Constraints on the evolution of chromosome dosage compensation: a test in butterflies and moths

这项研究解决了当个体具有不同数量的每个基因拷贝时基因如何进化的问题。在许多物种中，个体的性别取决于一个人拥有多少个决定性别的染色体拷贝。在人类中，女性有两个X染色体副本，男性只有一个。基因表达水平通常反映基因剂量：个体中存在多少基因拷贝。破坏染色体之间的基因剂量平衡通常会产生严重的负面后果。了解机制如何以及为什么进化以补偿不平衡的基因剂量是医学和进化研究的一个重要目标。这个项目的重点是蛾和蝴蝶，其中男性有两个副本的性别决定染色体和女性只有一个。该项目将系统地调查与蛾和蝴蝶性别决定染色体相关的剂量补偿。它还将测试突变率和自然选择等因素如何在决定平衡基因表达的进化中发挥作用。研究人员将利用飞蛾和蝴蝶的广泛公众吸引力作为增加公众参与和科学研究知识的手段。 理论预测，两性之间应该存在一种补偿X连锁基因表达的机制。对不同物种的观察表明，这些机制往往已经进化，但有时却没有。造成这种差异的原因尚不清楚。初步结果表明，飞蛾和蝴蝶在剂量补偿的幅度上存在有趣的变化。这项研究将结合联合收割机转录组和基因组测序来表征10种遗传多样的蛾或蝴蝶物种的剂量补偿模式。 RNA测序将提供基因表达的全基因组估计，以测试性别之间在性连锁基因表达方面的差异。这种广泛的调查剂量补偿将解决有关性别决定染色体剂量补偿存在的问题，在这个突出的女性heterogametic taxon.Comparative基因组分析和重测序的目标物种将被用来推断男性突变的偏见和相对有效的人口规模的性别决定染色体和其他染色体的模式。预计这些群体遗传因素与剂量补偿的存在相关，并将在不同种属之间进行比较，以检验这种关系。

This research addresses the question of how genes evolve when individuals have different numbers of copies of each gene. In many species, the sex of the individual is determined by how many copies of the sex-determining chromosomes one has. In humans, females have two copies of the X chromosome and males have just one. Levels of gene expression usually reflect gene dosage: how many gene copies are present in an individual. Disrupting the balance of gene dosage between chromosomes typically has severe negative consequences. Understanding how and why mechanisms evolve to compensate for unbalanced gene dosage is an important goal both for medical and evolutionary research. This project focuses on moths and butterflies in which males have two copies of the sex-determining chromosome and females have just one. This project will systematically survey dosage compensation associated with sex-determining chromosomes in moths and butterflies. It will also test how factors like mutation rates and natural selection play a role in determining the evolution of balanced gene expression. The researchers will use the wide public appeal of moths and butterflies as a means to increase public engagement and knowledge about scientific research. Theory predicts that a mechanism should exist for compensating X-linked gene expression between the sexes. Observations from different species reveal that often such mechanisms have evolved, but sometimes they do not. The reasons for this difference are not understood. Preliminary results suggest moths and butterflies harbor intriguing variation in the magnitude of dosage compensation. The research will combine transcriptome and genome sequencing to characterize patterns of dosage compensation in 10 phylogenetically diverse moth or butterfly species. RNA-sequencing will provide genome-wide estimates of gene expression to test for differences between sexes in sex-linked gene expression. This broad survey of dosage compensation will resolve questions regarding the presence of sex-determining chromosome dosage compensation in this prominent female-heterogametic taxon. Comparative genomic analyses and resequencing of targeted species will be used to infer patterns of male mutation bias and the relative effective population sizes of sex-determining chromosomes and other chromosomes. These population genetic factors are expected to correlate with the presence of dosage compensation and will be compared across species to test for such a relationship.