Ontogenetic Complexity of Sexual Dimorphism and Sex-Specific Selection
Ontogenetic Complexity of Sexual Dimorphism and Sex-Specific Selection
复制标题
DOI：
10.1093/molbev/msq042
复制
发表时间：
2010-07-01
影响因子：
10.7
通讯作者：
Ellegren, Hans
中科院分区：
文献类型：
--
作者：
Mank, Judith E.;Nam, Kiwoong;Ellegren, Hans
性别偏倚基因表达正成为分子遗传水平上研究性选择的重要途径。然而，人们对产生不同的雄性和雌性表型所需的基因表达的时间、持久性和连续性知之甚少，对性别特异性选择压力如何在生命周期中转移的了解就更少了。在这里，我们展示了雄性和雌性鸡常染色体基因的时间序列全球转录谱，从胚胎发育开始，跨越到性腺的生殖成熟。总的来说，性别偏倚表达的数量和幅度随着年龄的增长而增加，尽管性别偏倚基因的表达令人惊讶地短暂，很少有基因在胚胎和成年组织中都表现出持续的性别偏倚。尽管性染色体在两性二态性中有很大的预测作用，但我们的研究表明，常染色体容纳了大多数具有性别偏倚表达的基因。最有趣的是，性别特异性的进化压力在生命周期的过程中发生了变化，对偏向女性的基因和偏向男性的基因的作用同样强烈，但在不同的年龄。在胚胎发育后期，在减数分裂停止卵发生前不久，偏向雌性的基因表现出很高的分化率。雌性偏向晚期胚胎基因的差异水平与成年性腺中表达的雄性偏向基因相似，这与精子发生的开始有关。这些分析表明，性别特异性的选择压力在整个生命周期中作为雄性和雌性生物学的功能而变化。
Sex-biased gene expression is becoming an increasingly important way to study sexual selection at the molecular genetic level. However, little is known about the timing, persistence, and continuity of gene expression required in the creation of distinct male and female phenotypes, and even less about how sex-specific selection pressures shift over the life cycle. Here, we present a time-series global transcription profile for autosomal genes in male and female chicken, beginning with embryonic development and spanning to reproductive maturity, for the gonad. Overall, the amount and magnitude of sex-biased expression increased as a function of age, though sex-biased gene expression was surprisingly ephemeral, with very few genes exhibiting continuous sex bias in both embryonic and adult tissues. Despite a large predicted role of the sex chromosomes in sexual dimorphism, our study indicates that the autosomes house the majority of genes with sex-biased expression. Most interestingly, sex-specific evolutionary pressures shifted over the course of the life cycle, acting equally strongly on female-biased genes and male-biased genes but at different ages. Female-biased genes exhibited high rates of divergence late in embryonic development, shortly before arrested meiosis halts oogenesis. The level of divergence on female-biased late embryonic genes is similar to that seen in male-biased genes expressed in adult gonads, which correlates with the onset of spermatogenesis. These analyses reveal that sex-specific selection pressure varies over the life cycle as a function of male and female biology.