Department of Ecology and Evolution and Consortium for Inter-Disciplinary Environmental Research, Stony Brook University, Stony Brook, NY, 11794, USA.
Department of Biological Sciences, California State University, Sacramento, CA, 95819, USA.
Heredity (Edinb). 2019 Apr;122(4):417-427. doi: 10.1038/s41437-018-0129-3. Epub 2018 Aug 17.
Determining the processes responsible for phenotypic variation is one of the central tasks of evolutionary biology. While the importance of acoustic traits for foraging and communication in echolocating mammals suggests adaptation, the seldom-tested null hypothesis to explain trait divergence is genetic drift. Here we derive F values from multi-locus coalescent isolation-with-migration models, and couple them with estimates of quantitative trait divergence, or P, to test drift as the evolutionary process responsible for phenotypic divergence in island populations of the Pteronotus parnellii species complex. Compared to traditional comparisons of P to F, the migration-based estimates of F are unidirectional instead of bidirectional, simultaneously integrate variation among loci and individuals, and posterior densities of P and F can be compared directly. We found the evolution of higher call frequencies is inconsistent with genetic drift for the Hispaniolan population, despite many generations of isolation from its Puerto Rican counterpart. While the Hispaniolan population displays dimorphism in call frequencies, the higher frequency of the females is incompatible with sexual selection. Instead, cultural drift toward higher frequencies among Hispaniolan females might explain the divergence. By integrating Bayesian coalescent and trait analyses, this study demonstrates a powerful approach to testing genetic drift as the default evolutionary mechanism of trait differentiation between populations.
确定导致表型变异的过程是进化生物学的核心任务之一。虽然在回声定位哺乳动物中，声音特征对于觅食和交流很重要，这表明它们是适应的结果，但很少被测试的解释特征分歧的零假设是遗传漂变。在这里，我们从多基因座 coalescent 隔离-迁移模型中得出 F 值，并将其与数量性状分歧的估计值 P 耦合，以检验漂变是否是导致 Pteronotus parnellii 物种复合体岛屿种群表型分歧的进化过程。与传统的 P 与 F 的比较相比，基于迁移的 F 估计值是单向的而不是双向的，同时整合了基因座和个体之间的变异，并且可以直接比较 P 和 F 的后验密度。我们发现，尽管与波多黎各的种群已经隔离了许多代，但较高叫声频率的进化与遗传漂变不一致。尽管伊斯帕尼奥拉种群的叫声频率存在二态性，但雌性的较高频率与性选择不兼容。相反，伊斯帕尼奥拉雌性之间向更高频率的文化漂变可能解释了这种分歧。通过整合贝叶斯 coalescent 和性状分析，本研究证明了一种强大的方法，用于检验遗传漂变是否是种群间性状分化的默认进化机制。
