俗話說人不可貌相,，但有種魚卻喜歡根據(jù)外表顏色來選擇配偶,。研究顯示,，一個顏色基因的改變足以使一條這種魚變成“大眾情人”或飽受冷遇,，這一發(fā)現(xiàn)在生物學(xué)上具有重要意義,。
英國《BMC生物學(xué)》雜志29日刊登報告說,，日本研究人員對一種鳉魚進(jìn)行了實驗,。這種魚有多種顏色，其中棕色居多,，還有少量的橙色和灰色,。觀察顯示，顏色的不同決定了它們擇偶時的不同境遇,，橙色魚較受歡迎,，而灰色魚往往只能找顏色相同的同伴。
研究人員發(fā)現(xiàn)，這兩種截然不同的境遇實際上只由一個基因決定,。這個基因控制著橙色素的數(shù)量,，如果發(fā)生變異，這種魚可能會變成飽受冷落的灰色,。但如果通過人工手段使這個基因過度發(fā)揮作用,，可培育出具有“超級吸引力”的橙色魚，它色彩艷麗,，廣受追捧,。這些超級橙色魚在擇偶時也往往互相選擇，而對其他魚視而不見,。研究人員認(rèn)為,，如果這種基因變異長期傳承下去，將可能導(dǎo)致新物種的形成,。
研究人員說,，這是第一次發(fā)現(xiàn)單個基因可以同時改變生物的第二性征和擇偶偏好。過去人們認(rèn)為生物進(jìn)化由多個基因相互影響決定,，但這一研究表明,，也可能存在只有一個基因發(fā)生變異，逐漸形成不同物種的情況,。（生物谷bioon.com）
生物谷推薦原始出處：
BMC Biology 2009, 7:64doi:10.1186/1741-7007-7-64
Dual control by a single gene of secondary sexual characters and mating preferences in medaka
Shoji Fukamachi , Masato Kinoshita , Kouichi Aizawa , Shoji Oda , Axel Meyer and Hiroshi Mitani
Background
Animals utilize a wide variety of tactics to attract reproductive partners. Behavioral experiments often indicate an important role for visual cues in fish, but their molecular basis remains almost entirely unknown. Studies on model species (such as zebrafish and medaka) allow investigations into this fundamental question in behavioral and evolutionary biology.
Results
Through mate-choice experiences using several laboratory strains of various body colors, we successfully identified one medaka mutant (color interfere; ci) that is distinctly unattractive to reproductive partners. This unattractiveness seems to be due to reduced orange pigment cells (xanthophores) in the skin. The ci strain carries a mutation on the somatolactin alpha (SLa) gene, therefore we expected over-expression of SLa to make medaka hyper-attractive. Indeed, extremely strong mating preferences were detected in a choice between the ci and SLa-transgenic (Actb-SLa:GFP) medaka. Intriguingly, however, the strains showed opposite biases; that is, the mutant and transgenic medaka liked to mate with partners from their own strain, similar to becoming sexually isolated.
Conclusions
This study spotlighted SLa as a novel mate-choice gene in fish. In addition, these results are the first demonstration of a single gene that can pleiotropically and harmoniously change both secondary sexual characters and mating preferences. Although theoretical models have long suggested joint evolution of linked genes on a chromosome, a mutation on a gene-regulatory region (that is, switching on/off of a single gene) might be sufficient to trigger two 'runaway' processes in different directions to promote (sympatric) speciation.
