Relatively weak inbreeding depression in selfing but also in outcrossing populations of North American Arabidopsis lyrata
Relatively weak inbreeding depression in selfing but also in outcrossing populations of North American Arabidopsis lyrata
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DOI：
10.1111/jeb.13169
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发表时间：
2017-11-01
影响因子：
2.1
通讯作者：
Stift, M.
中科院分区：
文献类型：
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作者：
Carleial, S.;van Kleunen, M.;Stift, M.
雌雄同体的植物可能会自花受精，但大多数具有促进异交的适应能力。然而，向更高的自交率的进化过渡是频繁的。与异交相比，自交具有传递优势，但自交后代可能会遭受近交衰退，这构成了更高自交率进化的主要障碍。在这里，我们评估了近亲繁殖抑郁症在北美的草药拟南芥，这是正常的自交不亲和，自交不亲和的植物频率低。然而，少数群体已成为固定的自交亲和性，并有很高的自交率。在温室条件下，我们估计平均每粒种子的近交衰退（基于累积的营养性能计算为产品的发芽，存活和地上生物量）为0.34为6个异交群体，和0.26为5个自交群体。暴露于干旱和诱导防御与茉莉酸没有放大这些估计。然而，对于异交种群，每粒种子的近交衰退可能低估了近交衰退的真实水平，因为自交不亲和的植物在（强制）自交后结实率明显降低。近交衰退的估计，将种子集平均为0.63异交群体（相比，0.30自交群体）。然而，这可能是高估，因为将植物暴露于5%CO2以规避自交不亲和性以产生自交种子可能会留下自交不亲和性的残余影响，从而导致结实率降低。然而，我们的估计近交衰退明显低于以前的估计，基于相同的性能性状在异交欧洲人口的A.lyrata，这可能有助于解释为什么自交可以在北美A. lyrata的发展。
Hermaphroditic plants can potentially self-fertilize, but most possess adaptations that promote outcrossing. However, evolutionary transitions to higher selfing rates are frequent. Selfing comes with a transmission advantage over outcrossing, but self-progeny may suffer from inbreeding depression, which forms the main barrier to the evolution of higher selfing rates. Here, we assessed inbreeding depression in the North American herb Arabidopsis lyrata, which is normally self-incompatible, with a low frequency of self-compatible plants. However, a few populations have become fixed for self-compatibility and have high selfing rates. Under greenhouse conditions, we estimated mean inbreeding depression per seed (based on cumulative vegetative performance calculated as the product of germination, survival and aboveground biomass) to be 0.34 for six outcrossing populations, and 0.26 for five selfing populations. Exposing plants to drought and inducing defences with jasmonic acid did not magnify these estimates. For outcrossing populations, however, inbreeding depression per seed may underestimate true levels of inbreeding depression, because self-incompatible plants showed strong reductions in seed set after (enforced) selfing. Inbreeding-depression estimates incorporating seed set averaged 0.63 for outcrossing populations (compared to 0.30 for selfing populations). However, this is likely an overestimate because exposing plants to 5% CO2 to circumvent self-incompatibility to produce selfed seed might leave residual effects of self-incompatibility that contribute to reduced seed set. Nevertheless, our estimates of inbreeding depression were clearly lower than previous estimates based on the same performance traits in outcrossing European populations of A.lyrata, which may help explain why selfing could evolve in North American A.lyrata.