Anthropogenic climate change has already influenced the ecological dynamics of species, through altitudinal and latitudinal shifts in geographic ranges, altered phenology, and disrupted species interactions. Owing to the rapid pace of climate change, species might not have the dispersal abilities needed to track preferred climates, nor the traits necessary to survive in novel conditions. Climate change will likely impose considerable selection for stress tolerance. Nevertheless, the microevolutionary consequences of contemporary climate change remain essentially unresolved. We are investigating constraints on adaptation in the context of global change using a species of mustard (Boechera stricta) native to the U.S. Rocky Mountains. My postdoc advisor, Tom Mitchell-Olds, our colleages, and I have detected quantitative trait loci (QTL) that influence local adaptation in B. stricta to contrasting field environments at different latitudes (38.7 ˚N vs. 45.7 ˚N; Anderson et al., 2012) and have documented long-term acceleration in flowering phenology driven by climate change (Anderson et. al., 2012. PRSB). Boechera stricta primarily self-pollinates and generally disperses seeds only short distances, suggesting that this species has restricted migratory potential. Our ongoing studies in this system attempt to disentangle the relative contributions of phenotypic plasticity, migration and adaptive evolution to B. stricta’s response to climate change. In early October 2013, the Anderson lab installed a field experiment to examine evolution in the context of climate change in subalpine meadows near the Rocky Mountain Biological Lab in Gothic, Colorado. We planted ~8200 rosette B. stricta and ~8700 seeds from 110 genotypes into five experimental gardens (elevations of gardens: 2530 m, 2710 m, 2884 m, 3130 m, and 3340 m). We will expose half of the individuals to contemporary climates. The other half of the plants will experience early snowmelt, reduced snowpack, and elevated growing season temperatures, reflecting climate projections for the mid-21st Century. This experiment will allow us to examine how climate influences patterns of trait expression, natural selection, and local adaptation. We will also test whether phenotypic plasticity could enable population persistence in the short term and whether fluctuating conditions associated with climate change actually favor plasticity. Finally, we will evaluate whether local populations maintain sufficient genetic variation to respond to novel selection. In this photo, Bashira is tending to recent transplants at the highest elevation garden (3340 m). We marked the southwest corner of each 2 m by 1 m block with a fence post, which will allow us to locate plots when the snow recedes to 1 m in depth. At that point (April or May 2014), we will remove snow from the future climate plots (red and green posts), but not the contemporary climate plots (white and green posts). We will then passively warm the future climate plots using louvered open-sided chambers.
