Low levels of hybridization across two contact zones among three species of woodpeckers (Sphyrapicus sapsuckers)

Three species of closely related woodpeckers (sapsuckers; Sphyrapicus) hybridize where they come into contact, presenting a rare ‘λ‐shape’ meeting of hybrid zones. Two of the three arms of this hybrid zone are located on either side of the Interior Plateau of British Columbia, Canada bordering the foothills of the Coast Mountains and the Rocky Mountains. The third arm is located in the eastern foothills of the Rocky Mountains. The zones of hybridization present high variability of phenotypes and alleles in relatively small areas and provide an opportunity to examine levels of reproductive isolation between the taxa involved. We examined phenotypes (morphometric traits and plumage) and genotypes of 175 live birds across the two hybrid zones. We used the Genotyping By Sequencing (GBS) method to identify 180 partially diagnostic single nucleotide polymorphisms (SNPs) to generate a genetic hybrid index (GHI) for each bird. Phenotypically diverged S. ruber and S. nuchalis are genetically clo...

三种亲缘关系密切的啄木鸟（吸汁啄木鸟属（Sphyrapicus））在种群接触区域发生杂交，呈现出罕见的λ形杂交带交汇格局。该杂交带的三条分支中，有两条位于加拿大不列颠哥伦比亚省内陆高原的两侧，分别毗邻海岸山脉山麓与落基山脉山麓；第三条分支则位于落基山脉东部山麓。此类杂交带在相对狭小的区域内便展现出极高的表型与等位基因变异度，为探究相关类群间的生殖隔离水平提供了绝佳研究契机。我们对两处杂交带中的175只活体鸟类开展了表型（形态测量性状与羽色）及基因型分析：采用测序分型（Genotyping By Sequencing，GBS）技术，鉴定出180个具备部分诊断价值的单核苷酸多态性（single nucleotide polymorphisms，SNPs）位点，以此为每只个体构建遗传杂交指数（genetic hybrid index，GHI）。表型分化显著的红吸汁啄木鸟（S. ruber）与红颈吸汁啄木鸟（S. nuchalis）在遗传层面却较为接近……