Ramírez-Barahona Santiago, González Clementina, González-Rodríguez Antonio, Ornelas Juan Francisco
Departamento de Biología Evolutiva, Instituto de Ecología, AC (INECOL), Carretera antigua a Coatepec No. 351, El Haya, Xalapa, Veracruz, 91070, Mexico.
CONACyT-Instituto de Investigaciones sobre los Recursos Naturales, Universidad Michoacana de San Nicolás de Hidalgo, Av. San Juanito Itzícuaro s/n, Nueva Esperanza, Morelia, Michoacán, 58330, Mexico.
New Phytol. 2017 Jun;214(4):1751-1761. doi: 10.1111/nph.14471. Epub 2017 Feb 16.
The prevalent view on genetic structuring in parasitic plants is that host-race formation is caused by varying degrees of host specificity. However, the relative importance of ecological niche divergence and host specificity to population differentiation remains poorly understood. We evaluated the factors associated with population differentiation in mistletoes of the Psittacanthus schiedeanus complex (Loranthaceae) in Mexico. We used genetic data from chloroplast sequences and nuclear microsatellites to study population genetic structure and tested its association with host preferences and climatic niche variables. Pairwise genetic differentiation was associated with environmental and host preferences, independent of geography. However, environmental predictors appeared to be more important than host preferences to explain genetic structure, supporting the hypothesis that the occurrence of the parasite is largely determined by its own climatic niche and, to a lesser degree, by host specificity. Genetic structure is significant within this mistletoe species complex, but the processes associated with this structure appear to be more complex than previously thought. Although host specificity was not supported as the major determinant of population differentiation, we consider this to be part of a more comprehensive ecological model of mistletoe host-race formation that incorporates the effects of climatic niche evolution.
关于寄生植物遗传结构的普遍观点是，宿主种族的形成是由不同程度的宿主特异性引起的。然而，生态位分化和宿主特异性对种群分化的相对重要性仍知之甚少。我们评估了与墨西哥的 Schiedeanus 桑寄生复合体（桑寄生科）槲寄生种群分化相关的因素。我们利用叶绿体序列和核微卫星的遗传数据来研究种群遗传结构，并测试其与宿主偏好和气候生态位变量的关联。成对遗传分化与环境和宿主偏好相关，与地理无关。然而，环境预测因子似乎比宿主偏好对解释遗传结构更重要，这支持了这样一种假设，即寄生虫的出现很大程度上由其自身的气候生态位决定，在较小程度上由宿主特异性决定。在这个槲寄生物种复合体内遗传结构是显著的，但与这种结构相关的过程似乎比以前认为的更复杂。虽然宿主特异性不被支持作为种群分化的主要决定因素，但我们认为这是槲寄生宿主种族形成更全面生态模型的一部分，该模型纳入了气候生态位进化的影响。
