Department of Population Genetics, National Institute of Genetics, Mishima, Japan.
PLoS One. 2011;6(9):e25549. doi: 10.1371/journal.pone.0025549. Epub 2011 Sep 29.
Inferences of ancient sex-biased migration patterns using sex-linked genetic markers are usually difficult because of a stochastic process of allele fixation. Nevertheless, incongruent phylogenetic trees between different sex-linked markers and between sex-linked and autosomal markers are frequently interpreted as a signature of sex-biased migration without further statistical evaluation. I investigated the types of incongruent phylogenetic trees from which past sex-biased migration events can be statistically supported under the coalescent model. In the case of mammals, detecting a sex-biased migration pattern is not guaranteed by comparing the phylogenetic pattern of mitochondrial and Y-chromosomal loci. Likewise, evidence of introgression at a mitochondrial locus, but not at autosomal loci, does not support the hypothesis of an ancient female-biased migration pattern with statistical significance. In contrast, evidence of introgression at ≥ 5 unlinked autosomal loci, but not at a Y-chromosomal locus, would reject the null hypothesis of a sexually equal migration rate with statistical significance. A similar argument can be made to infer a male-biased migration pattern. Furthermore, the investigation of many recombining sex-biased markers such as X-chromosomal loci in mammals has the potential to efficiently detect ancient sex-biased demographic patterns.
利用性连锁遗传标记推断古代性别偏向的迁移模式通常是困难的，因为等位基因固定是一个随机过程。然而，不同性连锁标记之间以及性连锁和常染色体标记之间的不匹配系统发育树经常被解释为性别偏向迁移的特征，而没有进一步的统计评估。我研究了在合并模型下，从哪些类型的不匹配系统发育树可以从统计学上支持过去的性别偏向迁移事件。就哺乳动物而言，通过比较线粒体和 Y 染色体基因座的系统发育模式并不能保证检测到性别偏向的迁移模式。同样，线粒体基因座上有基因渗入的证据，但常染色体基因座上没有，这并不能以统计学意义支持古代雌性偏向的迁移模式的假设。相比之下，如果在 5 个以上不相关的常染色体基因座上有基因渗入的证据，但在 Y 染色体基因座上没有，那么就可以以统计学意义拒绝性别迁移率相等的零假设。可以用类似的论点来推断雄性偏向的迁移模式。此外，对哺乳动物中许多重组的性别偏向标记（如 X 染色体基因座）进行调查，有可能有效地检测到古代性别偏向的人口模式。
