Vinciguerra Nicholas T, Tsai Whitney L E, Faircloth Brant C, McCormack John E
Moore Laboratory of Zoology, Occidental College, Los Angeles, CA, USA.
Department of Biology, San Diego State University, San Diego, USA.
BMC Res Notes. 2019 Jul 24;12(1):456. doi: 10.1186/s13104-019-4481-z.
Hybrid zones are geographic regions where genetically distinct taxa interbreed, resulting in offspring of mixed ancestry. California Scrub-Jays (Aphelocoma californica) and Woodhouse's Scrub-Jays (A. woodhouseii) come into secondary contact and hybridize in western Nevada. Although previous work investigated divergence and gene flow between these species using a handful of microsatellite markers, the hybrid zone has not been studied using genome-scale markers, providing an opportunity to assess genome-wide introgression, test for a genetic basis for ecomorphological traits, and compare these estimates to those derived from microsatellites.
Using variant sites flanking ultraconserved elements (UCEs), we performed population assignment and quantified hybrid ancestry for 16 individuals across the zone of secondary contact. Our study included 2468 SNPs distributed throughout the genome, allowing discrimination of genetic affinities of hybrid individuals that were similar to estimates from microsatellites. We show a relationship between bill and wing length and the genetic composition of individuals that was not found in prior work using microsatellites, suggesting a genetic basis for these traits. Our analyses demonstrate the utility of UCEs for the analysis of hybrid zones and provide a basis for future studies to identify the genomic architecture of speciation and phenotypic differences between these incipient species.
杂交带是遗传上不同的分类群进行杂交的地理区域，会产生混合血统的后代。加州灌丛松鸦（Aphelocoma californica）和伍德豪斯灌丛松鸦（A. woodhouseii）在内华达州西部发生二次接触并杂交。尽管此前的研究使用少量微卫星标记调查了这些物种之间的分化和基因流动，但尚未使用基因组规模的标记对杂交带进行研究，这为评估全基因组渐渗、测试生态形态特征的遗传基础以及将这些估计值与从微卫星获得的估计值进行比较提供了机会。
利用超保守元件（UCE）侧翼的变异位点，我们对二次接触区域内的16个个体进行了种群归属分析并量化了杂交血统。我们的研究包括分布在整个基因组中的2468个单核苷酸多态性（SNP），能够区分杂交个体的遗传亲缘关系，其结果与微卫星估计值相似。我们发现喙长和翅长与个体的遗传组成之间存在一种此前使用微卫星的研究中未发现的关系，这表明这些性状具有遗传基础。我们的分析证明了UCE在杂交带分析中的实用性，并为未来研究确定这些初始物种之间物种形成的基因组结构和表型差异提供了基础。
