Laboratorio de Genómica y Biodiversidad, Departamento de Ciencias Básicas, Universidad del Bío Bío, Casilla, 447 Chillán, Chile.
Proc Natl Acad Sci U S A. 2011 Nov 15;108(46):18743-7. doi: 10.1073/pnas.1108863108. Epub 2011 Nov 7.
Fire is a major disturbance affecting ecosystems worldwide. Phylogenetic studies have shown that the evolution of seed persistence (fire resistance) is associated with fire frequency or severity. However, the existence of specific seed traits resulting from natural selection mediated by fire remains a key question in plant evolution. We evaluated the role of fire in the evolution of seed traits from a microevolutionary perspective, using as a study system a native forb from the Chilean matorral, where fire is a novel, anthropogenic disturbance. We show that anthropogenic fires are shaping the evolution of seed traits such as pubescence and shape. Among-population variation in seed pubescence, shape, and pericarp thickness was strongly associated with fire frequency, and within a population, fire selected those plants with more pubescent seeds, thicker pericarps, and less rounded seeds. Seed pubescence and shape were shown to be heritable traits. Our findings provide insights into the understanding of the evolution of seed traits in fire-prone environments and demonstrate that human-made fires can be driving evolutionary changes in plant species from ecosystems where fires do not occur naturally.
火是影响全球生态系统的主要干扰因素。系统发育研究表明，种子持久性（抗火性）的进化与火的频率或严重程度有关。然而，由火介导的自然选择导致的特定种子特征的存在仍然是植物进化中的一个关键问题。我们从微观进化的角度评估了火在种子特征进化中的作用，研究系统是智利灌木丛中的一种本地野生植物，火是一种新的人为干扰因素。我们表明，人为火灾正在塑造种子特征的进化，如柔毛和形状。种子柔毛、形状和种皮厚度的种群间变异与火灾频率密切相关，在一个种群中，火灾选择了那些种子上有更多柔毛、种皮更厚、种子形状更不规则的植物。种子柔毛和形状是可遗传的特征。我们的研究结果提供了对易发生火灾环境中种子特征进化的理解，并表明人为火灾可能正在推动那些在自然火灾不常发生的生态系统中生存的植物物种发生进化变化。
