从同源片段到纯合子区域：一个包含选择的统一溯祖框架
From IBD tracts to runs of homozygosity: a unified coalescent framework including selection
AI总结：
研究将IBD片段和ROH的长度分布关系统一在溯祖框架中，推导相关概率密度函数，纳入多种参数，分析背景选择和选择性清除对其影响，提供计算工具，通过乳糖酶持久性实例说明理论应用。
摘要：
同源片段（IBD）和纯合子区域（ROH）分别代表染色体纯合性的理论和可观测方面。然而，它们长度分布之间的形式关系尚未确立。本文开发了一个溯祖框架，将这两个概念统一在一个单一的分析形式中，用于推断有效种群大小（Ne）和检测选择信号。推导了IBD片段长度的封闭形式概率密度函数，并通过明确模拟从真正重组断点到最近杂合侧翼标记位点的纯合性边界位移，将其扩展到可观测的ROH长度分布。纳入了突变、基因转换、有限标记密度和标记杂合性等参数来连接IBD片段和ROH。背景选择在表观片段长度上引入了系统的向上偏差，需要一个依赖世代的Ne，不能用单一恒定值捕获。选择性清除在中性焦点位点周围产生长度分布的不对称扭曲。这种不对称的符号表明所选位点所在焦点位点的一侧。这种方向信号是短暂的，清除后很快消散。相比之下，局部Ne减少给出的信号持续时间长得多，使这两个信号互补以确定清除的时间。提供了计算工具来预测背景选择和完全或部分选择性清除下的片段长度分布。通过检测和定位欧洲人群中与乳糖酶持久性相关的选择性清除来说明该理论的应用。
英文摘要：
Identity-by-descent (IBD) tracts and runs of homozygosity (ROH) represent the underlying and observable aspects of chromosomal autozygosity, but no formal relationship between them had been established. This study develops a coalescent framework that connects these concepts, providing tools for detecting selection signatures and extending the temporal range of effective population size (Ne) inference. Closed-form probability functions are derived for IBD tract lengths and mapped onto observable ROHs by modelling the displacement of autozygosity boundaries from true recombination breakpoints to the nearest heterozygous marker. This mapping explicitly accounts for mutation, gene conversion, marker density, and heterozygosity. Selection effects are incorporated analytically, yielding computational tools to predict tract length distributions under background selection and partial or complete selective sweeps. Background selection shifts IBD tract-length distributions toward longer tracts, an effect better explained by a generation-dependent Ne reduction below its neutral value than by a single constant Ne. Selective sweeps generate directional asymmetry in tract-length distributions at neutral sites linked with the selected locus, with its direction indicating on which side of the neutral site the selected locus resides. This asymmetry decays rapidly after the sweep, whereas the local Ne reduction estimated from the median tract length persists considerably longer. The coalescent framework is further extended to arbitrary time-varying population size, enabling insights into past demography across a wide temporal range.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
