Department of Plant Pathology, Kansas State University, Manhattan, Kansas, United States of America.
PLoS One. 2011 Apr 12;6(4):e17641. doi: 10.1371/journal.pone.0017641.
Environmental variables such as moisture availability are often important in determining species prevalence and intraspecific diversity. The population genetic structure of dominant plant species in response to a cline of these variables has rarely been addressed. We evaluated the spatial genetic structure and diversity of Andropogon gerardii populations across the U.S. Great Plains precipitation gradient, ranging from approximately 48 cm/year to 105 cm/year.
METHODOLOGY/PRINCIPAL FINDINGS: Genomic diversity was evaluated with AFLP markers and diversity of a disease resistance gene homolog was evaluated by PCR-amplification and digestion with restriction enzymes. We determined the degree of spatial genetic structure using Mantel tests. Genomic and resistance gene homolog diversity were evaluated across prairies using Shannon's index and by averaging haplotype dissimilarity. Trends in diversity across prairies were determined using linear regression of diversity on average precipitation for each prairie. We identified significant spatial genetic structure, with genomic similarity decreasing as a function of distance between samples. However, our data indicated that genome-wide diversity did not vary consistently across the precipitation gradient. In contrast, we found that disease resistance gene homolog diversity was positively correlated with precipitation.
Prairie remnants differ in the genetic resources they maintain. Selection and evolution in this disease resistance homolog is environmentally dependent. Overall, we found that, though this environmental gradient may not predict genomic diversity, individual traits such as disease resistance genes may vary significantly.
环境变量（如水分可用性）通常在确定物种的流行程度和种内多样性方面非常重要。对于这些变量的梯度，主导植物物种的种群遗传结构很少被涉及。我们评估了美国大平原降水梯度上的 A. gerardii 种群的空间遗传结构和多样性，范围从大约 48 厘米/年到 105 厘米/年。
方法/主要发现：使用 AFLP 标记评估基因组多样性，并使用 PCR 扩增和限制性内切酶消化评估抗病基因同源物的多样性。我们使用 Mantel 检验确定空间遗传结构的程度。使用 Shannon 指数和平均单倍型差异评估草原上的基因组和抗病基因同源物多样性。通过对每个草原的平均降水量进行多样性线性回归来确定草原上多样性的趋势。我们确定了显著的空间遗传结构，随着样本之间距离的增加，基因组相似性降低。然而，我们的数据表明，全基因组多样性并没有一致地随降水梯度变化。相比之下，我们发现抗病基因同源物多样性与降水呈正相关。
草原残余物在它们所维持的遗传资源方面存在差异。这种抗病同源物的选择和进化是环境依赖的。总的来说，我们发现尽管这种环境梯度可能无法预测基因组多样性，但个体特征（如抗病基因）可能会有很大的变化。
