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).