Data from: The genetic basis of a rare flower color polymorphism in Mimulus lewisii provides insight to the evolutionary mutation spectrum

A long-standing question in evolutionary biology asks whether the genetic changes contributing to phenotypic evolution are predictable. Here, we identify a genetic change associated with segregating variation in flower color within a population of Mimulus lewisii. To determine whether these types of changes are predictable, we combined this information with data from other species to investigate whether the spectrum of mutations affecting flower color transitions differs based on the evolutionary time-scale since divergence. We used classic genetic techniques, along with gene expression and population genetic approaches, to identify the putative, loss-of-function mutation that generates rare, white flowers instead of the common, pink color in M. lewisii. We found that a frameshift mutation in an anthocyanin pathway gene is responsible for the white-flowered polymorphism found in this population of M. lewisii. Comparison of our results with data from other species reveals a broader spectrum of flower color mutations segregating within populations relative to those that fix between populations. These results suggest that the genetic basis of fixed differences in flower color may be predictable, but that for segregating variation is not.进化生物学领域长期存在一个核心科学问题：驱动表型进化的遗传改变是否具有可预测性。本研究在刘易斯猴花（Mimulus lewisii）的一个自然种群中，鉴定出与花颜色分离变异相关的遗传改变。为明确此类遗传改变是否具备可预测性，我们将该发现与其他物种的相关数据相结合，探究影响花颜色转变的突变谱是否因物种分化后的进化时间尺度不同而存在差异。我们结合经典遗传学技术、基因表达分析及种群遗传学研究方法，鉴定出在该种群中导致罕见白色花（而非常见粉色花）的推定功能丧失突变（loss-of-function mutation）。研究发现，花青素通路（anthocyanin pathway）基因中的一处移码突变（frameshift mutation）正是该刘易斯猴花种群中白花多态性的成因。将本研究结果与其他物种的数据进行对比后可见，相较于种群间固定的花颜色突变，种群内分离的花颜色突变谱更为宽泛。上述结果表明，花颜色固定差异的遗传基础或具备可预测性，但针对种群内分离变异的遗传基础则不具备可预测性。