Malagasy Dracaena (Ruscaceae) are divided into four species and 14 varieties, all of them showing a high level of morphological diversity and a putatively artefactual circumscription. In order to reveal relationships between those entangled entities, a span of Malagasy Dracaena were sampled and analyzed using cpDNA sequences and AFLP. The cpDNA analyses resolved three biogeographic clades that are mostly inconsistent with morphology, since similar phenotypes are found across the three clades. Bayesian inference clustering analyses based on the AFLP were not in accordance with the cpDNA analysis. This result might be explained by (1) a recent origin of the Malagasy species of Dracaena with an incomplete sorting of chloroplast lineages; (2) a high amount of hybridizations; (3) a complex migration pattern. Interestingly, when the AFLP are analyzed using the parsimony criterion, a trend towards a directional evolution of inflorescence types and ecological features was observed. This might be considered either as phenotypic plasticity and/or as the result of fast evolution in flower characters according to habitat preferences. Overall, our results point to the difficulty of defining evolutionarily significant units in Malagasy Dracaena, emphasizing the complex speciation processes taking place in tropical regions.

中文翻译：

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马达加斯加龙血树 Vand。ex L.（Ruscaceae）：在小进化尺度上对形态特征和空间遗传结构之间差异的调查

马达加斯加龙血树 (Ruscaceae) 分为 4 个物种和 14 个变种，所有这些都表现出高度的形态多样性和假定的人工限制。为了揭示这些纠缠实体之间的关系，使用 cpDNA 序列和 AFLP 对马达加斯加龙血树进行了采样和分析。cpDNA 分析解决了三个与形态学不一致的生物地理进化枝，因为在这三个进化枝中发现了相似的表型。基于 AFLP 的贝叶斯推理聚类分析与 cpDNA 分析不一致。这一结果可能是由（1）最近起源的马达加斯加龙血树属物种的叶绿体谱系分类不完整；(2) 大量杂交；(3)复杂的迁移模式。有趣的是，当使用简约标准分析 AFLP 时，观察到花序类型和生态特征的定向进化趋势。这可能被认为是表型可塑性和/或根据栖息地偏好的花卉特征快速进化的结果。总体而言，我们的结果表明很难在马达加斯加龙血树中定义具有进化意义的单位，强调热带地区发生的复杂物种形成过程。