PDF(Pubmed)
Abstract：
Inbreeding is unavoidable in small populations. However, the deleterious effects of inbreeding on fitness-related traits (inbreeding depression) may not be an inevitable phenomenon, since deleterious recessive alleles causing inbreeding depression might be purged from populations through inbreeding and selection. Inbreeding purging has been of great interest in conservation biology and animal breeding, because populations manifesting lower inbreeding depression could be created even with a small number of breeding animals, if inbreeding purging exists. To date, many studies intending to detect inbreeding purging in captive and domesticated animal populations have been carried out using pedigree analysis. Ballou\'s ancestral inbreeding coefficient (FBAL-ANC) is one of the most widely used measurements to detect inbreeding purging, but the theoretical basis for FBAL-ANC has not been fully established. In most of the published works, estimates from stochastic simulation (gene-dropping simulation) have been used. In this report, the author provides a mathematical basis for FBAL-ANC and proposes a new estimate by hybridizing stochastic and deterministic computation processes. A stochastic simulation suggests that the proposed method could considerably reduce the variance of estimates, compared to ordinary gene-dropping simulation, in which whole gene transmissions in a pedigree are stochastically determined. The favorable property of the proposed method results from the bypass of a part of the stochastic process in the ordinary gene-dropping simulation. Using the proposed method, the reliability of the estimates of FBAL-ANC could be remarkably enhanced. The relationship between FBAL-ANC and other pedigree-based parameters is also discussed.
摘要：
近亲繁殖在小种群中是不可避免的。然而,近亲繁殖对适应性相关性状（近亲繁殖抑郁症）的有害影响可能不是不可避免的现象，由于导致近亲繁殖抑郁症的有害隐性等位基因可能会通过近亲繁殖和选择从种群中清除。近亲繁殖净化在保护生物学和动物育种中引起了极大的兴趣，因为即使有少量繁殖动物，也可以创造出表现出较低近亲繁殖抑郁的种群，如果存在近亲繁殖清洗。迄今为止,许多旨在检测圈养和驯养动物种群近亲繁殖净化的研究已经使用谱系分析进行了。Ballou的祖先近亲繁殖系数（FBAL-ANC）是检测近亲繁殖净化的最广泛使用的测量之一，但FBAL-ANC的理论基础尚未完全确立。在大多数出版的作品中，使用了随机模拟(基因丢弃模拟)的估计。在这份报告中,作者为FBAL-ANC提供了数学基础，并通过混合随机和确定性计算过程提出了一种新的估计。随机模拟表明，该方法可以大大减少估计的方差，与普通的基因删除模拟相比，其中家系中的整个基因传输是随机确定的。所提出的方法的有利性质是由于绕过了普通基因丢弃模拟中的一部分随机过程。使用所提出的方法，FBAL-ANC估计的可靠性可以显著提高。还讨论了FBAL-ANC与其他基于谱系的参数之间的关系。
