Genetic Distinctiveness but Low Diversity Characterizes Rear-Edge Thuja standishii (Gordon) Carr. (Cupressaceae) Populations in Southwest Japan
Genetic Distinctiveness but Low Diversity Characterizes Rear-Edge Thuja standishii (Gordon) Carr. (Cupressaceae) Populations in Southwest Japan
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DOI：
10.3390/d13050185
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发表时间：
2021-04
期刊：
影响因子：
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通讯作者：
J. Worth;I. Tamaki;Ikutaro Tsuyama;P. Harrison;Kyoko Sugai;H. Sakio;M. Aizawa;S. Kikuchi
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文献类型：
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作者：
J. Worth;I. Tamaki;Ikutaro Tsuyama;P. Harrison;Kyoko Sugai;H. Sakio;M. Aizawa;S. Kikuchi
后缘种群具有重要的科学意义，因为它们可以包含核心范围种群中未发现的等位基因变异。然而，这些人群的遗传多样性和差异水平可能有所不同，反映出生活史特征、人口历史和人类影响的差异。利用 13 颗 EST 微卫星，我们研究了日本特有针叶树 Thuja Standishii (Gordon) Carr 后缘种群的遗传多样性和分化。从日本东北部的核心范围到日本西南部。全范围遗传分化中等（Fst = 0.087），东北种群分化较弱（Fst = 0.047），但具有较高的遗传多样性（平均种群水平Ar = 4.76和Ho = 0.59）。相比之下，后缘种群在遗传上存在分歧（Fst = 0.168），但包含很少的独特等位基因，遗传多样性较低（Ar = 3.73，Ho = 0.49）。超过核心范围内观察到的水平的后缘种群之间的差异以及 ABC 分析和物种分布模型的结果表明，这些种群很可能是末次盛冰期的遗迹。然而，尽管长期存在，但有效种群规模低、种群间迁移率低和遗传漂变仍然促进了日本西南部 T.standishii 种群的遗传分化，而没有积累独特的等位基因。
Rear-edge populations are of significant scientific interest because they can contain allelic variation not found in core-range populations. However, such populations can differ in their level of genetic diversity and divergence reflecting variation in life-history traits, demographic histories and human impacts. Using 13 EST-microsatellites, we investigated the genetic diversity and differentiation of rear-edge populations of the Japanese endemic conifer Thuja standishii (Gordon) Carr. in southwest Japan from the core-range in northeast Japan. Range-wide genetic differentiation was moderate (Fst = 0.087), with northeast populations weakly differentiated (Fst = 0.047), but harboring high genetic diversity (average population-level Ar = 4.76 and Ho = 0.59). In contrast, rear-edge populations were genetically diverged (Fst = 0.168), but contained few unique alleles with lower genetic diversity (Ar = 3.73, Ho = 0.49). The divergence between rear-edge populations exceeding levels observed in the core-range and results from ABC analysis and species distribution modelling suggest that these populations are most likely relicts of the Last Glacial Maximum. However, despite long term persistence, low effective population size, low migration between populations and genetic drift have worked to promote the genetic differentiation of southwest Japan populations of T. standishii without the accumulation of unique alleles.