Maintenance of soil ecotypes of Solidago virgaurea in close parapatry via divergent flowering time and selection against immigrants
Maintenance of soil ecotypes of Solidago virgaurea in close parapatry via divergent flowering time and selection against immigrants
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通过不同的开花时间和针对移民的选择来维持近亲缘一枝黄花的土壤生态型
DOI：
10.1111/1365-2745.13034
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发表时间：
2018
影响因子：
5.5
通讯作者：
Ito Motomi
中科院分区：
文献类型：
--
作者：
Sakaguchi Shota;Horie Kenji;Ishikawa Naoko;Nishio Sae;Worth James R. P.;Fukushima Keitaro;Yamasaki Michimasa;Ito Motomi
蛇纹石地质的分布往往不均匀，可能会导致土壤和小气候的突然变化。因此，蛇形地区提供了一个理想的自然环境，以了解不同的选择如何驱动土壤特化植物的局部适应过程。当蛇纹石生态型被相关的非蛇纹石生态型包围时，自然选择和潜在基因流的平衡应该在很短的距离内维持不同的生态型。我们的目的是揭示日本一枝黄花植物的土壤生态型共存的机制。我们进行了实地调查来表征每个生态型的微环境和开花物候、共同花园和相互移植实验和人工杂交，以及种群遗传分析来研究生态型之间的遗传分化水平。生长室实验表明，与非蛇纹石植物相比，蛇纹石植物表现出较低的比叶面积 (SLA) 和更多的根系资源分配对应的，对蛇纹石栖息地干燥和贫瘠土壤条件的潜在适应。相互移植研究表明植物生长速率存在明显的局部适应模式。重要的是，蛇纹石种群在仲夏完成开花，而非蛇纹石植物则在夏末完成开花。这种模式与这样的假设是一致的：在开放栖息地的小气候条件变得严峻之前，早期开花可确保繁殖成功。尽管合子前隔离是基因流的强大障碍，但遗传分化非常低，表明蛇形生态型和/或低频基因流的最近起源。合成。研究结果表明，蛇纹石生态型的早期开花时间是由蛇纹石地区的小气候选择的，可以在当地适应中发挥作用，但也可以通过不同的繁殖时间的副产品来实现种群隔离。这项研究有助于对非常小的地理尺度下潜在基因流下植物生态物种形成的初始阶段的普遍了解。
The often patchy distribution of serpentine geology can lead to abrupt changes in soil and microclimates. Thus, serpentine areas provide an ideal natural setting to understand how divergent selection drives the process of local adaptation in edaphically specialized plants. When the serpentine ecotype is surrounded by a related nonserpentine ecotype, a balance of natural selection and potential gene flow should maintain the different ecotypes over very short distances. We aimed to reveal the mechanisms allowing soil ecotypes of a goldenrod species to co‐occur sympatrically in Japan.We performed field surveys to characterize microenvironments and flowering phenology of each ecotype, common garden and reciprocal transplant experiments and artificial crossing, and population genetic analysis to investigate the levels of genetic differentiation between ecotypes.Growth chamber experiments show that serpentine plants showed lower specific leaf area (SLA) and greater resource allocation to their root systems than did their nonserpentine counterparts, a potential adaptation to drier and less fertile soil condition in serpentine habitats. Reciprocal transplant studies demonstrated a clear pattern of local adaptation in the plant growth rate. Importantly, serpentine populations completed flowering by midsummer versus late summer in nonserpentine plants. This pattern is consistent with the hypothesis that early flowering ensures reproductive success, before the microclimatic conditions becomes severe in open habitats. Although prezygotic isolation was a strong barrier to gene flow, genetic differentiation was very low, indicating a recent origin for the serpentine ecotypes and/or gene flow at low frequencies.Synthesis. The findings indicate that the early flowering times of serpentine ecotypes, which would have been selected for by microclimates in serpentine areas, can play roles in local adaptation, but also population isolation via a by‐product of diverged reproductive timings. This study contributes to general understanding of the initial stages of plant ecological speciation under potential gene flow in very small geographic scales.