Štubňová Eliška, Hodálová Iva, Kučera Jaromír, Mártonfiová Lenka, Svitok Marek, Slovák Marek
Plant Science and Biodiversity Centre, Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84523 Bratislava, Slovak Republic.
Pavol Jozef Šafárik University, Botanical Garden, Mánesova 23, SK-04352 Košice, Slovak Republic.
Am J Bot. 2017 Aug;104(8):1241-1253. doi: 10.3732/ajb.1700153.
Detailed knowledge about the karyological diversity of organisms undoubtedly represents one of the crucial steps toward a better understanding of their evolutionary trends and history. We investigated the cytotype and absolute genome size (AGS) patterns in the European mountain-dwelling genus Soldanella (Primulaceae) in light of its geographic distribution and ecological diversification.
Our chromosome number survey was based on 34 newly determined and 125 previously published chromosome counts. AGS was estimated on the basis of propidium iodide (PI) flow cytometry (299 individuals, 110 populations).
We confirmed the existence of two cytotypes with the same ploidy level, i.e., euploid 2n = 40 and dysploid 2n = 38. The overall infrageneric AGS variation ranged between 2.97 and 3.99 pg (25.6% variation). The 2n = 40 cytotype harbors a modest amount of continuous AGS variation. With regard to its distribution area and ecology, the cytotype is ubiquitous. By contrast, the 2n = 38 cytotype was detected only in six forest-dwelling taxa with AGS variation segregated into three discrete, geographically separated groups. The AGS variation of the 2n = 38 cytotype was strongly correlated with elevation and longitude.
Despite the apparent morphological and ecological variation, members of the genus Soldanella have not undergone any pronounced cytotype and AGS diversification during their evolutionary history. The lack of correlation between chromosome numbers and AGS indicates that the evolutionary mechanism behind the origin of the dysploid cytotype 2n = 38 was a chromosomal fusion.
深入了解生物体的核型多样性无疑是更好地理解其进化趋势和历史的关键步骤之一。我们根据欧洲山地植物属雪报春（报春花科）的地理分布和生态分化情况，对其细胞型和绝对基因组大小（AGS）模式进行了研究。
我们的染色体数目调查基于34个新测定的和125个先前发表的染色体计数。基于碘化丙啶（PI）流式细胞术（299个个体，110个种群）估算了AGS。
我们确认了存在两种具有相同倍性水平的细胞型，即整倍体2n = 40和非整倍体2n = 38。属内总体AGS变异范围在2.97至3.99皮克之间（变异率为25.6%）。2n = 40细胞型具有适度的连续AGS变异。就其分布区域和生态而言，该细胞型无处不在。相比之下，仅在6个栖息于森林的分类群中检测到2n = 38细胞型，其AGS变异分为三个离散的、地理上分隔的组。2n = 38细胞型的AGS变异与海拔和经度密切相关。
尽管雪报春属成员在形态和生态上存在明显变异，但其在进化历史中并未经历任何显著的细胞型和AGS多样化。染色体数目与AGS之间缺乏相关性表明，非整倍体细胞型2n = 38起源背后的进化机制是染色体融合。
