Reduced Introgression of Sex Chromosome Markers in the Mexican Howler Monkey (Alouatta palliata x A-pigra) Hybrid Zone
Reduced Introgression of Sex Chromosome Markers in the Mexican Howler Monkey (Alouatta palliata x A-pigra) Hybrid Zone
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DOI：
10.1007/s10764-018-0056-4
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发表时间：
2019-02-01
影响因子：
2.5
通讯作者：
Canales-Espinosa, Domingo
中科院分区：
文献类型：
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作者：
Cortes-Ortiz, Liliana;Nidiffer, Marcella D.;Canales-Espinosa, Domingo
种间杂交允许等位基因从一个基因组向另一个基因组的渐渗或移动。虽然一些基因组区域在杂交过程中自由交换等位基因，但与生殖隔离相关的基因座不会混合。在许多模式生物中，由于存在与杂种不育或不活力相关的多个基因座（“大X效应”），与常染色体相比，X染色体显示出有限的渐渗。同样，如果产生杂种，异配生殖通常是不能存活或不育的，这一模式被称为哈勒定律。我们分析了两种吼猴（Alouatta palliata和A. pigra），在墨西哥南部形成一个自然的杂交区，以评估是否大的X效应和Hallantis的规则影响这些姐妹物种之间的杂交结果。为了鉴定杂交区中每个个体的混合物水平（N=254），我们分析了在杂交区外取样的个体（109 A. pigra和39 A. palliata）来确定亲本物种的等位基因频率，并基于核标记估计杂种指数。然后，我们使用杂交区中的个体进行了无性系分析，以确定每个位点的基因渗入模式。我们的分析表明，虽然混合区是双峰（没有已知的F1和最近几代杂交种）和相当狭窄，有广泛的基因渗入在两个方向，有一个大的混合个人在混合区。线粒体和大多数常染色体标记显示双向渐渗，但有些偏向渐渗向一个物种或其他。性染色体上的所有标记和一些常染色体标记均表现出高度限制的基因渗入。这种模式是一致的假设，性染色体的生殖隔离作出不成比例的贡献，我们的研究结果拓宽了这些模式在动物类群的分类代表性。
Interspecific hybridization allows the introgression or movement of alleles from one genome to another. While some genomic regions freely exchange alleles during hybridization, loci associated with reproductive isolation do not intermix. In many model organisms, the X chromosome displays limited introgression compared to autosomes owing to the presence of multiple loci associated with hybrid sterility or inviability (the "large X-effect"). Similarly, if hybrids are produced, the heterogametic sex is usually inviable or sterile, a pattern known as Haldane's rule. We analyzed the patterns of introgression of genetic markers located in the mitochondrial (control region) and nuclear (autosomal microsatellites and sex chromosome genes) genomes of two howler monkey species (Alouatta palliata and A. pigra) that form a natural hybrid zone in southern Mexico, to evaluate whether the large X-effect and Haldane's rule affect the outcomes of hybridization between these sister species. To identify the level of admixture of each individual in the hybrid zone (N=254) we analyzed individuals sampled outside the hybrid zone (109 A. pigra and 39 A. palliata) to determine allele frequencies of parental species and estimated a hybrid index based on nuclear markers. We then performed a cline analysis using individuals in the hybrid zone to determine patterns of introgression for each locus. Our analyses show that although the hybrid zone is bimodal (with no known F1 s and few recent generation hybrids) and quite narrow, there has been extensive introgression in both directions, and there is a large array of admixed individuals in the hybrid zone. Mitochondrial and most autosomal markers showed bidirectional introgression, but some had biased introgression toward one species or the other. All markers on the sex chromosomes and a few autosomal markers showed highly restricted introgression. This pattern is consistent with the hypothesis that the sex chromosomes make a disproportionate contribution to reproductive isolation, and our results broaden the taxonomic representation of these patterns across animal taxa.