一項研究發(fā)現(xiàn),，自然選擇可能限制雄性果蠅的性吸引力,。Emma Hine及其同事設(shè)計了一個果蠅種群,，此種群中的具有能力釋放雌性果蠅最喜愛的一組信息素的雄性果蠅過多。為了進行比較,，這組科研人員還建立了第二組果蠅,，這組果蠅中的占據(jù)支配地位的雄性含有較少的刺激性化學(xué)素。這組作者說,，第一個種群中的具有信息素吸引力的雄性數(shù)量盡管在初期多一些,，在經(jīng)過了7代的選擇性培育之后數(shù)量穩(wěn)定了下來。在之后的這個種群自然繁殖時期,，這組科研人員觀察到,，僅僅經(jīng)過了5代，人為化增強雄性吸引力的效應(yīng)就下降了一半,。在第二組中,，不出所料，雌性與性吸引力不強的雄性交配的頻率顯著小于與其它雄性交配的頻率,。這組作者說,，這些發(fā)現(xiàn)提示讓雄性果蠅具有性吸引力的性狀可能減少這種昆蟲的總體適應(yīng)度，并有效地將種群中具有吸引力的雄性的比例控制到一定程度,。（生物谷Bioon.com）
生物谷推薦原文出處：
PNAS doi: 10.1073/pnas.1011876108
Natural selection stops the evolution of male attractiveness
Emma Hine1, Katrina McGuigan, and Mark W. Blows
Abstract
Sexual selection in natural populations acts on highly heritable traits and tends to be relatively strong, implicating sexual selection as a causal agent in many phenotypic radiations. Sexual selection appears to be ineffectual in promoting phenotypic divergence among contemporary natural populations, however, and there is little evidence from artificial selection experiments that sexual fitness can evolve. Here, we demonstrate that a multivariate male trait preferred by Drosophila serrata females can respond to selection and results in the maintenance of male mating success. The response to selection was associated with a gene of major effect increasing in frequency from 12 to 35% in seven generations. No further response to selection, or increase in frequency of the major gene, was observed between generations 7 and 11, indicating an evolutionary limit had been reached. Genetic analyses excluded both depletion of genetic variation and overdominance as causes of the evolutionary limit. Relaxing artificial selection resulted in the loss of 52% of the selection response after a further five generations, demonstrating that the response under artificial sexual selection was opposed by antagonistic natural selection. We conclude that male D. serrata sexually selected traits, and attractiveness to D. serrata females conferred by these traits, were held at an evolutionary limit by the lack of genetic variation that would allow an increase in sexual fitness while simultaneously maintaining nonsexual fitness. Our results suggest that sexual selection is unlikely to cause divergence among natural populations without a concomitant change in natural selection, a conclusion consistent with observational evidence from natural populations.
