Ackermann Rebecca R, Schroeder Lauren, Rogers Jeffrey, Cheverud James M
Department of Archaeology, University of Cape Town, Rondebosch 7701, South Africa.
Department of Archaeology, University of Cape Town, Rondebosch 7701, South Africa.
J Hum Evol. 2014 Nov;76:54-62. doi: 10.1016/j.jhevol.2014.05.004. Epub 2014 Jun 13.
Hybridization may have played a substantial role in shaping the diversity of our evolving lineage. Although recent genomic evidence has shown that hybridization occurred between anatomically modern humans (AMHS) and Neanderthals, it remains difficult to pin down precisely where and when this gene flow took place. Investigations of the hybrid phenotype in primates and other mammals are providing models for identifying signatures of hybridization in the fossil record. However, our understanding of intra- and inter-taxon variation in hybrids is still limited. Moreover, there is little evidence from these studies that is pertinent to the question of how long hybrid skeletal traits persist in descendants, and therefore it is not clear whether observed hybrid phenotypes are evidence of recent (e.g., F1) or much earlier hybridization events. Here, we present an analysis updating a previous study of cranial variation in pedigreed olive and yellow baboons and their hybrids. Results suggest that traits previously associated with hybrids in baboons and other mammalian species are also present in this expanded data set; many of these traits are highly heritable, confirming a genetic basis for their variation in this mixed population. While F1 animals - and especially F1 males - still have the highest number of dental anomalies, these and other atypical traits persist into later hybrid generations (such as F2 and B1). Moreover, non-F1 recombinants also show extremely rare trait variations, including reduced canines and rotated teeth. However, these results must be considered in light of the possibility that some founding individuals may have themselves been unrecognized hybrids. Despite this, the data are compelling, and indicate once again that further controlled research remains to be done on primates and other mammals in order to better understand variation in the hybrid phenotype.
杂交可能在塑造我们进化谱系的多样性方面发挥了重要作用。尽管最近的基因组证据表明解剖学上的现代人类（AMHS）与尼安德特人之间发生了杂交，但仍难以精确确定这种基因流动发生的地点和时间。对灵长类动物和其他哺乳动物杂交表型的研究正在为识别化石记录中的杂交特征提供模型。然而，我们对杂交种内和种间变异的理解仍然有限。此外，这些研究几乎没有提供与杂交骨骼特征在后代中持续多长时间这一问题相关的证据，因此尚不清楚观察到的杂交表型是近期（例如F1）还是更早杂交事件的证据。在这里，我们提供了一项分析，更新了之前对纯种橄榄狒狒和黄狒狒及其杂交种颅骨变异的研究。结果表明，之前在狒狒和其他哺乳动物物种中与杂交种相关的特征在这个扩展的数据集中也存在；其中许多特征具有高度遗传性，证实了它们在这个混合种群中变异的遗传基础。虽然F1代动物——尤其是F1代雄性——仍然有最多的牙齿异常，但这些和其他非典型特征在后来的杂交代（如F2和B1）中仍然存在。此外，非F1重组体也表现出极其罕见的特征变异，包括犬齿缩小和牙齿旋转。然而，考虑到一些奠基个体本身可能是未被识别的杂交种这一可能性，必须对这些结果加以考量。尽管如此，这些数据很有说服力，并再次表明，为了更好地理解杂交表型的变异，仍需对灵长类动物和其他哺乳动物进行进一步的对照研究。
