Department of Integrated Biosciences, University of Tokyo, Kashiwa, Japan.
Department of Biological Information, Tokyo Institute of Technology, Meguro-ku, Japan.
Sci Adv. 2018 Apr 18;4(4):eaao5416. doi: 10.1126/sciadv.aao5416. eCollection 2018 Apr.
Batesian mimicry protects animals from predators when mimics resemble distasteful models. The female-limited Batesian mimicry in butterflies is controlled by a supergene locus switching mimetic and nonmimetic forms. In , recent studies revealed that a highly diversified region (HDR) containing (-HDR) constitutes the supergene with dimorphic alleles and is likely maintained by a chromosomal inversion. In the closely related , which exhibits a similar mimicry polymorphism, we performed whole-genome sequence analyses in 11 butterflies, which revealed a nearly identical -HDR containing three genes (, , and ) with dimorphic sequences strictly associated with the mimetic/nonmimetic phenotypes. In addition, expression of these genes, except that of in female hind wings, showed differences correlated with phenotype. The dimorphic -HDR in is maintained without a chromosomal inversion, suggesting that a separate mechanism causes and maintains allelic divergence in these genes. More abundant accumulation of transposable elements and repetitive sequences in the -HDR than in other genomic regions may contribute to the suppression of chromosomal recombination. Gene trees for Dsx, Nach-like, and UXT indicated that mimetic alleles evolved independently in the two species. These results suggest that the genomic region involving the above three genes has repeatedly diverged so that two allelic sequences of this region function as developmental switches for mimicry polymorphism in the two species. The supergene structures revealed here suggest that independent evolutionary processes with different genetic mechanisms have led to parallel evolution of similar female-limited polymorphisms underlying Batesian mimicry in butterflies.
贝氏拟态通过使模拟者与令人不快的模型相似来保护动物免受捕食者的伤害。蝴蝶的雌性限性贝氏拟态由一个超级基因座开关控制，该开关切换模拟和非模拟形式。在 ，最近的研究表明，一个高度多样化的区域（HDR）包含 （-HDR）构成具有二态等位基因的超级基因，并且可能由染色体倒位维持。在密切相关的 ，它表现出类似的拟态多态性，我们对 11 只蝴蝶进行了全基因组序列分析，揭示了一个几乎相同的 -HDR，包含三个基因（ ， ，和 ），具有严格与模拟/非模拟表型相关的二态序列。此外，这些基因的表达，除了雌性后翅中的 外，表现出与表型相关的差异。-HDR 在 中没有染色体倒位维持，表明一个单独的机制导致和维持这些基因的等位基因分歧。-HDR 中的转座元件和重复序列比其他基因组区域更丰富的积累可能有助于抑制染色体重组。Dsx、Nach-like 和 UXT 的基因树表明，模拟等位基因在这两个 物种中独立进化。这些结果表明，涉及上述三个基因的基因组区域已经多次分化，使得该区域的两个等位基因序列在这两个 物种中作为拟态多态性的发育开关发挥作用。揭示的超级基因结构表明，不同遗传机制的独立进化过程导致了蝴蝶中贝氏拟态的类似雌性限性多态性的平行进化。
