Exploring the role of local adaptation in the response of Maianthemum canadense to climate warming

By the year 2100, it is projected that average global temperatures will increase by ~4C. Shifts in species distributions have been evidenced as a common response to climate warming across taxonomic groups with migration to higher latitudes and elevations in response to warming being common. Species responses to climate warming can be influenced by the local adaptations of their populations. I hypothesized that populations of M. canadense from warmer locations would respond negatively to warming, while populations from cooler sites would exhibit neutral or positive responses to warming. Maianthemum canadense is a species that is associated with cool, moist microsites across its distribution. To examine the role of local adaptation within the context of projected climate warming across a wide-ranging species in the Appalachian region, I grew Maianthemum canadense individuals in controlled-environment growth chambers that simulated current and future projected average growing season temperatures throughout the sampled range. The individuals were propagated from rhizomes collected from distinct naturally occurring populations of this species in Tennessee, Virginia, Pennsylvania, and New York. As such, populations from warmer locations may already be experiencing the high temperature range limit for this species. I used a two-way factorial design with temperature assigned to growth chambers as main plots and population as a split-plot factor within chambers. Findings suggest that M. canadense does not respond well to warming overall at the species level and that populations in warmer parts of the current range could be most negatively impacted by future climate warming. Since M. canadense is a common understory monocot herb with wide distribution throughout the Appalachian region, and as such, could represent the responses of similar species as a response to future warming.