Predicting the strength of urban-rural clines in a Mendelian polymorphism along a latitudinal gradient

Cities are emerging as models for addressing the fundamental question of whether populations evolve in parallel to similar

environments. Here, we examine the environmental factors that drive the evolution of parallel urban-rural clines in a Mendelian

trait—the cyanogenic antiherbivore defense of white clover (Trifolium repens). Previous work suggested urban-rural gradients in

frost and snow depth could drive the evolution of reduced hydrogen cyanide (HCN) frequencies in urban populations. Here, we

sampled over 700 urban and rural clover populations across 16 cities along a latitudinal transect in eastern North America. In each

population, we quantified changes in the frequency of genotypes that produce HCN, and in a subset of the cities we estimated

the frequency of the alleles at the two genes (CYP79D15 and Li) that epistatically interact to produce HCN. We then tested the

hypothesis that cold climatic conditions are necessary for the evolution of cyanogenesis clin...

城市正逐渐成为解答「群体是否会在相似环境中发生平行演化」这一基础科学问题的理想模型。本研究聚焦于驱动孟德尔性状（Mendelian trait）呈现城乡平行渐变群演化的环境因素——白车轴草（Trifolium repens）的产氰型抗草食动物防御机制。
既往研究表明，霜冻与积雪深度的城乡梯度，可能推动城市种群中氰化氢（hydrogen cyanide, HCN）频率降低的演化过程。
本研究沿北美东部的纬度样带，在16座城市中采集了超过700个城乡车轴草种群样本。在每个种群中，我们定量分析了产氰基因型的频率变化；同时在部分城市的种群中，我们估算了两个上位互作产氰的基因（CYP79D15与Li）的等位基因频率。
随后我们验证了「寒冷气候条件是氰化渐变群演化的必要条件」这一假说。