Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China.
Mol Ecol. 2012 Sep;21(18):4631-45. doi: 10.1111/j.1365-294X.2012.05707.x. Epub 2012 Jul 19.
Both deterministic and stochastic forces determine the representation and frequency of floral morphs in heterostylous plant populations. Phylogeographic analysis of molecular variation can provide information on the role of historical factors, including founder events, in affecting population morph structure. Here, we investigate geographical patterns of floral morph variation in a distylous shrub Luculia pinceana (Rubiaceae) by examining the relations between floral polymorphism and molecular (cpDNA and microsatellite) variation in 25 populations sampled throughout the distribution of the species in southwest China and adjacent countries. In 19 of the 25 populations, the frequency of floral morphs was not significantly different from the expected 1:1 ratio. The remaining populations were either L-morph biased (2) or monomorphic (4) for this form and were morphologically differentiated from the remaining populations in several floral traits, that is, corolla tube length, sex organ position and stigma-anther separation. Phylogeographic analysis supports the hypothesis that L. pinceana was initially split into west-central and eastern lineages in the Early Pleistocene (~1.982 Mya). A centrally located lineage composed of morph-biased and monomorphic populations appears to have been subsequently derived from the west-central lineage, perhaps by a founder event after the last glacial maximum. Hypotheses to explain why these populations have not returned to equilibrium morph frequencies are considered.
无论是确定性力量还是随机性力量，都决定了异型花柱植物种群中花形态的表现和频率。分子变异的系统地理学分析可以提供有关历史因素（包括奠基者事件）在影响种群形态结构方面的作用的信息。在这里，我们通过检查在西南中国及其邻国的物种分布范围内采样的 25 个种群的花形态多态性与分子（cpDNA 和微卫星）变异之间的关系，研究了异型花柱灌木 Luculia pinceana（茜草科）的花形态变异的地理格局。在 25 个种群中的 19 个种群中，花形态的频率与预期的 1:1 比例没有显著差异。其余的种群要么偏向 L 形态（2 个），要么为这种形式的单态（4 个），并且在几个花特征方面与其余种群在形态上有所区别，即花冠管长度、性器官位置和柱头-花药分离。系统地理学分析支持这样的假设，即 L. pinceana 在更新世早期（约 1.982 Mya）最初分为中西部和东部谱系。一个由形态偏向和单态种群组成的中心谱系似乎是从中西部谱系衍生而来的，可能是在末次冰期之后由奠基者事件引起的。考虑了一些解释为什么这些种群没有恢复到平衡形态频率的假说。
