长江下游地区夜鹭种群微卫星变异及遗传多样性

Microsatellite variation and genetic diversity in the black-crowned night heron Nycticorax nycticorax in the lower reaches of Yangtze River

利用微卫星位点对长江下游地区夜鹭3个地方种群的遗传多样性及其种群结构进行了分析。研究结果表明:除了Ah526位点外,其他7个位点在夜鹭种群中均为高度多态。在3个地方种群中,6个微卫星位点中经Bonferroni校正后南京大校场种群和芜湖四褐山种群中分别有2个及3个位点显示杂合不足,显著偏离了哈迪-温伯平衡,这可能与夜鹭繁殖后个体的扩散能力较强及长江下游地区夜鹭存在着替代型迁徙现象有关。突变-漂移平衡分析表明,长江下游地区夜鹭种群显著具有杂合过剩的位点,这表明长江下游地区夜鹭种群已偏离了突变-漂移平衡,近期可能经历了瓶颈效应,种群数量曾经下降。地方种群间Fst分析表明,长江下游地区夜鹭地方种群间遗传分化程度较低,并没有形成显著的遗传结构,在保护与管理上可以作为同一个保护单元(或管理)

To develop an understanding of genetic diversity of the widespread waterbird, black-crowned night heron Nycticorax nycticorax three local populations in the lower reaches of the Yangtze River were investigated using microsatellite data. Eight microsatellite loci, Ah211, Ah320, Ah343, Ah421, Ah209, Ah414, Ah522 and Ah526 were selected according to the study of great blue heron Arda herodias. The allele numbers, effective allele numbers, observed heterozygosity and expected heterozygosity under Hardy-Weinberg equilibrium were estimated to characterize genetic diversity. Tests to detect excess heterzygosity in a population at mutation-drift equilibrium were analyzed. The results show that all loci were highly polymorphism except locus Ah526 in black-crowned night herons. Tests of departures from Hardy-Weinberg equilibrium indicated many loci with significant heterozygosity deficiency at P〈0.05, and these were distributed across all loci in no particular pattern. Five loci （2 in Nanjing Daxiaochang local population and 3 in Wuhu Sihesan local population） were still significant after Bonferroni correction. The populations were not in Hardy-Weinberg proportions which may be related to the wide dispersal of black-crowned night herons, especially juveniles, after nesting. Furthermore, migration of the herons could not be negligible in this case. The black-crowned night heron population in the lower reaches of the Yangtze River was significantly different from mutation-drift equilibrium with heterozygote excesses. This may indicate the population had suffered bottleneck effects in the past as well as the recent population decline. Fst analysis across all local populations and loci indicated that there were low level of divergence between the local populations, and three local populations may be protected and managed as a management unit （MU） [Acta Zoologica Sinica 51 （4） ： 657-663, 2005].