摘要
Although a growing number of both sequence-based and microsatellite nuclear loci have been used to infer genetic structures, their relative efficiencies remain poorly understood. In our study, we used the Green-backed Tit (Parus monticolus) to explore the resolving ability of these two types of markers. The south-western and central mitochondrial DNA (mtDNA) phylogroups were divergent to some extent in sequence-based nuclear data, while mixed together in microsatellites data. The F ST values among clades were about four times lower in microsatellite loci than those in sequence-based nuclear loci. We are of the opinion that size homoplasy may have contributed to the inability of microsatellites to uncover differentiation. Our results suggest that sequence-based nuclear loci outperformed microsatellite loci in detecting population structures, especially those focused on populations with large effective population sizes. There was no significant correlation between F ST values and allelic size variability, which suggested that the efficiency of microsatellite loci in detecting genetic structure may be independent of their polymorphism. F ST is better than R ST in detecting intraspecific divergence due to the high variance of R ST . In agreement with sequence-based nuclear loci, microsatellite loci did resolve the genetic distinctness of the Taiwan Residents phylogroup. The genetic differentiation between the Taiwan Residents and continental clades may involve allopatric divergence without gene flow.
近些年来,核序列基因和微卫星标记被广泛地应用于物种遗传结构分析,然而,对于两者的有效性我们却知之甚少。本文以绿背山雀(Parus monticolus)为研究对象,探讨核序列基因和微卫星标记在解析物种遗传结构方面的有效性。绿背山雀中部和西南线粒体谱系分支在核序列基因上存在相应的遗传分化,而在微卫星数据上却不存在分化。两个谱系分支在核序列基因上的FST值是微卫星的4倍。我们认为等位基因大小异源同形(size homoplasy)可能是导致微卫星标记无法区分两个谱系分支的主要原因。我们的研究结果表明在探讨物种遗传结构,且当目标种群具有较大的有效种群数量时,核序列基因比微卫星标记具有更强的适用性。绿背山雀各线粒体谱系分支间的 FST值与等位基因数量不存在显著的相关性,该结果表明微卫星标记的有效性与等位基因的数量无关。RST值的变化范围比 FST值大,因此更不利于探讨种群间的遗传分化。与核序列基因相符,微卫星标记同样揭示了台湾支系的遗传独立性。台湾支系与大陆支系间的遗传分化可能属于严格的异域分化过程。
基金
supported by the National Science Fund for Distinguished Young Scientists (No. 30925008)
the Major International (Regional) Joint Research Project (No. 31010103901)
the CAS-IOZ Innovation Program (KSCX2-EW-J-2)
by a grant (No. O529YX5105) from the Key Laboratory of the Zoological Systematics and Evolution of the Chinese Academy of Sciences to F.M. Lei
