自然界中，不少蝴蝶掌握借助“擬態(tài)”躲避天敵的本領(lǐng),。一項(xiàng)最新研究發(fā)現(xiàn)，蝴蝶的擬態(tài)功能由其體內(nèi)的“超級(jí)基因簇”決定。
英法兩國(guó)研究人員在8月份的《自然》雜志上發(fā)表論文說(shuō),，他們選取了一種生長(zhǎng)在亞馬遜熱帶雨林地區(qū)的釉蛺蝶進(jìn)行研究。這種蝴蝶能通過(guò)改變翅膀花紋,，“偽裝”成那些味道不佳的蝴蝶,，從而躲過(guò)鳥(niǎo)類的捕食,。
研究人員在分析該種蝴蝶體內(nèi)的染色體序列后發(fā)現(xiàn),，一種染色體內(nèi)部存在多種變異,，各變異組合形成了“超級(jí)基因簇”,，最終決定著擬態(tài)的花紋,。
參與研究的法國(guó)自然歷史博物館馬蒂厄·若龍博士形象地用“變形金剛”來(lái)解釋這個(gè)基因簇的作用，他說(shuō),，蝴蝶可謂昆蟲(chóng)世界的變形金剛，經(jīng)過(guò)簡(jiǎn)單的基因切換組合就可實(shí)現(xiàn)擬態(tài),。
此外，研究人員表示,，“超級(jí)基因簇”同樣存在于飛蛾等其他昆蟲(chóng)體內(nèi),，使它們既可模仿其他同類,，又能模仿周圍環(huán)境,。(生物谷 Bioon.com)
doi:10.1038/nature10341
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Chromosomal rearrangements maintain a polymorphic supergene controlling butterfly mimicry
Mathieu Joron; Lise Frezal; Robert T. Jones; Nicola L. Chamberlain; Siu F. Lee; Christoph R. Haag; Annabel Whibley; Michel Becuwe; Simon W. Baxter; Laura Ferguson; Paul A. Wilkinson; Camilo Salazar; Claire Davidson; Richard Clark; Michael A. Quail; Helen Beasley; Rebecca Glithero; Christine Lloyd; Sarah Sims; Matthew C. Jones; Jane Rogers; Chris D. Jiggins; Richard H. ffrench-Constant
Supergenes are tight clusters of loci that facilitate the co-segregation of adaptive variation, providing integrated control of complex adaptive phenotypes1. Polymorphic supergenes, in which specific combinations of traits are maintained within a single population, were first described for ‘pin’ and ‘thrum’ floral types in Primula1 and Fagopyrum2, but classic examples are also found in insect mimicry3, 4, 5 and snail morphology6. Understanding the evolutionary mechanisms that generate these co-adapted gene sets, as well as the mode of limiting the production of unfit recombinant forms, remains a substantial challenge7, 8, 9, 10. Here we show that individual wing-pattern morphs in the polymorphic mimetic butterfly Heliconius numata are associated with different genomic rearrangements at the supergene locus P. These rearrangements tighten the genetic linkage between at least two colour-pattern loci that are known to recombine in closely related species9, 10, 11, with complete suppression of recombination being observed in experimental crosses across a 400-kilobase interval containing at least 18 genes. In natural populations, notable patterns of linkage disequilibrium (LD) are observed across the entire P region. The resulting divergent haplotype clades and inversion breakpoints are found in complete association with wing-pattern morphs. Our results indicate that allelic combinations at known wing-patterning loci have become locked together in a polymorphic rearrangement at the P locus, forming a supergene that acts as a simple switch between complex adaptive phenotypes found in sympatry. These findings highlight how genomic rearrangements can have a central role in the coexistence of adaptive phenotypes involving several genes acting in concert, by locally limiting recombination and gene flow.
