Department of Ecosystem and Conservation Sciences, The University of Montana, 32 Campus Drive, Missoula, MT, 59812, USA.
Department of Integrative Biology, University of California, Berkeley, CA, 94720, USA.
Nat Commun. 2017 Nov 17;8(1):1593. doi: 10.1038/s41467-017-01761-4.
Genome evolution is predicted to be rapid following the establishment of new (neo) sex chromosomes, but it is not known if neo-sex chromosome evolution plays an important role in speciation. Here we combine extensive crossing experiments with population and functional genomic data to examine neo-XY chromosome evolution and incipient speciation in the mountain pine beetle. We find a broad continuum of intrinsic incompatibilities in hybrid males that increase in strength with geographic distance between reproductively isolated populations. This striking progression of reproductive isolation is coupled with extensive gene specialization, natural selection, and elevated genetic differentiation on both sex chromosomes. Closely related populations isolated by hybrid male sterility also show fixation of alternative neo-Y haplotypes that differ in structure and male-specific gene content. Our results suggest that neo-sex chromosome evolution can drive rapid functional divergence between closely related populations irrespective of ecological drivers of divergence.
基因组进化预计在新（neo）性染色体建立后会迅速发生，但尚不清楚 neo 性染色体进化是否在物种形成中发挥重要作用。在这里，我们结合广泛的杂交实验以及群体和功能基因组数据，研究了山松甲虫中新 X-Y 染色体的进化和初期物种形成。我们发现杂种雄性中存在广泛的内在不相容性，这种不相容性随着生殖隔离种群之间的地理距离的增加而增强。这种引人注目的生殖隔离进展伴随着广泛的基因特化、自然选择和两个性染色体上的遗传分化。由杂种雄性不育隔离的密切相关的种群也表现出替代的 neo-Y 单倍型的固定，这些单倍型在结构和雄性特异性基因含量上存在差异。我们的结果表明，neo 性染色体进化可以驱动密切相关的种群之间的快速功能分化，而与分化的生态驱动因素无关。
