Bersabé Diego, Caballero Armando, Pérez-Figueroa Andrés, García-Dorado Aurora
Departamento de Genética, Facultad de Biología, Universidad Complutense, 28040 Madrid, Spain.
Departamento de Bioquímica, Genética e Inmunología, Facultad de Biología, Universidad de Vigo, 36310 Vigo (Pontevedra), Spain.
G3 (Bethesda). 2015 Nov 12;6(1):171-81. doi: 10.1534/g3.115.023184.
Using computer simulation we explore the consequences of linkage on the inbreeding load of an equilibrium population, and on the efficiency of purging and the loss of genetic diversity after a reduction in population size. We find that linkage tends to cause increased inbreeding load due to the build up of coupling groups of (partially) recessive deleterious alleles. It also induces associative overdominance at neutral sites but rarely causes increased neutral genetic diversity in equilibrium populations. After a reduction in population size, linkage can cause some delay both for the expression of the inbreeding load and the corresponding purging. However, reasonable predictions can be obtained for the evolution of fitness under inbreeding and purging by using empirical estimates of the inbreeding depression rate. Purging selection against homozygotes for deleterious alleles affects the population's pedigree. Furthermore, it can slow the loss of genetic diversity compared to that expected from the variance of gametic contributions to the breeding group and even from pedigree inbreeding. Under some conditions, this can lead to a smaller loss of genetic diversity, even below that expected from population size in the absence of selection.
我们利用计算机模拟来探究连锁对平衡群体近亲繁殖负荷的影响，以及群体规模减小后清除作用的效率和遗传多样性的丧失情况。我们发现，由于（部分）隐性有害等位基因的耦合组积累，连锁往往会导致近亲繁殖负荷增加。它还会在中性位点诱导关联超显性，但在平衡群体中很少会导致中性遗传多样性增加。群体规模减小后，连锁可能会使近亲繁殖负荷的表达和相应的清除作用都出现一些延迟。然而，通过使用近亲繁殖衰退率的经验估计值，可以对近亲繁殖和清除作用下的适合度进化做出合理预测。针对有害等位基因纯合子的清除选择会影响群体的谱系。此外，与配子对繁殖群体贡献的方差甚至谱系近亲繁殖所预期的情况相比，它可以减缓遗传多样性的丧失。在某些条件下，这可能导致遗传多样性的丧失更小，甚至低于在没有选择的情况下群体规模所预期的水平。
