Environmental conditions of population origins and gardens
Our genotypes originated from a steep climatic gradient of temperature (mean annual temperature: 10-17oC), aridity (mean annual precipitation: 609mm-2,705mm), and continentality (temperature difference between hottest and coldest month: 14 – 26oC). When summarized via a Principle Components Analysis (PCA), the first major axis of variation amongst climate variables across sites (PC1) describes an axis of cold and wet sites to hot and dry sites (Figure 2A). The second axis of variation represents continentality, ranging from sites with consistently cold winters and high amounts of snowfall to sites that are generally warmer and do not experience as extreme lows (Figure 2A). In comparison to Clatskanie, Corvallis is hotter, drier, and has more continentality, meaning colder, wetter winters and hotter, dryer summers.
While these are the average site conditions, at the time of sampling, both Clatskanie and Corvallis experienced the lowest temperatures recorded for those dates over the past 38 years (Figure 2 B-E, solid line). Minimum temperatures ranged from -10oC to 0oC and maximum temperatures never reached higher than 3-5oC. This is a key detail as starch synthesis and degradation enzymes cease to perform under 3-5oC (Pollock & Lloyd, 1987), thus these short-term temperature drops may have influenced our measures (Figure 2 B-E).