Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, P.O. Box 1066, N-0316 Oslo, Norway.
Department of Biology, Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
Sci Adv. 2017 Jun 14;3(6):e1602996. doi: 10.1126/sciadv.1602996. eCollection 2017 Jun.
Hybridization is widespread in nature and, in some instances, can result in the formation of a new hybrid species. We investigate the genetic foundation of this poorly understood process through whole-genome analysis of the hybrid Italian sparrow and its progenitors. We find overall balanced yet heterogeneous levels of contribution from each parent species throughout the hybrid genome and identify areas of novel divergence in the hybrid species exhibiting signals consistent with balancing selection. High-divergence areas are disproportionately located on the Z chromosome and overrepresented in gene networks relating to key traits separating the focal species, which are likely involved in reproductive barriers and/or species-specific adaptations. Of special interest are genes and functional groups known to affect body patterning, beak morphology, and the immune system, which are important features of diversification and fitness. We show that a combination of mosaic parental inheritance and novel divergence within the hybrid lineage has facilitated the origin and maintenance of an avian hybrid species.
杂交在自然界中很普遍，在某些情况下，可能会导致新的杂交物种的形成。我们通过对杂交意大利麻雀及其祖先的全基因组分析来研究这一尚未完全了解的过程的遗传基础。我们发现，在杂交基因组中，每个亲本物种的贡献总体上是平衡的，但存在异质性，并在杂交物种中发现了一些新的分化区域，这些区域表现出与平衡选择一致的信号。高分化区域不成比例地位于 Z 染色体上，并在与关键特征相关的基因网络中过度表达，这些特征可能与生殖障碍和/或物种特异性适应有关。特别有趣的是那些已知影响身体图案、喙形态和免疫系统的基因和功能群，这些是多样化和适应性的重要特征。我们表明，杂交谱系中镶嵌式亲本遗传和新的分化的结合促进了一个鸟类杂交物种的起源和维持。
