PNAS：简单遗传方式使雄性进化更快
自从达尔文19世纪注意到雄孔雀比雌孔雀具有漂亮得多的尾羽之后，接连不断的观测表明，雄性的进化速度要比雌性快。这种现象一直以来令生物学家迷惑不解，既然两性本质上具有相同的基因，为什么会存在进化速度上的差异？美国科学家近日通过分析大量果蝇基因后认为，其中原因在于两性的遗传模式存在差别，雌性的遗传模式包括多种基因的交互作用，而雄性则要相对简单。这一发现有助于科学家深入研究疾病在男女两性身上不同的表现症状，以及对于治疗的不同反应。相关论文11月14日在线发表于美国《国家科学院院刊》（PNAS）上。
此次研究由美国佛罗里达大学遗传研究所的动物学副教授Marta Wayne领导完成。研究小组分析了雌雄两性果蝇共享的8607种基因，结果发现其中7617种在两性间存在表达差异。这意味着同一种基因在两性间发挥了不同的作用。
研究人员认为，两性性染色体的差异在其中发挥了重要的作用。雌性具有两条X染色体，相关基因之间会发生很多交互作用，显性基因会掩盖隐性基因的表达；而雄性只有一条X染色体，而且Y染色体上的基因很少，这使得基因间的交互作用不多，遗传方式更为直接。
研究人员相信，正是这一相对简单的遗传路径帮助雄性较好地应对了性别选择的压力，赢得雌性配偶并繁育数量众多的后代。
美国布朗大学的生物学教授David Rand认为，虽然之前也有过关于基因表达与遗传方式之间关系的研究，但是此次分析的数据量特别庞大，包括了果蝇基因组的大部分。他说：“此次研究显示了隐性和显性特征对于变异的重要性。雄性获得的好的特征会得到促进，坏的会遭到删除；而对于雌性来说，好坏特征可以并存，只不过有害特征没有表达而已。”（科学网 梅进/编译）
原始出处:
Published online before print November 14, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0705441104
Marta L. Wayne*,
,
, Marina Telonis-Scott*, Lisa M. Bono
, Larry Harshman¶, Artyom Kopp||, Sergey V. Nuzhdin**, and Lauren M. McIntyre,,
*Department of Zoology, University of Florida, Gainesville, FL 32611-8525; University of Florida Genetics Institute, University of Florida, Gainesville, FL 32610-3610; Department of Biological Sciences, Ohio University, Athens, OH 45701-2979; ¶Department of Biological Science, University of Nebraska, Lincoln, NE 68588; ||Department of Evolution and Ecology, University of California, Davis, CA 95616; **Department of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089; Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610-0266; and Department of Statistics, University of Florida, Gainesville, FL 32611-8545
Edited by Thomas W. Cline, University of California, Berkeley, CA, and approved September 25, 2007 (received for review June 11, 2007)
Abstract
Sexual selection drives faster evolution in males. The X chromosome is potentially an important target for sexual selection, because hemizygosity in males permits accumulation of alleles, causing tradeoffs in fitness between sexes. Hemizygosity of the X could cause fundamentally different modes of inheritance between the sexes, with more additive variation in males and more nonadditive variation in females. Indeed, we find that genetic variation for the transcriptome is primarily additive in males but nonadditive in females. As expected, these differences are more pronounced on the X chromosome than the autosomes, but autosomal loci are also affected, possibly because of X-linked transcription factors. These differences may be of evolutionary significance because additive variation responds quickly to selection, whereas nonadditive genetic variation does not. Thus, hemizygosity of the X may underlie much of the faster male evolution of the transcriptome and potentially other phenotypes. Consistent with this prediction, genes that are additive in males and nonadditive in females are overrepresented among genes responding to selection for increased mating speed.
microarray | sexual antagonism | sexual conflict | sexual selection | transcription
相关报道:
- 众说风云 (已有2条评论)
