Amaranthus palmeri populations can evolve life-history traits despite its high levels of genetic diversity and gene flow. However, it was not known whether those differences were due to selection or other evolutionary processes. We used microsatellite markers to quantify genetic differentiation among 10 Amaranthus palmeri populations and determined whether the differences in life-history traits among the populations could be attributed to selection. Genetic differentiation was small (Φ_ST = 0.093), indicating that there were high rates of gene flow among populations. AMOVA showed that only 9% of the genetic variability was explained by variation among populations and 90% was found within populations. Using Φ_ST as a surrogate for F_ST in the Q_ST−F_ST analysis, we confirmed that most traits followed the same pattern as neutral markers and were not under selection. However, important traits for weediness such as plant height, dry weight and nitrogen use efficiency were under selection. These results provide evidence that selection forces in agroecosystems can increase weediness in A. palmeri, and that those forces should be identified to develop strategies to counter them when possible.

中文翻译：

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Amaranthus palmeri S. Watson 生活史性状适应性的种群和数量遗传分析

尽管Amaranthus palmeri种群具有高水平的遗传多样性和基因流，但它仍然可以进化出生活史特征。但是，尚不清楚这些差异是由于选择还是其他进化过程造成的。我们使用微卫星标记来量化 10 个Amaranthus palmeri种群之间的遗传分化，并确定种群间生活史特征的差异是否可归因于选择。遗传分化很小（Φ _ST  = 0.093），表明种群间基因流动率很高。AMOVA 表明，只有 9% 的遗传变异是由种群间的变异解释的，而 90% 是在种群内发现的。使用 Φ _ST作为 F _ST的替代在 Q _ST -F _ST分析中，我们确认大多数性状遵循与中性标记相同的模式并且没有被选择。然而，对杂草的重要性状，如株高、干重和氮肥利用效率正在选择中。这些结果提供了证据，表明农业生态系统中的选择力会增加A. palmeri 的杂草，并且应确定这些力以制定策略以在可能的情况下应对它们。