Genetic rescue of an endangered domestic animal through outcrossing with closely related breeds: a case study of the Norwegian Lundehund

Genetic rescue, outcrossing with individuals from a related population, is used to augment genetic diversity in populations threatened by severe inbreeding and extinction. The endangered Norwegian Lundehund dog (henceforth Lundehund) underwent at least two severe bottlenecks in the 1940s and 1960s that each left only five inbred dogs, and the approximately 1500 dogs remaining world-wide today appear to descend from only two individuals. The Lundehund has a high prevalence of a gastrointestinal disease, to which all remaining dogs may be predisposed. Outcrossing is currently performed with three Nordic Spitz breeds: Norwegian Buhund, Icelandic Sheepdog, and Norrbottenspets. Examination of single nucleotide polymorphism (SNP) genotypes based on 165K loci in 48 dogs from the four breeds revealed substantially lower genetic diversity for the Lundehund (HE 0.035) than for other breeds (HE 0.209-0.284). Analyses of genetic structure with 16K linkage disequilibrium-pruned SNPs showed four dist...遗传拯救（Genetic rescue）指通过与近缘种群的个体开展异交，以提升受严重近交与灭绝威胁的种群的遗传多样性。濒危的挪威伦德猎犬（Norwegian Lundehund，下文简称伦德猎犬）在20世纪40年代与60年代至少经历了两次严重的种群瓶颈，每次瓶颈后仅剩余5只近交犬只，而目前全球尚存的约1500只伦德猎犬均疑似仅由2只个体繁衍而来。伦德猎犬群体中胃肠道疾病的患病率极高，所有现存个体均可能对该疾病存在易感倾向。当前科研人员通过与3种北欧斯皮茨犬品种——挪威布哈德犬（Norwegian Buhund）、冰岛牧羊犬（Icelandic Sheepdog）以及诺波特尼斯庇茨犬（Norrbottenspets）——进行异交来实施遗传拯救。对来自上述4个犬品种的48只个体的16.5万个基因座单核苷酸多态性（Single Nucleotide Polymorphism, SNP）基因型进行检测后发现，伦德猎犬的遗传多样性（期望杂合度Expected Heterozygosity, HE=0.035）显著低于其他3个品种（期望杂合度HE为0.209~0.284）。基于1.6万个经过连锁不平衡筛选的单核苷酸多态性位点开展的遗传结构分析结果显示，可分为4个明显的（原文至此未完成）。