FIGURE 6 - Bi-plots showing (a) predicted variation in genetic
composition from GF-X and (b) variation in untransformed
environmental conditions (each colored point is a climate grid cell
within a subset of the range of balsam poplar containing the sample
populations). Locations of the 42 populations within each of these
spaces are indicated by three letter population codes. The VT and IH
common gardens are indicated by a red dot and red triangle respectively.
Colors in (a) represent gradients in genetic turnover derived from
transformed environmental predictors; locations with similar colors are
expected to harbor populations with similar genetic composition. In (b),
color similarity corresponds to environmental similarity uninformed by
genetic patterns. Labeled vectors indicate the direction and magnitude
of gradients with greatest contribution (y=latitude, elev=elevation,
bio2=mean diurnal range, bio10/bio11=mean summer / winter temperature,
bio18/bio19=summer/winter precipitation). Genetic offsets are
approximately the Euclidean distance from each population to the common
gardens in (a), whereas climate transfer distances are approximately the
Euclidean distance from each population to the common gardens in (b),
though note that variation in higher dimensions is not shown.