Grant's gazelles have recently been proposed to be a species complex comprising three highly divergent mtDNA lineages (Nanger granti, N. notata and N. petersii). The three lineages have nonoverlapping distributions in East Africa, but without any obvious geographical divisions, making them an interesting model for studying the early‐stage evolutionary dynamics of allopatric speciation in detail. Here, we use genomic data obtained by restriction site‐associated (RAD) sequencing of 106 gazelle individuals to shed light on the evolutionary processes underlying Grant's gazelle divergence, to characterize their genetic structure and to assess the presence of gene flow between the main lineages in the species complex. We date the species divergence to 134,000 years ago, which is recent in evolutionary terms. We find population subdivision within N. granti, which coincides with the previously suggested two subspecies, N. g. granti and N. g. robertsii. Moreover, these two lineages seem to have hybridized in Masai Mara. Perhaps more surprisingly given their extreme genetic differentiation, N. granti and N. petersii also show signs of prolonged admixture in Mkomazi, which we identified as a hybrid population most likely founded by allopatric lineages coming into secondary contact. Despite the admixed composition of this population, elevated X chromosomal differentiation suggests that selection may be shaping the outcome of hybridization in this population. Our results therefore provide detailed insights into the processes of allopatric speciation and secondary contact in a recently radiated species complex.

中文翻译：

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在瞪羚物种复合体中出现变异后继发第二基因流

格兰特（Grant）的瞪羚最近被提出是一个物种复合体，它包含三个高度不同的mtDNA谱系（Nanger Granti，N。notata和N. petersii）。）。这三个谱系在东非具有不重叠的分布，但没有明显的地理划分，这使它们成为详细研究异源物种形成的早期演化动力学的有趣模型。在这里，我们使用通过106个瞪羚个体的限制性位点相关（RAD）测序获得的基因组数据，阐明了Grant瞪羚发散的基础进化过程，表征了他们的遗传结构，并评估了主要谱系之间的基因流的存在。物种复合体。我们将物种差异追溯到134,000年前，这在进化方面是最近的。我们在N. Granti中发现了种群细分，这与先前建议的N. g。两个亚种相吻合。格兰蒂和N. g。罗伯茨二世。而且，这两个血统似乎在马赛马拉（Marai Mara）杂交。考虑到它们的极端遗传分化，也许更令人惊讶的是，N。Granti和N. petersii在Mkomazi中也显示出长期混合的迹象，我们将其鉴定为杂种，极有可能是由异源谱系进行二次接触而建立的。尽管该种群的组成混合，但X染色体分化的升高提示选择可能会影响该种群杂交的结果。因此，我们的结果提供了对最近辐射的物种复合物中异源物种形成和次级接触过程的详细见解。