Data from: Interspecific Y chromosome variation is sufficient to rescue hybrid male sterility and is influenced by the grandparental origin of the chromosomes

Y chromosomes display population variation within and between species. Co-evolution within populations is expected to produce adaptive interactions between Y chromosomes and the rest of the genome. One consequence is that Y chromosomes from disparate populations could disrupt harmonious interactions between co-evolved genetic elements and result in reduced male fertility, sterility or inviability. Here we address the contribution of ‘heterospecific Y chromosomes’ to fertility in hybrid males carrying a homozygous region of Drosophila mauritiana introgressed in the Drosophila simulans background. In order to detect Y chromosome–autosome interactions, which may go unnoticed in a single-species background of autosomes, we constructed hybrid genotypes involving three sister species: Drosophila simulans, D. mauritiana, and D. sechellia. These engineered strains varied due to: (i) species origin of the Y chromosome (D. simulans or D. sechellia); (ii) location of the introgressed D. mauritiana segment on the D. simulans third chromosome, and (iii) grandparental genomic background (three genotypes of D. simulans). We find complex interactions between the species origin of the Y chromosome, the identity of the D. mauritiana segment and the grandparental genetic background donating the chromosomes. Unexpectedly, the interaction of the Y chromosome and one segment of D. mauritiana drastically reduced fertility in the presence of Ysim, whereas the fertility is partially rescued by the Y chromosome of D. sechellia when it descends from a specific grandparental genotype. The restoration of fertility occurs in spite of an autosomal and X-linked genome that is mostly of D. simulans origin. These results illustrate the multifactorial basis of genetic interactions involving the Y chromosome. Our study supports the hypothesis that the Y chromosome can contribute significantly to the evolution of reproductive isolation and highlights the conditional manifestation of infertility in specific genotypic combinations.

Y染色体在物种内部及物种间均展现出种群水平的遗传变异。种群内的协同进化理论上会促成Y染色体与基因组其余组分间的适应性互作，其后果之一是：来源各异的Y染色体可能破坏协同进化的遗传元件间的和谐互作，进而导致雄性生育力下降、不育甚至致死。
本研究针对异种Y染色体（heterospecific Y chromosomes）对携带渐渗入黑腹果蝇（Drosophila simulans）遗传背景的纯合毛里求斯果蝇（Drosophila mauritiana）片段的杂交雄性个体生育力的影响展开探究。
为了检测常染色体单一物种背景下可能被忽略的Y染色体-常染色体互作，我们构建了涉及3个近缘物种的杂交基因型：黑腹果蝇（Drosophila simulans）、毛里求斯果蝇（Drosophila mauritiana）以及塞舌尔果蝇（Drosophila sechellia）。这些工程化菌株的差异来源于三个维度：(i) Y染色体的物种来源（黑腹果蝇或塞舌尔果蝇）；(ii) 渐渗的毛里求斯果蝇片段在黑腹果蝇第三号染色体上的定位；(iii) 祖代亲本的基因组背景（3种黑腹果蝇基因型）。
我们发现Y染色体的物种来源、毛里求斯果蝇片段的类型以及提供染色体的祖代遗传背景三者间存在复杂的互作关系。令人意外的是，当携带黑腹果蝇来源的Y染色体（Y_sim）时，Y染色体与某一段毛里求斯果蝇片段的互作会大幅降低生育力；而当塞舌尔果蝇Y染色体来自特定祖代基因型时，可部分挽救该生育缺陷。尽管该杂交个体的常染色体与X染色体组主要来源于黑腹果蝇，生育力仍得到了恢复。
上述结果阐明了涉及Y染色体的遗传互作的多因子基础。本研究支持“Y染色体可显著推动生殖隔离演化”这一假说，并凸显了不育表型在特定基因型组合下的条件依赖性。