School of Biological Sciences, Washington State University, Pullman, Washington 99164, USA.
Evolution. 2011 May;65(5):1511-3. doi: 10.1111/j.1558-5646.2011.01224.x. Epub 2011 Jan 27.
Baker's Law states that selfing should commonly be selected during dispersal because bottlenecks during colonization limit the availability of mates. Although this truism has broad intuitive appeal, a recent body of theory (Cheptou and Massol 2009; Massol and Cheptou 2011) casts doubt on whether adaptation favors both selfing and dispersal when both parameters are free to evolve. In these models, the joint evolution of dispersal and the selfing rate are considered in a metapopulation, with a spatially and temporally variable pollination environment. Under these conditions, adaptation favors one of two strategies: the "dispersal/outcrosser" syndrome and the "no dispersal/selfing" syndrome. These results appear to contradict the prediction of Baker's Law. These models clarify how variation in the pollination environment per se cannot generate an association between selfing and dispersal. That being said, demographic factors during dispersal episodes are likely to be important in generating patterns consistent with Baker's law. Determining whether Baker's law maintains its predictive utility requires determining whether seed banks, the perennial habit, multiple introductions, or the simultaneous arrival of many founders weaken selection for selfing during the bottleneck associated with a dispersal event. These issues highlight the many assumptions that are necessary for Baker's law to hold.
贝克法则指出，在扩散过程中，自交通常会被选择，因为在殖民过程中的瓶颈限制了配偶的可用性。尽管这一真理具有广泛的直观吸引力，但最近的一系列理论（Cheptou 和 Massol 2009；Massol 和 Cheptou 2011）质疑当两个参数都可以自由进化时，适应是否同时有利于自交和扩散。在这些模型中，扩散和自交率的联合进化在具有空间和时间变化的授粉环境的集合种群中进行考虑。在这些条件下，适应有利于两种策略之一：“扩散/异交者”综合征和“不扩散/自交者”综合征。这些结果似乎与贝克法则的预测相矛盾。这些模型阐明了授粉环境本身的变化如何不能产生自交和扩散之间的关联。也就是说，在扩散过程中出现的人口统计学因素可能在产生与贝克法则一致的模式方面非常重要。确定贝克法则是否保持其预测效用需要确定种子库、多年生习性、多次引入或许多创始人同时到达是否会削弱与扩散事件相关的瓶颈期间自交的选择。这些问题突出了贝克法则成立所必需的许多假设。
