Hutang Ge-Ran, Tong Yan, Zhu Xun-Ge, Gao Li-Zhi
Germplasm Bank of Wild Species in Southwestern China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China.
University of Chinese Academy of Sciences, Beijing, China.
Front Plant Sci. 2023 Mar 13;14:1066925. doi: 10.3389/fpls.2023.1066925. eCollection 2023.
Biologists have long debated the drivers of the genome size evolution and variation ever since Darwin. Assumptions for the adaptive or maladaptive consequences of the associations between genome sizes and environmental factors have been proposed, but the significance of these hypotheses remains controversial. is a large genus in the grass family and is often used as crop or forage during the dry seasons. The wide range and complex ploidy levels make an excellent model for investigating how the genome size variation and evolution is associated with environmental factors and how these changes can ben interpreted.
We reconstructed the phylogeny and estimated genome sizes through flow cytometric analyses. Phylogenetic comparative analyses were performed to explore how genome size variation and evolution is related to their climatic niches and geographical ranges. The genome size evolution and environmental factors were examined using different models to study the phylogenetic signal, mode and tempo throughout evolutionary history.
Our results support the monophyly of . The genome sizes in ranged from ~0.66 pg to ~3.80 pg. We found that a moderate phylogenetic conservatism existed in terms of the genome sizes but was absent from environmental factors. In addition, phylogeny-based associations revealed close correlations between genome sizes and precipitation-related variables, indicating that the genome size variation mainly caused by polyploidization may have evolved as an adaptation to various environments in the genus .
This is the first study to take a global perspective on the genome size variation and evolution in the genus . Our results suggest that the adaptation and conservatism are manifested in the genome size variation, allowing the arid species of to spread the xeric area throughout the world.
自达尔文时代以来，生物学家就长期争论基因组大小进化和变异的驱动因素。关于基因组大小与环境因素之间关联的适应性或非适应性后果的假设已经提出，但这些假设的重要性仍存在争议。[该属名未给出，暂用“该属”代替]是禾本科中的一个大属，在旱季常被用作作物或饲料。其广泛的分布范围和复杂的倍性水平使其成为研究基因组大小变异和进化如何与环境因素相关联以及这些变化如何被解释的极佳模型。
我们通过流式细胞术分析重建了该属的系统发育并估计了基因组大小。进行了系统发育比较分析，以探索基因组大小变异和进化如何与其气候生态位和地理范围相关。使用不同模型研究了整个进化历史中的系统发育信号、模式和节奏，以检验基因组大小进化和环境因素。
我们的结果支持该属的单系性。该属的基因组大小范围从约0.66皮克到约3.80皮克。我们发现，就基因组大小而言存在适度的系统发育保守性，但环境因素不存在。此外，基于系统发育的关联揭示了基因组大小与降水相关变量之间的密切相关性，表明主要由多倍体化引起的基因组大小变异可能已经进化为对该属各种环境的适应。
这是第一项从全球视角研究该属基因组大小变异和进化的研究。我们的结果表明，适应性和保守性体现在基因组大小变异中，使该属的干旱物种能够在全球干旱地区传播。
