doublesex is a mimicry supergene
一些无毒蝴蝶会长出与有毒蝴蝶近似的翅膀图案，对天敌形成“威慑”，这是一种典型拟态。新一期英国《自然》杂志５日在线刊登的一项新研究说，帮助蝴蝶进行拟态的是一种“超级基因”，并非此前认为的由一系列基因共同控制。
美国芝加哥大学等机构的研究人员和印度同行对一种亚洲燕尾蝶开展研究，这种燕尾蝶的雌性有４种翅膀图案，其中３种是模拟其他有毒蝴蝶的翅膀花纹，但该燕尾蝶的雄性则没有翅膀拟态图案。
研究人员让翅膀图案不同的上述雌雄燕尾蝶配对繁衍，对其产下的约５００只燕尾蝶后代进行基因组对比，筛选出有可能与翅膀拟态图案相关的基因。
随后他们综合运用基因组测序、基因表达分析等一系列方法，发现在这些基因中，决定燕尾蝶性别的一种基因才是拟态图案的真正控制者。
研究人员说，如此复杂的拟态现象仅由一种基因控制，这一发现的确令人意外。这项研究有助于了解拟态现象的遗传学基础，研究人员下一步将分析这种“超级基因”发挥作用的具体机制。
（来源：新华网 刘石磊）
Abstract
One of the most striking examples of sexual dimorphism is sex-limited mimicry in butterflies, a phenomenon in which one sex—usually the female—mimics a toxic model species, whereas the other sex displays a different wing pattern. Sex-limited mimicry is phylogenetically widespread in the swallowtail butterfly genus Papilio, in which it is often associated with female mimetic polymorphism. In multiple polymorphic species, the entire wing pattern phenotype is controlled by a single Mendelian ‘supergene. Although theoretical work has explored the evolutionary dynamics of supergene mimicry, there are almost no empirical data that address the critical issue of what a mimicry supergene actually is at a functional level. Using an integrative approach combining genetic and association mapping, transcriptome and genome sequencing, and gene expression analyses, we show that a single gene, doublesex, controls supergene mimicry in Papilio polytes. This is in contrast to the long-held view that supergenes are likely to be controlled by a tightly linked cluster of loci. Analysis of gene expression and DNA sequence variation indicates that isoform expression differences contribute to the functional differences between dsx mimicry alleles, and protein sequence evolution may also have a role. Our results combine elements from different hypotheses for the identity of supergenes, showing that a single gene can switch the entire wing pattern among mimicry phenotypes but may require multiple, tightly linked mutations to do so.
相关链接
doi:10.1038/nature13112
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