Rare hybrid solves “genetic problem” of linked plumage traits
Rare hybrid solves “genetic problem” of linked plumage traits
复制标题
稀有杂交解决了相关羽毛性状的“遗传问题”
DOI：
10.1002/ecy.3424
复制
发表时间：
2021
期刊：
影响因子：
4.8
通讯作者：
Toews, David P. L.
中科院分区：
文献类型：
--
作者：
Baiz, Marcella D.;Wood, Andrew W.;Toews, David P. L.
生态学，102（10），2021，e03424© 2021由美国生态学会逐渐被蓝翅莺取代（班尼特等人。2017），表明杂交区的变化可能对塑造它们的进化轨迹很重要。我们于2020年6月8日在美国宾夕法尼亚州亨廷顿县（40.651635 N，77.942584 W）的一个同时具有亲本表型和“典型”（匹配）杂交种的地区偶然观察到这种不匹配的杂交种。我们用录好的金翅莺的歌声来引诱个体进入雾网。捕获后，我们使用Gill（1980）的评分标准评估其羽毛，并添加以下特征：面具，眼线和胡子颜色。我们还将美国地质调查局的铝带固定在鸟身上（带号283030117），并从肱静脉中获得血液样本进行遗传分析。除了喉羽和眼线羽外，我们对不匹配杂交种的所有羽毛性状进行了评估，并对金翅莺进行了评分（附录S1：表S1）。错配的杂种表现出35的羽毛得分，其中最大得分（38）代表金翅莺羽毛表型，最小得分（0）代表蓝翅莺羽毛表型。在Vermivora杂种中，羽毛得分与混合物的遗传得分密切相关（Toews et al 2016），因此不匹配的杂种不太可能是早代杂种，但可能是多代回交到金翅莺的结果。由于错配的杂交种主要表现出金翅莺的羽毛特征（和可能的遗传背景），但共享蓝翅莺的非黑色素喉片，我们推断，通过量化该杂交种基因组中亲本物种的祖先过渡，可以鉴定与喉片分离的面罩背后的基因组区域。我们提取了错配的杂交体的DNA，并按照Toews等人描述的方法使用全基因组重测序。（2016）通过将序列与黄腰柳莺基因组组装（NCBI登录号PRJNA 325157; Baiz et al. 2021）进行比对，定量ASIP（亲本物种表现出固定差异的区域）周围的基因组变异。然后，我们比较了基因型在这一地区的错配杂交的基因型匹配的杂交和亲本个体先前测序的Toews等。（2016）和Baiz et al.（2020年）。对于错配的杂交体，我们获得了4700万个配对读数，导致20号染色体上的109个覆盖率。与我们之前的工作（Baiz et al. 2020）一致，我们确定了ASIP上游约10 kb的区域，其中表现出黑喉的杂交种与金翅莺共享祖先（即图2中的“匹配杂交种”）。在该区域内，我们鉴定了8个单核苷酸多态性（SNP）（在4，247，547 bp-4，252，746 bp之间），其中黑喉个体对金翅等位基因是纯合的，并且与该性状的纯合隐性遗传一致（Parkes 1951），平喉个体对蓝翅等位基因是杂合或纯合的（图2b）。我们认为，这5-kb区域的SNPs可能是莺ASIP喉色基因启动子的一部分。此外，与所有的黑喉鸟不同，错配的杂交种在这个假定的启动子区域的所有SNP几乎都是均匀杂合的。a B金翅莺蓝翅莺
Ecology, 102 (10), 2021, e03424© 2021 by the Ecological Society of America gradual replacement by Blue-winged Warblers (Bennett et al. 2017), suggest the shifting hybrid zones may be important in shaping their evolutionary trajectories. We opportunistically observed this mismatched hybrid on 8 June 2020 in Huntingdon County, Pennsylvania USA (40.651635 N, 77.942584 W), within a region that has both parental phenotypes and “typical”(matched) hybrids. We used a recorded Golden-winged Warbler song playback to lure the individual into a mist net. Upon capture, we assessed its plumage using the scoring criteria of Gill (1980) with the addition of the following traits: mask, eyeline, and mustache color. We also affixed a USGS aluminum band to the bird (band no. 283030117) and attained a blood sample from the brachial vein for genetic analysis. With the exception of throat and eyeline plumage, we assigned Golden-winged Warbler scores in all of the plumage traits assessed for the mismatched hybrid (Appendix S1: Table S1). The mismatched hybrid exhibits a plumage score of 35, where the maximum score (38) represents the Golden-winged Warbler plumage phenotype and the minimum score (0) represents the Blue-winged Warbler plumage phenotype. In Vermivora hybrids, plumage scores are closely correlated with genetic scores of admixture (Toews et al 2016), so the mismatched hybrid is not likely an early-generation hybrid, but likely a result of multiple generations of backcrossing into Golden-winged Warblers. Because the mismatched hybrid exhibits mostly Golden-winged Warbler plumage traits (and likely genetic background), but shares the non-melanated throat patch of Blue-winged Warblers, we reasoned that it may be possible to identify the genomic region underlying the face mask separate from the throat patch by quantifying transitions in ancestry from the parental species in the genome of this hybrid. We extracted the mismatched hybrid’s DNA and used whole-genome resequencing following the approach described in Toews et al.(2016) to quantify genomic variation around ASIP, a region where parental species exhibit fixed differences, by aligning sequences to the Yellow-rumped Warbler genome assembly (NCBI accession PRJNA325157; Baiz et al. 2021). We then compared genotypes in this region for the mismatched hybrid to genotypes from matched hybrids and parental individuals previously sequenced in Toews et al.(2016) and Baiz et al.(2020). For the mismatched hybrid, we obtained 47 million paired reads, resulting in 109 coverage across chromosome 20. Consistent with our previous work (Baiz et al. 2020), we identified an~ 10-kb region upstream of ASIP where hybrids that exhibit a black throat share ancestry with Golden-winged Warblers (ie,“matched hybrids” in Fig. 2). Within this region, we identified eight single nucleotide polymorphisms (SNPs)(between 4,247,547 bp–4,252,746 bp) where black-throated individuals are homozygous for the golden-winged allele and, consistent with homozygous recessive inheritance of the trait (Parkes 1951), plain-throated individuals are either heterozygous or homozygous for the blue-winged allele (Fig. 2b). We posit that the SNPs that with this 5-kb region are likely part of the warbler ASIP throat-color gene promoter. Moreover, unlike all black-throated birds, the mismatched hybrid was nearly uniformly heterozygous for all SNPs in this presumed promoter region. a b Golden-winged warbler Blue-winged warbler