Data from: Admixture mapping identifies introgressed genomic regions in North American canids

Hybrid zones typically contain novel gene combinations that can be tested by natural selection in a unique genetic context. Parental haplotypes that increase fitness can introgress beyond the hybrid zone, into the range of parental species. We used the Affymetrix canine SNP genotyping array to identify genomic regions tagged by multiple ancestry informative markers that are more frequent in an admixed population than expected. We surveyed a hybrid zone formed in the last 100 years as coyotes expanded their range into eastern North America. Concomitant with expansion, coyotes hybridized with wolves and some populations became more wolflike, such that coyotes in the northeast have the largest body size of any coyote population. Using a set of 3102 ancestry informative markers, we identified 60 differentially introgressed regions in 44 canines across this admixture zone. These regions are characterized by an excess of exogenous ancestry and, in northeastern coyotes, are enriched for genes affecting body size and skeletal proportions. Further, introgressed wolf-derived alleles have penetrated into Southern US coyote populations. Because no wolves currently exist in this area, these alleles are unlikely to have originated from recent hybridization. Instead, they probably originated from intraspecific gene flow or ancient admixture. We show that grey wolf and coyote admixture has far-reaching effects and, in addition to phenotypically transforming admixed populations, allows for the differential movement of alleles from different parental species to be tested in new genomic backgrounds.

杂交带通常携带有新颖的基因组合，这类组合可在独特的遗传背景下接受自然选择的筛选。可提升适应度的亲本单倍型可越过杂交带发生基因渐渗，进入亲本物种的分布范围。
我们使用昂飞（Affymetrix）犬类单核苷酸多态性（Single Nucleotide Polymorphism, SNP）基因分型芯片，来识别被多个祖先信息标记（Ancestry Informative Markers）所标记的基因组区域——这类区域在混合种群中的出现频率高于预期值。
我们对一个形成于过去百年间的杂交带开展了调查：当时郊狼的分布范围扩张至北美东部。伴随分布范围扩张，郊狼与灰狼发生了杂交，部分种群的类狼特征愈发显著，以致北美东北部的郊狼成为所有郊狼种群中体型最大的类群。
我们借助一套包含3102个祖先信息标记的标记集，在该杂交带的44只犬科动物中鉴定出了60个差异渐渗区域。这些区域以携带过量外来祖先血统为特征，且在北美东北部的郊狼体内，这类区域富集了与体型及骨骼比例相关的基因。
进一步研究发现，渐渗的狼源等位基因已经扩散至美国南部的郊狼种群中。由于该区域目前已无灰狼分布，这些等位基因不太可能源自近期的杂交事件。取而代之的是，它们大概率源于种内基因流或古老的种群混合事件。
本研究证实，灰狼与郊狼的杂交效应波及范围广泛：其不仅会使混合种群发生表型层面的转变，还能让来自不同亲本物种的等位基因在全新的基因组背景下完成差异化流动并接受选择检验。