Effects of fruit dimorphism on genetic structure and gene flow in the coastal shrub Scaevola taccada
Effects of fruit dimorphism on genetic structure and gene flow in the coastal shrub Scaevola taccada
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果实二态性对沿海灌木 Scaevola taccada 遗传结构和基因流的影响
DOI：
10.1093/aob/mcac138
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发表时间：
2022
期刊：
影响因子：
4.2
通讯作者：
Hiroshi Kudoh
中科院分区：
文献类型：
--
作者：
Naoko Emura;Tomoaki Muranaka;Takaya Iwasaki;Mie N Honjo;Atsushi J Nagano;Yuji Isagi;Hiroshi Kudoh
背景和目的植物繁殖体通常具有特殊的形态，有利于在特定的景观中传播。在沿海灌木scevola taccada的果实二态性中，单个植株产生软木状或浆状果实。前者是浮力的，在沙滩上很常见，而后者不漂浮，鸟类分散，常见于高架地点，如海边悬崖的斜坡和岩石海岸后面。我们假设，海滩种群通过作为两种水果的来源，架起了异质景观的桥梁，而岛屿内高海拔地区的果肉形态和不同岛屿海滩之间的软木形态的分散是有偏见的。基于这一假设，我们预测，由于距离隔离，高海拔地区的种群将随着时间的推移而遗传分化，而海滩种群将通过当前的基因流保持高度的遗传相似性。方法遗传结构和基因流。通过调查来自日本6个岛屿（琉球、大东和小笠原群岛）17个采样点的植物全基因组单核苷酸多态性，对taccadaha进行了评估。主要结果：三个遥远岛屿群之间存在地理隔离。对琉球群岛的分析表明，沙滩种群具有遗传混合的特征，而高海拔地区的种群在岛屿之间相对孤立。海岛间的efst2值在沙滩之间最低，沙滩与高架场地之间居中，高架场地之间最高。结论在不同岛屿的海滩上，软木变形在海洋上的传播足够频繁，从而防止了遗传分化。岛屿间较高位置的较强遗传隔离表明，鸟类通过浆状形态的传播主要局限于岛屿内。这些由果实二态性实现的基因流动的对比模式提供了证据，证明果实特征可以强烈地调节遗传结构。
Background and AimsPlant propagules often possess specialized morphologies that facilitate dispersal across specific landscapes. In the fruit dimorphism of a coastal shrub,Scaevola taccada, individual plants produce either cork-morph or pulp-morph fruits. The former is buoyant and common on sandy beaches, whereas the latter does not float, is bird-dispersed, and is common on elevated sites such as slopes on sea cliffs and behind rocky shores. We hypothesized that beach populations bridge the heterogeneous landscapes by serving as a source of both fruit types, while dispersal is biased for the pulp morph on elevated sites within the islands and for the cork morph between beaches of different islands. Based on this hypothesis, we predicted that populations in elevated sites would diverge genetically over time due to isolation by distance, whereas beach populations would maintain high genetic similarity via current gene flow.MethodsThe genetic structure and gene flow inS. taccadawere evaluated by investigating genome-wide single nucleotide polymorphisms in plants from 17 sampling sites on six islands (belonging to the Ryukyu, Daito and Ogasawara Islands) in Japan.Key ResultsGeographical isolation was detected among the three distant island groups. Analyses within the Ryukyu Islands suggested that sandy beach populations were characterized by genetic admixture, whereas populations in elevated sites were relatively isolated between the islands. PairwiseFSTvalues between islands were lowest between sandy beaches, intermediate between sandy beaches and elevated sites, and highest between elevated sites.ConclusionsDispersal across the ocean by cork morphs is sufficiently frequent to prevent genetic divergence between beaches of different islands. Stronger genetic isolation of elevated sites between islands suggests that bird dispersal by pulp morphs is restricted mainly within islands. These contrasting patterns of gene flow realized by fruit dimorphism provide evidence that fruit characteristics can strongly mediate genetic structure.