Abstract Two parapatric Rattus norvegicus subspecies, R. n. humiliatus (RNH) and R. n. caraco (RNC), are classified according to morphological divergence and are mainly distributed in North and Northeast China. Here, we aimed to explore the population genetic structure, genetic boundary, and gene flow in these rats using 16 microsatellite loci. Structure analysis and principal component analysis revealed 3 ancestral clusters. We found that the intermediate cluster exhibited higher genetic diversity and a lower inbreeding coefficient than the other 2 clusters. The genetic differentiation between the 3 clusters was significant but weak, with a higher FST value being observed between the clusters on both sides. The subspecies boundary inferred from microsatellite markers may indicate the existence of an admixture or hybridization area covering Liaoning, Inner Mongolia, and Jilin Provinces, rather than corresponding to the administrative provincial boundaries between Liaoning and Jilin. The RNH and RNC subspecies presented moderate gene exchange and an asymmetric bidirectional gene flow pattern, with higher gene flow from the RNH subspecies to the RNC subspecies, constraining speciation. Such genetic characteristics might be explained by biological processes such as dispersal ability, mate choice, and dynamic lineage boundaries.

中文翻译：

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棕色大鼠两个旁系亚种的遗传边界和基因流

摘要 两个准外生 Rattus norvegicus 亚种，R. n. 屈辱 (RNH) 和 R. n. caraco (RNC)，根据形态差异进行分类，主要分布在华北和东北地区。在这里，我们旨在使用 16 个微卫星位点探索这些大鼠的种群遗传结构、遗传边界和基因流。结构分析和主成分分析揭示了3个祖先簇。我们发现中间簇比其他两个簇表现出更高的遗传多样性和更低的近交系数。3个簇之间的遗传分化显着但较弱，在两侧的簇之间观察到更高的FST值。微卫星标记推断的亚种边界可能表明存在覆盖辽宁、内蒙古和吉林省的混合或杂交区，而不对应于辽宁和吉林之间的行政省界。RNH 和 RNC 亚种表现出适度的基因交换和不对称的双向基因流动模式，从 RNH 亚种到 RNC 亚种的基因流较高，从而限制了物种形成。这种遗传特征可以通过生物过程来解释，例如传播能力、配偶选择和动态谱系边界。RNH 和 RNC 亚种表现出适度的基因交换和不对称的双向基因流动模式，从 RNH 亚种到 RNC 亚种的基因流较高，从而限制了物种形成。这种遗传特征可以通过生物过程来解释，例如传播能力、配偶选择和动态谱系边界。RNH 和 RNC 亚种表现出适度的基因交换和不对称的双向基因流动模式，从 RNH 亚种到 RNC 亚种的基因流较高，从而限制了物种形成。这种遗传特征可以通过生物过程来解释，例如传播能力、配偶选择和动态谱系边界。