通過對沒有視力的洞穴魚進行雜交實驗,，最近科學家成功地恢復了一些洞穴魚的視力,。
洞穴魚的形成大約在更新世中期，它們的祖先生活在地表,，而且是有視力的,。已有的研究表明，洞穴魚視力的退化至少經(jīng)歷了三次獨立的進化事件,。來自紐約大學的Richard Borowsky通過對生活在墨西哥東北部的不同的洞穴魚群體進行雜交實驗研究了洞穴魚的視力恢復情況,。結(jié)果表明，所有地表魚和洞穴魚雜交的子一代都具有完好的視力,。但是,，洞穴魚之間雜交的后代中子一代最多只有將近40%的個體視力完好，而子二代中視力完好的個體所占的比例則要低得多,。用來自不同地點的洞穴魚和地表魚的雜交后代作為親本雜交的后代中,，相距較遠的群體之間的后代其視力要遠高于由較近的群體間繁殖產(chǎn)生的后代。Richard Borowsky解釋說,，地理距離較近的群體間具有最近的共同祖先并且享有共同的眼睛位點,。洞穴魚的祖先處于地下沒有光的環(huán)境中已經(jīng)有100萬年的歷史了。因此,，主導進化方向的是環(huán)境因素,，而不是最初的基因類型。
相關論文發(fā)表在1月份的《當代生物學》（Current Biology）上,。（科學新聞雜志 王保成/編譯）
生物谷推薦原始出處：
（Current Biology）,，Vol 18, R23-R24，Richard Borowsky
Restoring sight in blind cavefish
Richard Borowsky
Summary
Twenty-nine populations of the blind cavefish, Astyanax mexicanus, are known from different caves in North-Eastern Mexico (Figure 1). They evolved from eyed, surface-dwelling forms which only reached the area in the mid-Pleistocene . Quantitative genetic analyses have shown that the evolutionary impairment of eye development — as well as the loss of pigmentation and other cave-related changes — results from mutations at multiple gene sites (‘eye loci’) . Eye loss has evolved independently at least three times and at least some of the eye loci involved differ between the different cave populations . Hybrids between blind cavefish from different caves have larger and better developed eye rudiments than their parents (Figure 2), reflecting these independent origins and complementation. Given the large number of mutations at different loci that have accumulated in these populations, we reasoned that hybridization among independently evolved populations might restore visual function. Here we demonstrate restoration of vision in cavefish whose immediate ancestors were blind and whose separate lineages may not have been exposed to light for the last one million years.
