一個(gè)與人類語(yǔ)言進(jìn)化相關(guān)的基因可能同時(shí)幫助蝙蝠喊出了自己的聲音。根據(jù)一項(xiàng)新的研究,，為了尋找獵物及躲避障礙物,，不同種類的蝙蝠都會(huì)發(fā)出高頻尖叫聲，無(wú)一例外,，它們都攜帶有一種高度變異的FOXP2基因,，這意味著，這種基因在蝙蝠體內(nèi)的遺傳變化促進(jìn)了其在功能上的進(jìn)化,。
FOXP2所編碼的蛋白質(zhì)似乎能夠影響嘴部運(yùn)動(dòng)和語(yǔ)言能力之間的協(xié)調(diào)性,。2001年，這種基因第一次引起了科學(xué)家的關(guān)注——人們發(fā)現(xiàn),，它與說(shuō)話和語(yǔ)言紊亂有關(guān),。一年后，研究人員再度發(fā)現(xiàn),，F(xiàn)OXP2很可能在語(yǔ)言的進(jìn)化中扮演了一個(gè)重要角色,。這種基因同時(shí)也對(duì)小鼠產(chǎn)生了影響：那些沒(méi)有FOXP2的小鼠彼此之間無(wú)法利用超聲波進(jìn)行交流。
英國(guó)倫敦大學(xué)女王學(xué)院的遺傳學(xué)家Stephen Rossiter和他的同事于是尋思,，蝙蝠的進(jìn)化是否也依賴于FOXP2基因,。相形之下，這些哺乳動(dòng)物使人類的會(huì)話多少顯得有些小兒科——在一種名為回聲定位的行為中,，蝙蝠必須使鼻,、口、耳和喉協(xié)同工作,，以便發(fā)出叫聲和接收回聲,。所有這些過(guò)程都是在飛行過(guò)程中機(jī)動(dòng)完成的,，而蝙蝠也正是依靠這些信號(hào)為自己導(dǎo)航。Rossiter與中國(guó)上海華東師范大學(xué)的李鋼（音譯）和張樹(shù)義及其同事合作,，對(duì)13只蝙蝠（它們分屬6類蝙蝠）所攜帶的FOXP2基因進(jìn)行了測(cè)序,，這些蝙蝠有的使用回聲定位，有的則沒(méi)有這種技能,。研究人員同時(shí)在其他23種哺乳動(dòng)物——其中包括鴨嘴獸——以及2種鳥(niǎo)類和1種爬行動(dòng)物體內(nèi)尋找這種基因,。
研究人員發(fā)現(xiàn)，與其他動(dòng)物相比,，蝙蝠的FOXP2基因序列所產(chǎn)生的突變是前者的2倍,，這意味著迅速的進(jìn)化。此外,，親緣關(guān)系較近的蝙蝠——它們具有類似的超聲波接受能力——趨向于發(fā)生相同的突變,。同時(shí)，這些遺傳變化并不會(huì)被那些親緣關(guān)系較遠(yuǎn)或不依靠回聲定位的蝙蝠所共享,。某些蝙蝠具有與導(dǎo)致人類語(yǔ)言障礙的變異類似的遺傳突變,。Rossiter指出：“我們的發(fā)現(xiàn)表明，F(xiàn)OXP2基因在蝙蝠的回聲定位能力的進(jìn)化與多樣化過(guò)程中扮演了一個(gè)至關(guān)重要的角色,。”
這一結(jié)論對(duì)于英國(guó)牛津大學(xué)的神經(jīng)遺傳學(xué)家Simon Fisher具有重要意義,，他曾發(fā)現(xiàn)FOXP2變異與語(yǔ)言紊亂之間存在聯(lián)系。Fisher表示,，這一研究結(jié)果支持了這樣一種假設(shè),，即源自動(dòng)物祖先發(fā)聲與運(yùn)動(dòng)系統(tǒng)的說(shuō)話和語(yǔ)言的進(jìn)化，隨著時(shí)間流逝被重新排列,，且變得更為復(fù)雜,。但德國(guó)柏林自由大學(xué)的神經(jīng)生物學(xué)家Constance Scharff強(qiáng)調(diào)，對(duì)于FOXP2基因在回聲定位中扮演的角色還需要進(jìn)行功能性研究,，例如搞清敲掉這一基因后會(huì)產(chǎn)生什么樣的后果,。（科學(xué)時(shí)報(bào)）
原始出處:
Received: March 18, 2007; Accepted: August 15, 2007; Published: September 19, 2007
Accelerated FoxP2 Evolution in Echolocating Bats
Gang Li1,2, Jinhong Wang1, Stephen J. Rossiter3*, Gareth Jones4, Shuyi Zhang1*
1 School of Life Science, East China Normal University, Shanghai, China, 2 Institute of Zoology and Graduate University, Chinese Academy of Sciences, Beijing, China, 3 School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom, 4 School of Biological Sciences, University of Bristol, Bristol, United Kingdom
Abstract
FOXP2 is a transcription factor implicated in the development and neural control of orofacial coordination, particularly with respect to vocalisation. Observations that orthologues show almost no variation across vertebrates yet differ by two amino acids between humans and chimpanzees have led to speculation that recent evolutionary changes might relate to the emergence of language. Echolocating bats face especially challenging sensorimotor demands, using vocal signals for orientation and often for prey capture. To determine whether mutations in the FoxP2 gene could be associated with echolocation, we sequenced FoxP2 from echolocating and non-echolocating bats as well as a range of other mammal species. We found that contrary to previous reports, FoxP2 is not highly conserved across all nonhuman mammals but is extremely diverse in echolocating bats. We detected divergent selection (a change in selective pressure) at FoxP2 between bats with contrasting sonar systems, suggesting the intriguing possibility of a role for FoxP2 in the evolution and development of echolocation. We speculate that observed accelerated evolution of FoxP2 in bats supports a previously proposed function in sensorimotor coordination.
Figure 1. Radial phylogenetic tree showing relative rates of non-synonymous evolution among 35 eutherian mammals, including 13 bats.
Bats species are given as italicised binomial names. Branch lengths based on maximum-likelihood estimates of non-synonymous substitutions along 1995 bp of the FoxP2 gene are superimposed onto a cladogram based on published trees [31], [33], [34]. Bat lineages are coloured to show the echolocating Yinpterochiroptera (blue) that mostly possess high duty constant frequency (CF) calls with at least partial Doppler shift compensation, the Yangochiroptera (orange) that mostly possess low duty cycle calls, as well as the absence of laryngeal echolocation in Yinpterochiroptera fruit bats (violet). The taxa analysed are listed in the Methods and in table S2
全文鏈接：http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0000900
