6日刊登在《自然》期刊（Nature）的研究報(bào)告指出,，角蟬頭上引人注目的突起物,，其實(shí)是翼狀翅膀，經(jīng)過(guò)2億年演化淘汰后,，又重新長(zhǎng)回來(lái),。專家說(shuō)，這項(xiàng)發(fā)現(xiàn)或許會(huì)震驚昆蟲學(xué)家,，也挑戰(zhàn)昆蟲學(xué)部分根基,。
昆蟲的身體分為頭部、胸部（thorax）和腹部,，地球上所有昆蟲胸部分成3節(jié),，每節(jié)都有2只腳。大部分昆蟲目有2對(duì)翅膀,，一對(duì)在胸部中節(jié),，一對(duì)在后節(jié)。蒼蠅和蚊子只有在后節(jié)有一對(duì)翅膀,，少數(shù)昆蟲,，如大多數(shù)螞蟻則完全沒(méi)有翅膀。胸部第一節(jié)有翅膀的昆蟲,，如今已不存在,，不過(guò)它們的先祖卻有。
研究主筆人,、法國(guó)馬賽魯米尼生物發(fā)展機(jī)構(gòu)的普魯?shù)滥罚˙enjamin Prudhomme）說(shuō),，「3億5000萬(wàn)年前的原始昆蟲身體每節(jié)都有翅膀。我們不曉得是不是用來(lái)飛行,，不過(guò)我們確實(shí)知道,，從化石紀(jì)錄來(lái)看，這些翼狀結(jié)構(gòu)存在于身體每節(jié)上,?！菇?jīng)過(guò)了1億年，昆蟲胸部第一節(jié)和腹部翅膀完全消失,。
不過(guò),，5000多萬(wàn)年后，角蟬發(fā)生了異變,，胸部第一節(jié)出現(xiàn)看起來(lái)像翅膀的東西,。這些分岔的突起物，有些長(zhǎng)得像角,，有些像觸角,，有些像被觸怒的螞蟻，有些則像動(dòng)物糞便,，五花八門,。專家長(zhǎng)久以來(lái)認(rèn)為這些所謂的「安全帽」,，是昆蟲外部甲殼構(gòu)造的延伸。
仔細(xì)觀察角蟬的生長(zhǎng)后,，普魯?shù)滥泛屯掳l(fā)現(xiàn),，這些突起物一開始長(zhǎng)得像一對(duì)芽，附著在兩側(cè),，之后再長(zhǎng)成翼狀物,，期間還會(huì)合并,。演化通常被認(rèn)為是單方向進(jìn)行,，不過(guò)這些翅膀顯示演化有可能繞了一圈重回起點(diǎn)。（生物谷Bioon.com）
生物谷推薦原文出處：
Nature 473, 83–86 (05 May 2011) doi:10.1038/nature09977
Body plan innovation in treehoppers through the evolution of an extra wing-like appendage
Benjamin Prud’homme1, Caroline Minervino1, Mélanie Hocine1, Jessica D. Cande1, A?cha Aouane1, Hélo?se D. Dufour2, Victoria A. Kassner2 & Nicolas Gompel1
Body plans, which characterize the anatomical organization of animal groups of high taxonomic rank1, often evolve by the reduction or loss of appendages (limbs in vertebrates and legs and wings in insects, for example). In contrast, the addition of new features is extremely rare and is thought to be heavily constrained, although the nature of the constraints remains elusive2, 3, 4. Here we show that the treehopper (Membracidae) ‘helmet’ is actually an appendage, a wing serial homologue on the first thoracic segment. This innovation in the insect body plan is an unprecedented situation in 250?Myr of insect evolution. We provide evidence suggesting that the helmet arose by escaping the ancestral repression of wing formation imparted by a member of the Hox gene family, which sculpts the number and pattern of appendages along the body axis5, 6, 7, 8. Moreover, we propose that the exceptional morphological diversification of the helmet was possible because, in contrast to the wings, it escaped the stringent functional requirements imposed by flight. This example illustrates how complex morphological structures can arise by the expression of ancestral developmental potentials and fuel the morphological diversification of an evolutionary lineage.
