Data from: The breakdown of genomic ancestry bocks in hybrid lineages given a finite number of recombination sites

When a lineage originates from hybridization genomic blocks of contiguous ancestry from different ancestors are fragmented through genetic recombination. The resulting blocks are delineated by so called “junctions”, which accumulate with every generation that passes. Modeling the accumulation of ancestry block junctions can elucidate processes and timeframes of genomic admixture. Previous models have not addressed ancestry block dynamics for chromosomes that consist of a finite number of recombination sites. However, genomic data typically consist of informative markers that are interspersed with fragments for which no ancestry information is available. Hence, repeated recombination events may occur between markers, effectively removing existing junctions. Here, we present an analytical treatment of the dynamics of the mean number of junctions over time, taking into account the number of recombination sites per chromosome, population size, genetic map length and the frequency of the ancestral species in the founding hybrid swarm. We describe the expected number of junctions using equidistant molecular markers and estimate the number of junctions using random markers. This extended theory of junctions thus reflects properties of empirical data and can serve to study the genomic patterns following admixture.当一个谱系源自杂交事件时，携带不同祖先连续遗传背景的基因组区块会通过遗传重组发生碎片化。由此产生的区块由所谓的"接合点（junctions）"所界定，且每经过一代，接合点的数量便会累积增加。对祖先区块接合点的积累过程进行建模，可阐明基因组遗传混合的具体过程与时间尺度。以往的模型尚未针对由有限重组位点构成的染色体，开展祖先区块动态变化的相关研究。然而，基因组数据通常包含具有遗传信息的分子标记，这些标记之间夹杂着无法获取祖先背景信息的基因组片段。因此，标记位点之间可能反复发生重组事件，进而有效清除已存在的接合点。本研究针对随时间变化的平均接合点数量动态过程开展解析性分析，同时纳入了每条染色体的重组位点数、种群大小、遗传图谱长度以及奠基杂交群体中祖先物种的频率等关键参数。我们推导了基于等距分子标记的预期接合点数量，并提出了基于随机标记的接合点数量估算方法。因此，这套拓展后的接合点理论能够反映经验基因组数据的真实特征，可用于探究遗传混合后的基因组模式。