Hybrid zones and the genetic architecture of a barrier to gene flow between two sunflower species.
Hybrid zones and the genetic architecture of a barrier to gene flow between two sunflower species.
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发表时间：
1999-06
期刊：
影响因子：
3.3
通讯作者：
L. Rieseberg;J. Whitton;Keith A. Gardner
中科院分区：
文献类型：
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作者：
L. Rieseberg;J. Whitton;Keith A. Gardner
生殖障碍的遗传分析是检验物种形成理论的少数方法之一。然而，遗传学研究往往局限于具有短世代时间和易于在实验室中繁殖的模式生物。具有不同年龄的重组基因型多样性的复制杂交区为遗传作图实验提供了更高的分辨率，并扩大了适于遗传研究的生物体库。利用分布在17条染色体上的88个标记，分析了向日葵染色体片段在H.一年生植物在三个自然杂交区。相对于26个染色体片段的中性预期，渐渗显著减少，表明每个片段包含一个或多个有助于隔离的因素。花粉不育与这26个片段中的16个显著相关，这提供了一个简单的解释，为什么这个子集的块是不利的杂种。此外，跨共线染色体与重排染色体的渐渗速率的比较表明，接近50%的渐渗障碍是由于染色体重排。这些结果表明，混合区的实用性，以确定因素，有助于隔离和验证的预测增加分辨率相对于控制交叉。
Genetic analyses of reproductive barriers represent one of the few methods by which theories of speciation can be tested. However, genetic study is often restricted to model organisms that have short generation times and are easily propagated in the laboratory. Replicate hybrid zones with a diversity of recombinant genotypes of varying age offer increased resolution for genetic mapping experiments and expand the pool of organisms amenable to genetic study. Using 88 markers distributed across 17 chromosomes, we analyze the introgression of chromosomal segments of Helianthus petiolaris into H. annuus in three natural hybrid zones. Introgression was significantly reduced relative to neutral expectations for 26 chromosomal segments, suggesting that each segment contains one or more factors that contribute to isolation. Pollen sterility is significantly associated with 16 of these 26 segments, providing a straightforward explanation of why this subset of blocks is disadvantageous in hybrids. In addition, comparison of rates of introgression across colinear vs. rearranged chromosomes indicates that close to 50% of the barrier to introgression is due to chromosomal rearrangements. These results demonstrate the utility of hybrid zones for identifying factors contributing to isolation and verify the prediction of increased resolution relative to controlled crosses.