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首页> 外文期刊>Evolution: International Journal of Organic Evolution >Outbreeding depression varies among cohorts of Ipomopsis aggregata planted in nature
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Outbreeding depression varies among cohorts of Ipomopsis aggregata planted in nature

机译：在自然界中种植的怡宝（Ipomopsis aaggregata）队列中，远亲抑郁症有所不同

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Outbreeding depression in progeny fitness may arise from disruption of local adaptation, disruption of allelic coadaptation, or a combination of these "environmental" and ''physiological'' mechanisms. Thus the minimum spatial scale over which outbreeding depression arises should depend on the spatial scale of gene dispersal and (with an environmental mechanism) of change in selection regimes. We previously reported substantial outbreeding depression in lifetime fitness of progeny resulting from crosses among parents separated by 100 m in natural populations of the herbaceous plant Ipomopsis aggregata. In this paper we explore the effect of crossing distance on fitness in two additional experiments begun in 1987 and 1990. We planted seed progeny derived from partial diallel crossing designs in randomized blocks in maternal environments and scored emergence of seedlings, survival, and eventual flowering of individuals over the subsequent six to eight years. Nested within each diallel design were crossing distances of 1 m, 10 m, and 100 m. Compared to 1-m and 10-m progeny, 100-m progeny of the 1987 diallel suffered a significant reduction in seedling emergence, and both 1-m and 100-m progeny that survived to flower achieved lower lambda-values on average than 10-m progeny. Total outbreeding depression suffered by 100-m relative to 10-m progeny was approximately 10%, compared to approximately 30% in our earlier study of I. aggregata. Progeny of 10-m crosses also outperformed 1-m and 100-m progeny of the 1990 diallel by approximately 5%, but no difference among crossing distance treatments was significant. Thus, the magnitude of outbreeding depression in 100-m crosses varied among experiments. This is not surprising given likely spatial and temporal variation in gene flow and selection regimes, different population histories, and different parental and progeny environments. Characterizing outbreeding depression on the shortest spatial scales over which it is expressed, as well as its variation and causes, is worthwhile because it promises to shed light on the earliest stages of angiosperm speciation. [References: 63]
机译：后代适应性的近亲衰退可能源于局部适应的破坏，等位基因共适应的破坏或这些“环境”和“生理”机制的组合。因此，发生近亲衰退的最小空间尺度应取决于基因扩散的空间尺度和选择机制的变化（具有环境机制）。我们之前曾报道过，由于草本植物Ipomopsis aaggregata的自然种群中相距100 m的父母之间的杂交，导致子代一生的适应度大大降低。在本文中，我们在1987年和1990年开始的另外两个实验中，研究了杂交距离对适应性的影响。我们在母本环境中的随机区组中种植了部分偏二倍体杂交设计衍生的种子后代，并对种子的出苗，存活和最终开花进行了评分个人在随后的六到八年内。嵌套在每个Dialell设计中的交叉距离分别为1 m，10 m和100 m。与1m和10m后代相比，1987年拨号的100m后代幼苗出苗率显着降低，存活到花朵的1m和100m后代的平均λ值低于10。 -m后代。相对于10m后代而言，100m的总近亲繁殖抑郁大约为10％，而我们之前对I.aggregata的研究大约为30％。 10 m杂交的后代也比1990年的Dialall的1 m和100 m子代高出约5％，但是杂交距离之间的差异无显着性。因此，各实验中100 m杂交的近交衰退程度不同。考虑到基因流和选择机制，不同的种群历史以及不同的亲本和后代环境可能发生时空变化，这不足为奇。在最短的空间尺度上表征近亲衰退及其变化和原因是值得的，因为它有望揭示被子植物物种形成的最早阶段。 [参考：63]

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