Variation in seasonal timing traits and life history along a latitudinal transect in Mimulus ringens

Seasonal timing traits are commonly under recurrent, spatially-variable selection, and are therefore predicted to exhibit clinal variation. Temperate perennial plants often require vernalization to prompt growth and reproduction; however, little is known about whether vernalization requirements change across the range of a broadly distributed species. We performed a critical vernalization duration study in Mimulus ringens, coupled with population genomic analysis. Plants from 8 populations spanning the latitudinal range were exposed to varying durations of 4°C vernalization between 0-56 days, and flowering response was assessed. RADSeq was also performed to generate 1,179 polymorphic SNPs, which were used to examine population structure. We found unexpected life history variation, with some populations lacking vernalization requirement. Population genomic analyses show that these life history variants are highly divergent from perennials, potentially revealing a cryptic species. For per...