Valdés-Florido Ana, Valcárcel Virginia, Maguilla Enrique, Díaz-Lifante Zoila, Andrés-Camacho Cristina, Zeltner Louis, Coca-de-la-Iglesia Marina, Medina Nagore G, Arroyo Juan, Escudero Marcial
Department of Plant Biology and Ecology, Faculty of Biology, University of Seville, Seville, Spain.
Departamento de Biología, Universidad Autónoma de Madrid, Madrid, Spain.
Front Plant Sci. 2024 Aug 9;15:1439985. doi: 10.3389/fpls.2024.1439985. eCollection 2024.
Speciation and diversification patterns in angiosperms are frequently shaped by niche evolution. Hill is a Mediterranean genus with ca. 25 species, of which 60% are polyploids (tetra- and hexaploids), distributed mainly in the Mediterranean Basin and in areas with temperate and arid climates of Asia, Europe, North-Central Africa and North America. The evolutionary history of this genus has been studied using morphological, biogeographical and molecular approaches, but its climatic niche characterization and its relation with genome evolution (chromosome number and ploidy level) has not been addressed yet. Thus, this study aims to identify the role of the evolution of climatic niche, ploidy level, life cycle and floral traits in the diversification of . Climatic niche characterization involved estimating present climate preferences using quantitative data and reconstructing ancestral niches to evaluate climatic niche shifts. The evolution of climatic niche towards selective optima determined by ploidy level (three ploidy levels) and different binary traits (polyploidy, floral size, floral display, herkogamy and life cycle) was addressed under the Ornstein-Uhlenbeck model. Chromosome number evolution was inferred using the ChromoSSE model, testing if changes are clado- or anagenetic. Chromosome number evolution and its link with cladogenesis, life cycle and floral traits was modeled on the phylogeny. The reconstruction of the ancestral niches shows that originated in a mild climate and diversified to both humid and cold as well as to dry and warmer climates. Niche conservatism was estimated in the climatic niche of the ancestors, while the climatic niche of the current taxa experienced transitions from their ancestors' niche. Besides, the evolution of climatic niche towards multiple selective optima determined by the studied traits was supported, life cycle optima receiving the highest support. The reconstruction of chromosome number transitions shows that the rate of speciation process resulting from chromosomal changes (chromosomal cladogenesis) is similar to that of non-chromosomal cladogenesis. Additionally, dependent evolution of floral size, floral display and herkogamy with chromosome number variation was supported. In conclusion, polyploidization is a crucial process in the Mediterranean region that assisted speciation and diversification into new areas with different climates, entailing niche shifts and evolution of reproductive strategies.
被子植物的物种形成和多样化模式通常受到生态位进化的影响。希尔是一个地中海属，约有25个物种，其中60%是多倍体（四倍体和六倍体），主要分布在地中海盆地以及亚洲、欧洲、中非和北美具有温带和干旱气候的地区。该属的进化历史已通过形态学、生物地理学和分子方法进行了研究，但其气候生态位特征及其与基因组进化（染色体数目和倍性水平）的关系尚未得到探讨。因此，本研究旨在确定气候生态位、倍性水平、生命周期和花部性状的进化在该属多样化过程中的作用。气候生态位特征包括利用定量数据估计当前的气候偏好，并重建祖先生态位以评估气候生态位的变化。在奥恩斯坦 - 乌伦贝克模型下，探讨了由倍性水平（三个倍性水平）和不同二元性状（多倍体、花大小、花展示、雌雄异位和生命周期）决定的气候生态位向选择性最优状态的进化。使用ChromoSSE模型推断染色体数目进化，测试变化是分支发生还是前进发生。在系统发育树上对染色体数目进化及其与分支发生、生命周期和花部性状的联系进行建模。祖先生态位的重建表明，该属起源于温和气候，随后多样化到湿润和寒冷以及干燥和温暖的气候。在祖先的气候生态位中估计了生态位保守性，而当前分类群 的气候生态位经历了从其祖先生态位的转变。此外，支持了由所研究性状决定的气候生态位向多个选择性最优状态的进化，生命周期最优状态得到的支持最高。染色体数目转变的重建表明，由染色体变化导致物种形成过程的速率（染色体分支发生）与非染色体分支发生的速率相似。此外，支持了花大小、花展示和雌雄异位与染色体数目变异的依赖性进化。总之，多倍体化是地中海地区的一个关键过程，它有助于物种形成并向具有不同气候的新区域多样化，导致生态位转移和繁殖策略的进化。
