Evaluating the impact of the introgression of Iberian wild goats (Capra pyrenaica) by domestic goats (Capra hircus) from a genome-wide perspective

Iberian wild goats (<i>Capra pyrenaica</i>, also known as Iberian ibex, Spanish ibex, and Spanish wild goat) underwent strong genetic bottlenecks during the 19^th and 20^th centuries due to overhunting and habitat destruction. From the 1970s to 1990s, augmentation translocations were frequently carried out to restock Iberian wild goat populations (very often with hunting purposes), but they were not systematically planned or recorded. On the other hand, recent data suggest the occurrence of hybridization events between Iberian wild goats and domestic goats (<i>Capra hircus</i>). Augmentation translocations and interspecific hybridization might have contributed to increase the diversity of Iberian wild goats. With the aim of investigating this issue, we have genotyped 118 Iberian wild goats from Tortosa-Beceite, Sierra Nevada, Muela de Cortés, Gredos, Batuecas and, Ordesa and Monte Perdido by using the Goat SNP50 BeadChip (Illumina). The analysis of genotypic data indicated that Iberian wild goat populations are strongly differentiated and display low diversity. Only three Iberian wild goats out from 118 show genomic signatures of mixed ancestry, a result consistent with a scenario in which past augmentation translocations have had a limited impact on the diversity of Iberian wild goats. Besides, we have detected eight Iberian wild goats from Tortosa-Beceite with signs of domestic goat introgression. Although rare, hybridization with domestic goats could become a potential threat to the genetic integrity of Iberian wild goats, hence measures should be taken to avoid the presence of uncontrolled herds of domestic or feral goats in mountainous areas inhabited by this iconic wild ungulate.<br>

伊比利亚野山羊（Iberian wild goats，学名*Capra pyrenaica*，又称伊比利亚羱羊、西班牙羱羊及西班牙野山羊）在19世纪与20世纪期间，因过度狩猎与栖息地破坏，经历了强烈的遗传瓶颈（genetic bottleneck）事件。1970年代至1990年代，为补充伊比利亚野山羊种群（多数出于狩猎目的），人们频繁开展了辅助引种增容（augmentation translocations）操作，但此类活动并未得到系统规划或记录。
另一方面，近期数据显示伊比利亚野山羊与家山羊（*Capra hircus*）之间存在种间杂交事件。辅助引种增容与种间杂交或许有助于提升伊比利亚野山羊的遗传多样性。
为探究这一问题，我们利用山羊SNP50基因分型芯片（Goat SNP50 BeadChip，Illumina公司），对采自托尔托萨-贝塞特、内华达山脉、科尔特斯山、格雷多斯山脉、巴杜埃卡斯以及奥尔德萨和蒙特佩尔迪多的118只伊比利亚野山羊进行了基因分型。
基因型数据分析结果表明，伊比利亚野山羊种群分化程度极高且遗传多样性偏低。118份样本中仅3只呈现出混合祖先的基因组特征，这一结果与过往辅助引种增容对伊比利亚野山羊多样性影响有限的情形相符。此外，我们在托尔托萨-贝塞特种群中检测到8只伊比利亚野山羊带有家山羊的基因渐渗（introgression）信号。
尽管此类杂交事件较为罕见，但与家山羊的杂交仍可能对伊比利亚野山羊的遗传完整性（genetic integrity）构成潜在威胁，因此应采取相关措施，避免在这一标志性野生有蹄类动物的栖息山区出现未受管控的家山羊或野生化山羊种群。