Figure 1. Seasonal drought timing varies across the Arabidopsis species range.

(A) Examples of home environments for two well-studied Arabidopsis ecotypes (Mojica et al., 2016) from Italy and Sweden, left and right plots respectively, showing historical drought conditions detected using the VHI and (B) drought frequency (VHI <40, NOAA drought classification) by week (line) and season (bars). Arrows mark locally observed flowering dates (Mojica et al., 2016) and gray bars highlight the typical reproductive growing season used to quantify a drought-timing index. (C) Variation in historical drought timing experienced at the home environments of Arabidopsis ecotypes across the species range (figure supplement). Large values indicate environments where spring droughts occur more frequently than summer drought (i.e. where the frequency of drought decreases over the course of the typical reproductive growing season) and vice versa.

Figure 1—figure supplement 1. Arabidopsis ecotypes are distributed across satellite-detected drought timing gradients.

Historical patterns in drought conditions were calculated from the Vegetative Health Index (VHI, Figure 1A) and converted into a drought-timing index (Figure 1B and C). Large values of this index indicate environments where spring droughts occur more frequently than summer drought (i.e. where the frequency of drought decreases over the course of the reproductive growing season) and vice versa (seasonal drought frequency map data available at greymonroe.github.io/data).