Department of Archaeology, University of Cape Town, South Africa; Human Evolution Research Institute, University of Cape Town, South Africa.
Department of Archaeology, University of Cape Town, South Africa; Human Evolution Research Institute, University of Cape Town, South Africa; Department of Neuroscience, Washington University School of Medicine, USA; School of Human Evolution and Social Change, Arizona State University, USA.
J Hum Evol. 2018 Mar;116:57-74. doi: 10.1016/j.jhevol.2017.12.002. Epub 2018 Feb 8.
Hybridization occurs in a number of mammalian lineages, including among primate taxa. Analyses of ancient genomes have shown that hybridization between our lineage and other archaic hominins in Eurasia occurred numerous times in the past. However, we still have limited empirical data on what a hybrid skeleton looks like, or how to spot patterns of hybridization among fossils for which there are no genetic data. Here we use experimental mouse models to supplement previous studies of primates. We characterize size and shape variation in the cranium and mandible of three wild-derived inbred mouse strains and their first generation (F) hybrids. The three parent taxa in our analysis represent lineages that diverged over approximately the same period as the human/Neanderthal/Denisovan lineages and their hybrids are variably successful in the wild. Comparisons of body size, as quantified by long bone measurements, are also presented to determine whether the identified phenotypic effects of hybridization are localized to the cranium or represent overall body size changes. The results indicate that hybrid cranial and mandibular sizes, as well as limb length, exceed that of the parent taxa in all cases. All three F hybrid crosses display similar patterns of size and form variation. These results are generally consistent with earlier studies on primates and other mammals, suggesting that the effects of hybridization may be similar across very different scenarios of hybridization, including different levels of hybrid fitness. This paper serves to supplement previous studies aimed at identifying F hybrids in the fossil record and to introduce further research that will explore hybrid morphologies using mice as a proxy for better understanding hybridization in the hominin fossil record.
杂交发生在许多哺乳动物谱系中，包括灵长类动物。对古代基因组的分析表明，我们的谱系与欧亚大陆其他古老人类之间的杂交在过去发生了多次。然而，我们仍然有限的经验数据来了解杂种骨骼的外观，或者如何发现没有遗传数据的化石中杂交的模式。在这里，我们使用实验小鼠模型来补充以前对灵长类动物的研究。我们描述了三个野生近交系小鼠及其第一代（F）杂种的颅骨和下颌骨的大小和形状变化。我们分析中的三个亲代分类群代表了与人类/尼安德特人/丹尼索万人及其杂种在野外成功繁殖的时间大致相同的谱系。还比较了身体大小，通过长骨测量来量化，以确定杂交的识别表型效应是否局限于颅骨或代表整体身体大小的变化。结果表明，在所有情况下，杂种颅骨和下颌骨的大小以及四肢长度都超过了亲代分类群。所有三种 F 杂种杂交都显示出相似的大小和形态变化模式。这些结果与早期对灵长类动物和其他哺乳动物的研究基本一致，表明杂交的影响在非常不同的杂交情况下可能相似，包括杂种适应性的不同水平。本文旨在补充以前旨在识别化石记录中 F 杂种的研究，并引入进一步的研究，使用小鼠作为代理来探索杂交形态，以更好地理解人类化石记录中的杂交。
