Mating systems of diploid and allotetraploid populations of Tragopogon (Asteraceae).: I.: Natural populations
Mating systems of diploid and allotetraploid populations of Tragopogon (Asteraceae).: I.: Natural populations
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DOI：
10.1038/sj.hdy.6884620
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发表时间：
1999-03-01
期刊：
影响因子：
3.8
通讯作者：
Soltis, PS
中科院分区：
文献类型：
--
作者：
Cook, LM;Soltis, PS
虽然多倍性是植物多样化的重要力量，但多倍化的进化后果还没有完全了解。大多数群体遗传理论预测的多倍体的一个可能后果是，新合成的多倍体将以比其二倍体祖先更高的速率自花受精。为了研究提高多倍体自交率的方法，对异源四倍体大柳参及其二倍体祖先之一大柳参的交配系统进行了研究。，进行比较。Tragopogon mirus是最近衍生的物种，在过去80年的某个时候出现，因此提供了一个机会来探索异交率的变化可能会有多快。通过对母本植株和后代群体的变异分析，发现两个四倍体群体的异交率均高于两个二倍体群体。这一结果与群体遗传理论的预测相反。理论和经验结果之间的这种差异可能是由于遗传样本中的偏差，所涉及的分类群的自然历史中的性状，或者自多倍体形成以来缺乏足够的时间（80年或40-80代）来增加自交的转变。或者，通常应用于多倍体的近交衰退的部分显性模型可能不合适;超显性模型预测二倍体及其四倍体衍生物的异交率与T.和T. mirus。
Although polyploidy is a significant force in the diversification of plants, the evolutionary consequences of polyploidization are not thoroughly understood. One possible consequence of polyploidy predicted by most population genetic theories is that the newly synthesized polyploid will self-fertilize at a greater rate than its diploid progenitors. To test for increased selfing rates in a polyploid, the mating systems of the allotetraploid Tragopogon mirus and one of its diploid progenitors, T. dubius, were compared. Tragopogon mirus is a recently derived species that arose sometime in the last 80 years and thus provides an opportunity to probe how quickly a shift in outcrossing rates might occur. Based on analyses of variation in maternal plants and their progeny arrays, the two tetraploid populations surveyed have higher outcrossing rates than the two diploid populations. This result is the opposite of that predicted by population genetic theory. This discrepancy between theoretical and empirical results may result from bias in the genetic sample, traits in the natural histories of the taxa involved or a lack of sufficient time since the formation of the polyploid (80 years or 40-80 generations) for a shift towards increased selfing to have occurred. Alternatively, the partial dominance model of inbreeding depression typically applied to polyploids may not be appropriate; the overdominance model predicts outcrossing rates in diploids and their tetraploid derivatives that are consistent with those observed in T. dubius and T. mirus.