Polyploidization of the plant genome affects the phenotype of individuals including their morphology, i.e. size and form. In autopolyploids, we expect mainly nucleotypic effects, from a number of monoploid genomes (i.e. chromosome sets) or genome size, seen from an increase in size or dimension of the polyploids compared with the diploids (or lower ploids). To identify nucleotypic effects, confounding effects of hybridity (observed in allopolyploids), postpolyploidization processes or environmental effects need to be considered. We morphometrically analysed five ploidy cytotypes of the sexual-apomictic species Potentilla puberula cultivated ex situ under the same experimental conditions. Sexuals are mainly tetraploid, while higher ploidy (penta- to octoploidy) is typically associated with the expression of apomixis. The cytotypes likely arose via autopolyploidization although historic involvement of another species in the origin of apomicts cannot be fully ruled out, suggested by a slight molecular differentiation among reproductive modes. We (i) revisited molecular differentiation using amplified fragment length polymorphisms and performed a morphometric analysis to test (ii) if cytotypes are morphologically differentiated from each other and (iii) if the size of individuals is related to their ploidy. Weak molecular differentiation of sexual versus apomictic individuals was confirmed. Cytotypes and reproductive modes were also morphologically poorly differentiated from each other, i.e. apomicts largely resampled the variation of the sexuals and did not exhibit a unique morphology. Overall size of individuals increased moderately but significantly with ploidy (ca. 14 % in the comparison of octo- with tetraploids). The results support an autopolyploid origin of the P. puberula apomicts and suggest a nucleotypic effect on overall plant size. We discuss taxonomic consequences of the results in the context of data on reproductive relationships among cytotypes and their ecological preferences and evolutionary origin, and conclude that cytotypes are best treated as intraspecific variants within a single species.

中文翻译：

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同源多倍体的形态计量学：有性无融合生殖细胞型之间的微不足道的分化。


植物基因组的多倍化影响个体的表型，包括其形态，即大小和形式。在同源多倍体中，我们预计主要是来自许多单倍体基因组（即染色体组）或基因组大小的核型效应，从多倍体的大小或尺寸与二倍体（或较低倍体）相比的增加看出。为了识别核型效应，需要考虑杂交的混杂效应（在异源多倍体中观察到）、多倍化后过程或环境影响。我们对在相同实验条件下异位培养的有性无融合生殖物种委陵菜的五种倍性细胞型进行了形态计量学分析。有性生物主要是四倍体，而更高倍性（五倍体至八倍体）通常与无融合生殖的表达相关。细胞型可能是通过同体多倍体化产生的，尽管不能完全排除另一个物种在无融合生殖起源中的历史参与，这由生殖模式之间的轻微分子差异表明。我们（i）使用扩增片段长度多态性重新审视分子分化，并进行形态计量分析以测试（ii）细胞型是否在形态上彼此区分，以及（iii）个体的大小是否与其倍性相关。证实了有性生殖个体与无融合生殖个体的弱分子分化。细胞型和生殖模式在形态上彼此之间的差异也很差，即无融合生殖体很大程度上重新采样了两性的变异，并且没有表现出独特的形态。倍性个体的总体大小适度但显着增加（八倍体与四倍体相比约增加 14%）。结果支持 P. 的同源多倍体起源。 柔毛无融合生殖，表明核型对植物整体大小有影响。我们在细胞型之间的繁殖关系及其生态偏好和进化起源的数据背景下讨论了结果的分类学后果，并得出结论，细胞型最好被视为单个物种内的种内变异。