Contrasting microsatellite variation between subalpine and western larch, two closely related species with different distribution patterns
Contrasting microsatellite variation between subalpine and western larch, two closely related species with different distribution patterns
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DOI：
10.1111/j.1365-294x.2006.03066.x
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发表时间：
2006-11-01
影响因子：
4.9
通讯作者：
Bousquet, Jean
中科院分区：
文献类型：
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作者：
Khasa, Damase P.;Jaramillo-Correa, Juan P.;Bousquet, Jean
亚高山落叶松（Larix lyallii Parl.）和西部落叶松（Larix occidentalis Nutt.）是北美西部两个近缘物种，在丰度和分布模式上存在差异。测定了亚高山落叶松19个居群和西部落叶松9个居群的7个信息微卫星位点的遗传多样性。对比了两种植物的遗传多样性和群体分化模式。亚高山落叶松总体居群内遗传多样性参数较低(A = 3.2； A(P) = 3.6；H-E = 0.418)高于西部落叶松(A(P) = 5.51；H-E = 0.580)，这种模式可能与历史或人口因素有关。没有观察到种间杂交的证据。亚高山落叶松种群分化（theta = 0.15, R-ST = 0.07）明显高于西部落叶松（theta = 0.05, R-ST = 0.04），与基因流受限程度较高一致。在无限等位基因突变模型的假设下，19个亚高山落叶松种群中有12个种群表现出偏离突变-漂变平衡的迹象，表明该物种在全新世存在种群瓶颈和有效种群规模波动。西部落叶松种群均未明显偏离突变-漂变平衡。对于这两个物种，Mantel的测试揭示了地理距离和遗传距离之间的显著正相关关系，表明距离隔离。在这两个物种中发现了相似的地理结构，这表明每个物种中至少有两个遗传上不同的冰川种群。讨论了基因保护的各种含义。
Subalpine larch (Larix lyallii Parl.) and western larch (Larix occidentalis Nutt.) represent two closely related species with contrasting abundance and distribution patterns in Western North America. Genetic diversity at seven informative microsatellite loci was determined for 19 populations of subalpine larch and nine populations of western larch. Contrasting genetic diversity and patterns of population differentiation were observed between the two species. The overall within-population genetic diversity parameters were lower in subalpine larch (A = 3.2; A(P) = 3.6; H-E = 0.418) than in western larch (A(P) = 5.51; H-E = 0.580), a pattern that is likely related to historical or demographic factors. No evidence of interspecific hybridization was observed. Significantly more population differentiation (theta = 0.15; R-ST = 0.07), consistent with more restricted gene flow, was observed for subalpine larch as compared to western larch (theta = 0.05; R-ST = 0.04). Under the assumption of an infinite allele mutation model, 12 of the 19 subalpine larch populations showed signs of deviation from the mutation-drift equilibrium, which suggests Holocene population bottlenecks and fluctuations in effective population size for this species. None of the western larch populations deviated significantly from the mutation-drift equilibrium. For both species, Mantel's test revealed a significant positive relationship between geographical and genetic distances indicative of isolation by distance. A similar geographical structure was detected in both species, suggesting at least two genetically distinct glacial populations in each species. The various implications for gene conservation are discussed.