Kang Ming, Tao Junjie, Wang Jing, Ren Chen, Qi Qingwen, Xiang Qiu-Yun, Huang Hongwen
Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
University of Chinese Academy of Sciences, Beijing, China.
New Phytol. 2014 Jun;202(4):1371-1381. doi: 10.1111/nph.12726. Epub 2014 Feb 17.
Genome size variation is of fundamental biological importance and has been a longstanding puzzle in evolutionary biology. Several hypotheses for genome size evolution including neutral, maladaptive, and adaptive models have been proposed, but the relative importance of these models remains controversial. Primulina is a genus that is highly diversified in the Karst region of southern China, where genome size variation and the underlying evolutionary mechanisms are poorly understood. We reconstructed the phylogeny of Primulina using DNA sequences for 104 species and determined the genome sizes of 101 species. We examined the phylogenetic signal in genome size variation, and tested the fit to different evolutionary models and for correlations with variation in latitude and specific leaf area (SLA). The results showed that genome size, SLA and latitudinal variation all displayed strong phylogenetic signals, but were best explained by different evolutionary models. Furthermore, significant positive relationships were detected between genome size and SLA and between genome size and latitude. Our study is the first to investigate genome size evolution on such a comprehensive scale and in the Karst region flora. We conclude that genome size in Primulina is phylogenetically conserved but its variation among species is a combined outcome of both neutral and adaptive evolution.
基因组大小变异具有重要的生物学意义，长期以来一直是进化生物学中的一个谜题。人们提出了几种关于基因组大小进化的假说，包括中性、非适应性和适应性模型，但这些模型的相对重要性仍存在争议。报春苣苔属在中国南方喀斯特地区高度多样化，然而该地区的基因组大小变异及其潜在的进化机制却鲜为人知。我们利用104个物种的DNA序列重建了报春苣苔属的系统发育，并测定了101个物种的基因组大小。我们研究了基因组大小变异中的系统发育信号，测试了其与不同进化模型的拟合情况以及与纬度和比叶面积（SLA）变异的相关性。结果表明，基因组大小、SLA和纬度变异均显示出强烈的系统发育信号，但由不同的进化模型能得到最好的解释。此外，还检测到基因组大小与SLA之间以及基因组大小与纬度之间存在显著的正相关关系。我们的研究首次在如此全面的规模上以及喀斯特地区植物区系中研究基因组大小的进化。我们得出结论，报春苣苔属的基因组大小在系统发育上是保守的，但其物种间的变异是中性进化和适应性进化共同作用的结果。
