Wright Alison E, Harrison Peter W, Zimmer Fabian, Montgomery Stephen H, Pointer Marie A, Mank Judith E
Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, OX1 3PS, UK; Department of Genetics, Evolution and Environment, University College London, London, WC1E 6BT, UK.
Mol Ecol. 2015 Mar;24(6):1218-35. doi: 10.1111/mec.13113.
Higher rates of coding sequence evolution have been observed on the Z chromosome relative to the autosomes across a wide range of species. However, despite a considerable body of theory, we lack empirical evidence explaining variation in the strength of the Faster-Z Effect. To assess the magnitude and drivers of Faster-Z Evolution, we assembled six de novo transcriptomes, spanning 90 million years of avian evolution. Our analysis combines expression, sequence and polymorphism data with measures of sperm competition and promiscuity. In doing so, we present the first empirical evidence demonstrating the positive relationship between Faster-Z Effect and measures of promiscuity, and therefore variance in male mating success. Our results from multiple lines of evidence indicate that selection is less effective on the Z chromosome, particularly in promiscuous species, and that Faster-Z Evolution in birds is due primarily to genetic drift. Our results reveal the power of mating system and sexual selection in shaping broad patterns in genome evolution.
在广泛的物种中，相对于常染色体，人们观察到Z染色体上编码序列的进化速率更高。然而，尽管有大量的理论，但我们缺乏实证证据来解释“更快的Z效应”强度的变化。为了评估“更快的Z进化”的程度和驱动因素，我们组装了六个从头转录组，涵盖了9000万年的鸟类进化历程。我们的分析将表达、序列和多态性数据与精子竞争和滥交的测量结果相结合。通过这样做，我们提供了首个实证证据，证明了“更快的Z效应”与滥交测量结果之间的正相关关系，进而证明了雄性交配成功率的差异。我们从多方面证据得出的结果表明，选择在Z染色体上的效果较差，尤其是在滥交物种中，鸟类的“更快的Z进化”主要是由于遗传漂变。我们的结果揭示了交配系统和性选择在塑造基因组进化广泛模式方面的作用。
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