GIS mapping
To assess whether population genetic structure corresponded to landscape or ecological factors, we used QGIS (QGIS Development Team 2019) to overlay Canadian canola spatial density and soil zone data (open.canada.ca) on maps depicting the survey locations and average genetic clustering output by Structure for the CFM population dataset. The canola overlay depicts crop inventory values reported by AAFC (averaged between 2009-2018) as rasters that indicate the level of expected canola spatial density at each geographic location; regions of green indicate high canola density and regions of pale yellow represent low density. Yearly canola inventory maps were not available, so we were unable to consider any impact of temporal changes in regional canola inventory on CFM population structure. The soil zone overlay depicts the approximate agricultural extent of the Canadian Prairies, and was used to define the northern boundary of the CFM survey (see survey methods above).
RESULTS