Barton N H, Wilson I
Institute of Cell, Animal and Population Biology, University of Edinburgh, U.K.
Philos Trans R Soc Lond B Biol Sci. 1995 Jul 29;349(1327):49-59. doi: 10.1098/rstb.1995.0090.
Any sample of genes traces back to a single common ancestor. Each gene also has other properties: its sequence, its geographic location and the phenotype and fitness of the organism that carries it. With sexual reproduction, different genes have different genealogies, which gives us much more information, but also greatly complicates population genetic analysis. We review the close relation between the distribution of genealogies and the classic theory of identity by descent in spatially structured populations, and develop a simple diffusion approximation to the distribution of coalescence times in a homogeneous two-dimensional habitat. This shows that when neighbourhood size is large (as in most populations) only a small fraction of pairs of genes are closely related, and only this fraction gives information about current rates of gene flow. The increase of spatial dispersion with lineage age is thus a poor estimator of gene flow. The bulk of the genealogy depends on the long-term history of the population; we discuss ways of inferring this history from the concordance between genealogies across loci.
任何基因样本都可追溯到一个共同的祖先。每个基因还有其他特性：其序列、地理位置以及携带它的生物体的表型和适应性。通过有性繁殖，不同的基因有不同的谱系，这为我们提供了更多信息，但也极大地复杂化了群体遗传学分析。我们回顾了谱系分布与空间结构群体中经典的近亲繁殖理论之间的密切关系，并针对均匀二维栖息地中合并时间的分布开发了一种简单的扩散近似方法。这表明，当邻域大小较大时（如大多数群体那样），只有一小部分基因对关系密切，只有这一小部分能提供有关当前基因流动速率的信息。因此，随着谱系年龄增长空间分散度的增加是基因流动的一个较差估计指标。大部分谱系取决于群体的长期历史；我们讨论了从不同基因座间谱系的一致性推断这一历史的方法。
