Rethinking evolution in self-fertilising species

从基因组序列数据中确定自然选择的普遍性（包括有害和有利变异的存在）是进化遗传学的主要挑战。自然界中有相当数量的物种是雌雄同体，能够自我受精，个体产生可用于繁殖的雌性和雄性配子。来自这些物种的新出现的基因组数据产生了不寻常的选择特征，这些特征无法用传统的预测来解释，传统的预测假设选择作用于局部遗传区域。在自交受精的物种中，遗传变异是作为大的连锁区域遗传的，这可能会减少多样性，并导致连锁选择在更长的遗传距离上起作用。然而，也存在断断续续的多样性区域。SelectSelf将开发理论和基因组推断方法，以确定不同的选择力如何与这种生殖模式相互作用。工作计划1将开发模型和方法，以确定自交受精物种中间断多样性（平衡选择、渗入、暴露有害突变或残余异交）的原因。工作计划2将研究多基因性状的适应在多大程度上导致远程选择性扫描，并量化多效性对这一过程的影响。工作计划3将量化有害突变的分布如何受到这两种进化机制的连锁选择的影响。总之，新的方法和理论将应用于杆状线虫物种的数据，以推断自交受精线虫的超多样性和连锁选择的进化影响。该项目将为自然选择和繁殖如何相互作用以确定物种如何在自然环境中持续存在的知识提供一个步骤变化，从而产生分析和解释自交受精物种遗传数据的新标准。

Determining the prevalence of natural selection (including the presence of deleterious and favourable variants) from genome sequence data is a major challenge in evolutionary genetics. A sizeable number of species in nature are hermaphrodites capable of self-fertilisation, where individuals produce both female and male gametes that can be used to reproduce. Emerging genome data from such species has yielded unusual selection signatures that cannot be explained by classic predictions, which assume selection acts on local genetic regions. Genetic variation is inherited as large linked regions in self-fertilising species, which can decrease diversity and cause linked selection to act over longer genetic distances. Yet punctuated regions of diversity also exist. SelectSelf will develop theoretical and genome-inference methods to determine how different selective forces interact with this reproductive mode. Work plan 1 will develop models and methods to establish the causes of punctuated diversity (balancing selection, introgression, exposure of deleterious mutations, or residual outcrossing) in self-fertilising species. Work plan 2 will investigate to what extent adaptation by a polygenic trait will lead to long-range selective sweeps and quantify the effect of pleiotropy on this process. Work plan 3 will quantify how the distribution of deleterious mutations are affected by linked selection due to either of these evolutionary mechanisms. Throughout, new methods and theory will be applied to data from Caenorhabditis species to infer the evolutionary impacts of hyperdiversity and linked selection in self-fertilising nematodes. This project will provide a step-change in knowledge of how natural selection and reproduction interact to determine how species persist in natural environments, resulting in new standards for analysing and interpreting genetic data from self-fertilising species.