Am Nat. 2021 Mar;197(3):E72-E88. doi: 10.1086/712603. Epub 2021 Jan 29.
AbstractCompared to those of their parents, are the traits of first-generation (F) hybrids typically intermediate, biased toward one parent, or mismatched for alternative parental phenotypes? To address this empirical gap, we compiled data from 233 crosses in which traits were measured in a common environment for two parent taxa and their F hybrids. We find that individual traits in Fs are halfway between the parental midpoint and one parental value. Considering pairs of traits together, a hybrid's bivariate phenotype tends to resemble one parent (parent bias) about 50% more than the other, while also exhibiting a similar magnitude of mismatch due to different traits having dominance in conflicting directions. Using data from an experimental field planting of recombinant hybrid sunflowers, we illustrate that parent bias improves fitness, whereas mismatch reduces fitness. Our study has three major conclusions. First, hybrids are not phenotypically intermediate but rather exhibit substantial mismatch. Second, dominance is likely determined by the idiosyncratic evolutionary trajectories of individual traits and populations. Finally, selection against hybrids likely results from selection against both intermediate and mismatched phenotypes.
摘要与父母相比，第一代（F）杂种的特征通常是中间型、偏向一方亲本，还是与另一方亲本表型不匹配？为了解决这一经验上的差距，我们编译了来自 233 个杂交实验的数据，这些实验在共同环境中测量了两个亲代分类群及其 F 杂种的特征。我们发现 F 代个体特征在双亲的中点和一个亲本值之间的中间位置。考虑到两对特征，杂种的双变量表型更倾向于类似于一个亲本（亲本偏向）约 50%，而由于不同特征具有相互矛盾的优势方向，也表现出相似程度的不匹配。我们使用来自重组杂交向日葵田间种植的实验数据来说明，亲本偏向提高了适应性，而不匹配降低了适应性。我们的研究有三个主要结论。首先，杂种不是表型中间型，而是表现出明显的不匹配。其次，显性可能是由个体特征和种群的特殊进化轨迹决定的。最后，对杂种的选择可能是由于对中间型和不匹配表型的选择造成的。
