Araripe L O, Tao Y, Lemos B
Laboratório de Biologia Molecular de Insetos, Fundação Oswaldo Cruz, IOC, Rio de Janeiro, Brasil.
Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, USA.
Heredity (Edinb). 2016 Jun;116(6):516-22. doi: 10.1038/hdy.2016.11. Epub 2016 Mar 16.
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染色体在物种内部和物种之间都表现出群体差异。群体内部的共同进化预计会在Y染色体与基因组其他部分之间产生适应性相互作用。一个后果是，来自不同群体的Y染色体可能会破坏共同进化的遗传元件之间的和谐相互作用，导致雄性生育力下降、不育或无法存活。在这里，我们研究了“异源Y染色体”对携带在拟果蝇背景中渗入的毛里求斯果蝇纯合区域的杂交雄性生育力的影响。为了检测Y染色体与常染色体之间的相互作用，这种相互作用在单一物种的常染色体背景中可能不会被注意到，我们构建了涉及三个姐妹物种的杂交基因型：拟果蝇、毛里求斯果蝇和塞舌尔果蝇。这些工程菌株因以下因素而有所不同：(i) Y染色体的物种来源（拟果蝇或塞舌尔果蝇）；(ii) 渗入的毛里求斯果蝇片段在拟果蝇第三条染色体上的位置，以及(iii) 祖父母的基因组背景（拟果蝇的三种基因型）。我们发现Y染色体的物种来源、毛里求斯果蝇片段的身份以及提供染色体的祖父母遗传背景之间存在复杂的相互作用。出乎意料的是，在存在Ysim的情况下，Y染色体与毛里求斯果蝇一个片段的相互作用会大幅降低生育力，而当塞舌尔果蝇的Y染色体来自特定的祖父母基因型时，生育力会部分恢复。尽管常染色体和X连锁基因组大多起源于拟果蝇，但生育力仍得以恢复。这些结果说明了涉及Y染色体的遗传相互作用有多因素基础。我们的研究支持了Y染色体可对生殖隔离的进化做出重大贡献这一假设，并突出了不育在特定基因型组合中的条件性表现。
