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Severe inbreeding depression is predicted by the “rare allele load” in Mimulus guttatus
Evolution ( IF 3.3 ) Pub Date : 2019-11-28 , DOI: 10.1111/evo.13876 Keely E. Brown 1 , John K. Kelly 1
Evolution ( IF 3.3 ) Pub Date : 2019-11-28 , DOI: 10.1111/evo.13876 Keely E. Brown 1 , John K. Kelly 1
Affiliation
Most flowering plants are hermaphroditic and experience strong pressures to evolve self‐pollination (automatic selection and reproductive assurance). Inbreeding depression (ID) can oppose selection for selfing, but it remains unclear if ID is typically strong enough to maintain outcrossing. To measure the full cost of sustained inbreeding on fitness, and its genomic basis, we planted highly homozygous, fully genome‐sequenced inbred lines of yellow monkeyflower (Mimulus guttatus) in the field next to outbred plants from crosses between the same lines. The cost of full homozygosity is severe: 65% for survival and 86% for lifetime seed production. Accounting for the unmeasured effect of lethal and sterile mutations, we estimate that the average fitness of fully inbred genotypes is only 3–4% that of outbred competitors. The genome sequence data provide no indication of simple overdominance, but the number of rare alleles carried by a line, especially within rare allele clusters nonrandomly distributed across the genome, is a significant negative predictor of fitness measurements. These findings are consistent with a deleterious allele model for ID. High variance in rare allele load among lines and the genomic distribution of rare alleles both suggest that migration might be an important source of deleterious alleles to local populations.
中文翻译:
Mimulus guttatus 中的“稀有等位基因负荷”预测了严重的近交衰退
大多数开花植物是雌雄同体的,并且承受着进化自花授粉(自动选择和生殖保证)的强大压力。近交抑制 (ID) 可以反对自交选择,但目前尚不清楚 ID 通常是否足够强大以维持异交。为了衡量持续近交在适应性方面的全部成本及其基因组基础,我们在田间种植了高度纯合、全基因组测序的黄猴花(Mimulus guttatus)自交系,旁边是来自相同系之间杂交的远交植物。完全纯合的成本很高:65% 的存活率和 86% 的终生种子生产。考虑到致死和不育突变的无法测量的影响,我们估计完全近交基因型的平均适应度仅为远交竞争者的 3-4%。基因组序列数据没有提供简单的过度优势的迹象,但一个系携带的稀有等位基因的数量,尤其是在非随机分布在整个基因组的稀有等位基因簇中,是适应度测量的一个重要的负预测因子。这些发现与 ID 的有害等位基因模型一致。品系之间稀有等位基因负荷的高方差和稀有等位基因的基因组分布都表明,迁移可能是向当地种群有害等位基因的重要来源。
更新日期:2019-11-28
中文翻译:
Mimulus guttatus 中的“稀有等位基因负荷”预测了严重的近交衰退
大多数开花植物是雌雄同体的,并且承受着进化自花授粉(自动选择和生殖保证)的强大压力。近交抑制 (ID) 可以反对自交选择,但目前尚不清楚 ID 通常是否足够强大以维持异交。为了衡量持续近交在适应性方面的全部成本及其基因组基础,我们在田间种植了高度纯合、全基因组测序的黄猴花(Mimulus guttatus)自交系,旁边是来自相同系之间杂交的远交植物。完全纯合的成本很高:65% 的存活率和 86% 的终生种子生产。考虑到致死和不育突变的无法测量的影响,我们估计完全近交基因型的平均适应度仅为远交竞争者的 3-4%。基因组序列数据没有提供简单的过度优势的迹象,但一个系携带的稀有等位基因的数量,尤其是在非随机分布在整个基因组的稀有等位基因簇中,是适应度测量的一个重要的负预测因子。这些发现与 ID 的有害等位基因模型一致。品系之间稀有等位基因负荷的高方差和稀有等位基因的基因组分布都表明,迁移可能是向当地种群有害等位基因的重要来源。