Severe inbreeding depression is predicted by the "rare allele load" in Mimulus guttatus
Severe inbreeding depression is predicted by the "rare allele load" in Mimulus guttatus
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DOI：
10.1111/evo.13876
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发表时间：
2019-11-28
期刊：
影响因子：
3.3
通讯作者：
Kelly, John K.
中科院分区：
文献类型：
--
作者：
Brown, Keely E.;Kelly, John K.
大多数开花植物是雌雄同体的，并经历强大的压力来进化自花授粉（自动选择和生殖保证）。近交衰退（ID）可以反对选择自交，但目前还不清楚，如果ID是典型的强大到足以维持异交。为了测量持续近亲繁殖的健身的全部成本，其基因组基础上，我们种植高度纯合，完全基因组测序的黄monkeyflower（Mimulus guttatus）的近交系在该领域旁边的远交植物从相同的线之间的杂交。完全纯合的代价是严重的：65%的生存和86%的终身种子生产。考虑到致死和不育突变的不可测量的影响，我们估计完全近交基因型的平均适合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超显性的迹象，但一个线携带的稀有等位基因的数量，特别是在稀有等位基因簇非随机分布在整个基因组，是一个显着的负面预测健身测量。这些研究结果是一致的ID的有害等位基因模型。稀有等位基因负载线之间的高方差和稀有等位基因的基因组分布都表明，移民可能是一个重要的来源，有害等位基因的当地人口。
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.