Departamento de Conservación de la Biodiversidad, El Colegio de la Frontera Sur, Villahermosa. Carretera Villahermosa-Reforma km 15.5 Ranchería El Guineo 2ª sección, 86280 Villahermosa, Tabasco, Mexico; Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México. Circuito Exterior s/n Anexo al Jardín Botánico, 04510 Ciudad de México, Mexico; UBIPRO, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Av. de los Barrios #1, Col. Los Reyes Iztacala, 54090 Tlanepantla, Edo. de Mex, Mexico.
Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México. Circuito Exterior s/n Anexo al Jardín Botánico, 04510 Ciudad de México, Mexico.
Mol Phylogenet Evol. 2018 Nov;128:38-54. doi: 10.1016/j.ympev.2018.07.016. Epub 2018 Jul 21.
Knowledge of the role of geographical and ecological events associated to the divergence process of wild progenitors is important to understand the process of domestication. We analysed the temporal, spatial and ecological patterns of the diversification of Cucurbita, an American genus of worldwide economic importance. We conducted a phylogenetic analysis based on six chloroplast regions (5907 bp) to estimate diversification rates and dates of divergence between taxa. This is the first phylogenetic study to include C. radicans, a wild species that is endemic to the Trans Mexican Volcanic Belt. We performed analysis of ancestral area reconstruction and paleoreconstructions of species distribution models to understand shifts in wild species ranges. We used principal component analysis (PCA) and multivariate analysis of variance (MANOVA) to evaluate the environmental differentiation among taxa within each clade. The phylogenetic analyses showed good support for at least six independent domestication events in Cucurbita. The genus Cucurbita showed a time of divergence of 11.24 Ma (6.88-17 Ma 95% HDP), and the dates of divergence between taxa within each group ranged from 0.35 to 6.58 Ma, being the divergence between C. lundelliana and C. okeechobeensis subsp. martinezii the most recent. The diversification rate of the genus was constant through time. The diversification of most wild taxa occurred during the Pleistocene, and its date of divergence is concordant with the dates of divergence reported for specialized bees of the genera Xenoglossa and Peponapis, suggesting a process of coevolution between Cucurbita and their main pollinators that should be further investigated. Tests of environmental differentiation together with ancestral area reconstruction and species distribution models past projections suggest that divergence was promoted by the onset of geographic barriers and secondary range contraction and by expansion related to glacial-interglacial cycles.
了解与野生祖先分化过程相关的地理和生态事件的作用对于理解驯化过程很重要。我们分析了具有全球经济重要性的美洲属南瓜属的多样化的时间、空间和生态模式。我们进行了基于六个叶绿体区域（5907bp）的系统发育分析，以估计分类群之间的多样化速率和分化日期。这是第一项包括特有于 Trans Mexican Volcanic Belt 的野生种 C. radicans 的系统发育研究。我们进行了祖先区域重建和物种分布模型的古重建分析，以了解野生物种范围的变化。我们使用主成分分析（PCA）和多元方差分析（MANOVA）来评估每个分支内分类群之间的环境差异。系统发育分析为 Cucurbita 中的至少六次独立驯化事件提供了很好的支持。南瓜属的分化时间为 11.24 Ma（6.88-17 Ma 95% HDP），每个组内分类群之间的分化日期范围为 0.35 至 6.58 Ma，C. lundelliana 和 C. okeechobeensis subsp. martinezii 之间的分化最近。属的多样化速率随时间保持不变。大多数野生类群的多样化发生在更新世，其分化日期与 Xenoglossa 和 Peponapis 等专门蜜蜂的分化日期一致，表明南瓜与其主要传粉者之间存在共同进化过程，这需要进一步研究。环境差异的测试以及祖先区域重建和物种分布模型过去的预测表明，地理障碍的出现、次生范围收缩以及与冰期-间冰期循环相关的扩张促进了分化。
