Soliva M, Widmer A
Int J Plant Sci. 1999 Sep;160(5):897-905. doi: 10.1086/314192.
Gymnadenia conopsea s.l. is a common orchid in central Europe, where early- and late-flowering populations can be distinguished. The early-flowering form is recognized as subspecies conopsea and the late-flowering form as subspecies densiflora. The two subspecies can occur in sympatry, but their flowering periods are separated. We investigated whether early- and late-flowering subspecies are genetically differentiated, whether they diverged once or repeatedly, and we tried to identify potential evolutionary forces involved in the divergence of the two subspecies. We used genetic markers to estimate genetic divergence within and among populations of early- and late-flowering G. conopsea, and to reconstruct their evolutionary history. In addition, we assessed morphological variation between subspecies. Allozyme variation indicated that subspecies conopsea was significantly more variable than ssp. densiflora and that gene flow among populations of ssp. conopsea was higher than among populations of ssp. densiflora. Gene flow between subspecies was low, indicating that the difference in flowering phenology represented an effective barrier to gene flow. A neighbor-joining tree based on allozyme frequencies indicated that early- and late- flowering populations did not diverge repeatedly in sympatry. Levels of cpDNA variation were generally low, even between G. conopsea s.l. and Gymnadenia odoratissima, chosen as an outgroup. Four cpDNA haplotypes were found, which differed only in the number of microsatellite repeats. Their distribution among subspecies of G. conopsea s.l. and G. odoratissima indicates that microsatellite haplotypes have evolved repeatedly, and their occurrence in different taxa thus represents a homoplasy. Floral characters were variable within and among populations and subspecies but did not consistently separate early- from late-flowering populations. A weak separation between subspecies was found in vegetative characters that presumably reflected habitat and competitive differences experienced by early- and late-flowering populations.
广义的康诺普手参是中欧一种常见的兰花，在那里可以区分早花和晚花种群。早花形态被认定为康诺普手参亚种，晚花形态被认定为密花手参亚种。这两个亚种可能同域分布，但它们的花期是分开的。我们研究了早花和晚花亚种是否在基因上存在分化，它们是一次还是多次发生分歧，并且我们试图确定这两个亚种分歧过程中涉及的潜在进化力量。我们使用遗传标记来估计早花和晚花康诺普手参种群内部和种群之间的遗传差异，并重建它们的进化历史。此外，我们评估了亚种之间的形态变异。等位酶变异表明，康诺普手参亚种的变异性明显高于密花手参亚种，并且康诺普手参亚种种群之间的基因流高于密花手参亚种种群之间的基因流。亚种之间的基因流较低，这表明花期物候差异是基因流的有效障碍。基于等位酶频率的邻接树表明，早花和晚花种群在同域分布中并非多次发生分歧。叶绿体DNA（cpDNA）变异水平总体较低，即使在作为外类群的广义康诺普手参与香手参之间也是如此。发现了四种cpDNA单倍型，它们仅在微卫星重复次数上有所不同。它们在广义康诺普手参亚种和香手参中的分布表明，微卫星单倍型已经多次进化，因此它们在不同分类群中的出现代表了一种同塑现象。花的特征在种群和亚种内部及之间存在变异，但并没有始终如一地将早花种群与晚花种群区分开来。在营养特征方面发现亚种之间存在微弱的区分，这可能反映了早花和晚花种群所经历的栖息地和竞争差异。
