北京時(shí)間7月14日消息,,據(jù)英國(guó)《每日郵報(bào)》報(bào)道,經(jīng)過(guò)長(zhǎng)達(dá)幾個(gè)世紀(jì)的激烈爭(zhēng)論,,科學(xué)家最終發(fā)現(xiàn)了“動(dòng)物為什么會(huì)有性行為”的答案,。研究人員稱(chēng),它們通過(guò)這種方式繁殖的后代對(duì)寄生蟲(chóng)的抵抗力更強(qiáng),。相關(guān)研究發(fā)表在近日出版的《科學(xué)》雜志上,。
異體受精有助于保護(hù)這種動(dòng)物,令它們?cè)谂c天敵一起進(jìn)化的過(guò)程中,,比“敵人”優(yōu)先一步,。在這項(xiàng)研究中,通過(guò)無(wú)性繁殖的蠕蟲(chóng)會(huì)因感染疾病而死亡,。印第安納大學(xué)的研究人員稱(chēng),,寄主和寄生蟲(chóng)都在努力盡快進(jìn)化,以便與對(duì)手齊頭并進(jìn),,在競(jìng)爭(zhēng)中不會(huì)輸給對(duì)方,。他們認(rèn)為性行為對(duì)進(jìn)化確實(shí)沒(méi)有意義,因?yàn)檫@經(jīng)常需要涉及到雄性的成果,。這種方法的效率很低,,因?yàn)樾坌圆⒉荒苤苯由蟠?/p>
自體受精是更加有效的繁殖方式,據(jù)進(jìn)化理論預(yù)測(cè),,自體受精在自然界中應(yīng)該很普遍,,而兩性性行為應(yīng)該很少見(jiàn)。但是雙親的DNA結(jié)合在一起,,性行為令它們產(chǎn)生的后代具備雙親的不同優(yōu)點(diǎn),。通過(guò)自體受精繁殖的后代,僅繼承了單親的DNA,,任何能夠傳染給母體的寄生蟲(chóng)病,,也都能傳染它們的后代。這種進(jìn)化理論是由劉易斯·卡羅爾在《愛(ài)麗絲夢(mèng)游仙境》里提出的,,他寫(xiě)道:“你要盡可能地跑,,才能保證與對(duì)手并駕齊驅(qū)。”
這項(xiàng)研究的聯(lián)合論文作者柯蒂斯·李偉利說(shuō):“據(jù)紅皇后假說(shuō)(The Red Queen hypothesis)推測(cè),,性行為應(yīng)該有助于寄主避開(kāi)寄生蟲(chóng)感染,,而自體授精增加了被感染的風(fēng)險(xiǎn)。”這些研究人員著眼于兩群蠕蟲(chóng),,一群通過(guò)交配繁殖后代,,而另一群只能通過(guò)自體授精,。研究發(fā)現(xiàn),后者更容易被細(xì)菌感染和死亡,。他們對(duì)這些蠕蟲(chóng)繁殖的20代后代進(jìn)行了研究,。
李偉利說(shuō):“共同進(jìn)化的寄生蟲(chóng)似乎在自然界中很普遍。該試驗(yàn)顯示,,與寄生蟲(chóng)共同進(jìn)化,,但是寄生蟲(chóng)本身并未出現(xiàn),這需要更高水平的異型雜交,。寄主和寄生蟲(chóng)之間的共同進(jìn)化之戰(zhàn),,也許解釋了雄性存在的原因。”(生物谷Bioon.com)
生物谷推薦原文出處:
Science DOI: 10.1126/science.1206360
Running with the Red Queen: Host-Parasite Coevolution Selects for Biparental Sex
Morran, Levi T.; Schmidt, Olivia G.; Gelarden, Ian A.; Parrish, Raymond C.; Lively, Curtis M.
Most organisms reproduce through outcrossing, even though it comes with substantial costs. The Red Queen hypothesis proposesthat selection from coevolving pathogens facilitates the persistence of outcrossing despite these costs. We used experimentalcoevolution to test the Red Queen hypothesis and found that coevolution with a bacterial pathogen (Serratia marcescens) resulted in significantly more outcrossing in mixed mating experimental populations of the nematode Caenorhabditis elegans. Furthermore, we found that coevolution with the pathogen rapidly drove obligately selfing populations to extinction, whereasoutcrossing populations persisted through reciprocal coevolution. Thus, consistent with the Red Queen hypothesis, coevolvingpathogens can select for biparental sex.