Intraspecific karyotypic polymorphism is highly concordant with allozyme variation in Lysimachia mauritiana (Primulaceae: Myrsinoideae) in Taiwan: implications for the colonization history and dispersal patterns of coastal plants.
Intraspecific karyotypic polymorphism is highly concordant with allozyme variation in Lysimachia mauritiana (Primulaceae: Myrsinoideae) in Taiwan: implications for the colonization history and dispersal patterns of coastal plants.
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DOI：
10.1093/aob/mcs192
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发表时间：
2012-11
期刊：
影响因子：
4.2
通讯作者：
Yoshiko Kono;Kuo-Fang Chung;Chih‐Hui Chen;Y. Hoshi;H. Setoguchi;C. Chou;K. Oginuma;C. Peng
中科院分区：
文献类型：
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作者：
Yoshiko Kono;Kuo-Fang Chung;Chih‐Hui Chen;Y. Hoshi;H. Setoguchi;C. Chou;K. Oginuma;C. Peng
背景和目的联合研究种内核型和遗传变异可以为历史、生态和细胞遗传学因素如何影响微进化提供独特的见解。毛里求斯（Lysimachia mauritiana）是一种沿海草本植物，表现出广泛的核型多态性，并在整个琉球群岛表现出复杂的细胞地理学模式。为了探索琉球群岛以南是否存在类似程度的染色体变异，并试图确定可能产生这些模式的机制，在台湾进行了全面采样。方法 对台湾本土及其邻近岛屿 42 个群体的 550 名个体进行有丝分裂中期核型分析。此外，还使用从 12 个地点采样的 314 名个体的 12 个同种酶（21 个位点）估计了遗传变异。主要结果 检测到四种染色体数目和八种细胞型，包括四种地方性细胞型。细胞型分布在地理上具有高度结构化，大多数人群中存在单一细胞型，四种主要细胞型主导台湾和澎湖群岛的北部、东部和南部。同种异型酶变异非常低，F统计表明群体分化水平极高，这意味着群体之间的基因流动有限。等位酶变异的聚类分析揭示了四个地理群体，每个群体都与四种主要细胞类型完美对应。细胞型分布和等位酶变异的地理结构可能是由遗传瓶颈引发的严重遗传漂移造成的，这表明台湾人群很可能源自四个独立的创始人事件。在少数具有多种细胞型的地区，细胞地理学模式和染色体进化的推论揭示了向北扩散的趋势，这与影响该地区沿海生物群形成的黑潮流向一致。结论 这些数据阐明了台湾 L. mauritiana 的定殖模式和黑潮对 L. mauritiana 分布的影响。这些推论与该地区其他沿海植物物种高度相关，并将刺激进一步的研究。
BACKGROUND AND AIMS Investigating intraspecific karyotypic and genetic variations jointly can provide unique insights into how historical, ecological and cytogenetic factors influence microevolution. A coastal herb, Lysimachia mauritiana, exhibits extensive karyotypic polymorphism and displays a complex cytogeographic pattern across the Ryukyus. To explore whether a similar degree of chromosomal variation exists south of the Ryukyus, and in an attempt to ascertain the mechanisms that may have generated the patterns, comprehensive sampling was conducted in Taiwan. METHODS Karyotypes were analysed at mitotic metaphase for 550 individuals from 42 populations throughout Taiwan Proper and its adjacent islands. In addition, genetic variation was estimated using 12 allozymes (21 loci) of 314 individuals sampled from 12 localities. KEY RESULTS Four chromosome numbers and eight cytotypes, including four endemic cytotypes, were detected. Cytotype distributions were highly structured geographically, with single cytotypes present in most populations and four major cytotypes dominating the north, east and south of Taiwan and the Penghu Archipelago. Allozyme variation was very low and F-statistics indicated an extremely high level of population differentiation, implying limited gene flow among populations. Cluster analysis of allozyme variation uncovered four geographic groups, each corresponding perfectly to the four dominant cytotypes. The geographic structure of cytotype distribution and allozyme variation probably resulted from severe genetic drift triggered by genetic bottlenecks, suggesting that Taiwanese populations were likely to be derived from four independent founder events. In the few localities with multiple cytotypes, cytogeographic patterns and inferences of chromosomal evolution revealed a trend of northward dispersal, consistent with the course of the Kuroshio Current that has been influential in shaping the coastal biota of the region. CONCLUSIONS The data elucidate the patterns of colonization and the effects of the Kuroshio Current on the distribution of L. mauritiana in Taiwan. These inferences are highly relevant to other coastal plant species in the region and will stimulate further studies.