Abstract

Polyploidy plays a significant role in the evolution and diversification of flowering plants. In several polyploid complexes, high morphological variability and plasticity coupled with cytogenetic diversity make it difficult to disentangle their evolutionary history. The main goal of this study was to gain insights into the role of whole genome duplications as one of the factors shaping the evolution of flowering plants. Linum suffruticosum s.l. has been described as a polyploid complex, with high morphological variability, but nothing is known about current cytogeographical patterns. We investigated cytotype diversity and distribution patterns in 151 populations covering most of the distribution range, in the Iberian Peninsula, south-eastern France, north-western Italy and Morocco, using flow cytometric analyses complemented with chromosome counts. A high cytogenetic diversity was found with five major cytotypes being detected (diploids, tetraploids, hexaploids, octoploids and decaploids) and with new ploidy levels being reported for the first time. The different ploidies were distributed parapatrically, with geographical structure and several contact zones. Most of the populations comprised one cytotype, but a few mixed-ploidy populations were observed. Our results suggest that whole genome duplications are one of the key mechanisms, alone or together with hybridization, governing the diversification of L. suffruticosum s.l. Genome size and/or chromosome counts might be useful tools for identifying specimens of L. suffruticosum s.l. Also, geographical overlap and high cytogenetic diversity suggest multiple origins of the polyploids. The diversity observed here has been mostly neglected to date and should be accounted when studying the biosystematics of this complex.

中文翻译：

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多倍体复合物Linum suffruticosum sl（亚麻科）中的细胞遗传多样性

摘要

多倍体在开花植物的进化和多样化中起着重要作用。在几种多倍体复合物中，高形态变异性和可塑性以及细胞遗传学多样性使得难以区分它们的进化历史。这项研究的主要目的是深入了解全基因组重复是影响开花植物进化的因素之一的作用。亚麻。已经将其描述为具有高形态变异性的多倍体复合物，但是对于当前的细胞地理模式一无所知。我们使用流式细胞仪分析并辅以染色体计数，调查了伊比利亚半岛，法国东南部，意大利西北部和摩洛哥的151个人口中大多数分布范围的细胞类型多样性和分布模式。发现了高度的细胞遗传学多样性，检测到五种主要的细胞类型（二倍体，四倍体，六倍体，八倍体和十倍体），并且首次报道了新的倍性水平。不同的倍性分布于父系，具有地理结构和几个接触区。大多数种群包含一种细胞型，但是观察到少数混合倍性种群。L. suffruticosum sl基因组大小和/或染色体计数可能是鉴定L. suffruticosum sl标本的有用工具。同样，地理上的重叠和高细胞遗传学多样性表明多倍体的多种起源。迄今为止，这里观察到的多样性几乎被忽略，在研究该复合体的生物系统学时应予以考虑。