Key message Discovery of the first case of allotriploid juniper in a wild population in the French Alps where the parental species occurs in sympatry. & Context Interspecific hybridization and polyploidy are important evolutionary phenomena in vascular plants. Natural hybridization between species living in sympatry can sometimes occur. Less frequent are successful hybridizations between species having different ploidy levels. At Saint Crépin location (French Alps), where sympatry between the tetraploid Juniperus thurifera and the diploid Juniperus sabina occurs, three individuals with an atypical morphology have been observed. & Aims Prospect interspecific hybrids and interspecific genetic introgression occurrence. & Methods Flow cytometry was employed to screen ploidy levels. Four chloroplast markers, nrDNA (ITS), and AFLP markers were used to unravel hybridization and potential introgression events. Variability of pollen size and morphology was assessed to have a first insight on the regularity of microsporogenesis in hybrids. & Results The three putative hybrids were shown to be triploids. Molecular data demonstrated that these individuals were hybrids originated from a cross between J. sabina and J. thurifera and suggested that a backcross at least with J. thurifera is possible. Male triploid hybrids produced heterogeneous pollen and displayed evidence of irregularity in the microsporogenesis. & Conclusion This study sheds light on a rare case of hybridization in a natural sympatric population of two Juniperus species with different ploidy levels. This mechanism might have been an important driver for the evolution and diversification of this

中文翻译：

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在法国阿尔卑斯山的同域地区杜松和杜鹃花异源三倍体杂交的第一个证据

关键信息 在法国阿尔卑斯山的野生种群中发现第一例同种异源三倍体杜松，其中亲本物种共存。& 背景 种间杂交和多倍体是维管植物中重要的进化现象。有时会发生共生的物种之间的自然杂交。具有不同倍性水平的物种之间成功杂交的频率较低。在 Saint Crépin 位置（法国阿尔卑斯山），四倍体杜松和二倍体杜松发生共生，观察到三个具有非典型形态的个体。& 目的 展望种间杂种和种间遗传基因渗入的发生。& 方法流式细胞术用于筛选倍性水平。四个叶绿体标记，nrDNA (ITS)，和 AFLP 标记用于解开杂交和潜在的基因渗入事件。评估花粉大小和形态的变异性，以初步了解杂种中小孢子发生的规律。& 结果 三个推定的杂种被证明是三倍体。分子数据表明，这些个体是源自麻木和麻花的杂交种，并表明至少与麻花进行回交是可能的。雄性三倍体杂种产生异质花粉并显示出小孢子发生不规则的证据。& 结论 本研究揭示了在具有不同倍性水平的两种杜松属的自然同域种群中发生的罕见杂交案例。这种机制可能是这种进化和多样化的重要驱动力