feather samples were successfully identified as the species of little egret and the repeat proportion of species identification was 93.8%. The repeat propor- tion of sex identification was 94.1 ~ and 28.57~ of 119 feather samples were identified as male. Basing on the genotyping,the num- ber of alleles ranges from 7 to 22 per locus,and the observed and expected heterozygosity ranged from 0. 623 to 0. 875 and 0. 779 to 0. 918, respectively. No locus deviated significantly from Hardy-Weiberg equilibrium. The error rate of genotyping was 1.2 ~. In indi- vidual identification of molted feather,2 samples shared the same genotypes,indieating that these two feathers were repeatly collected from one individual. These results will provide a groundwork for further studies on the conservation genetics such as genetic structure and dispersal pattern of population in little egret, and give a reference for species identification, sex identification and individual identi- fication of molted feathers in other ardeids.