Landmark configuration and displacement vectors that distinguish groups of sculpins. Fourteen Landmarks were chosen to analyse variability in sculpin body shape (top). CVA was used to identify axes along which different groups can be discriminated based on the relative position of landmarks to a reference. The shape change captured by these axes can be visualized as relative displacement vectors for each landmark on a deformation grid. CV axis 1 separates invasive sculpins from all stream sculpins and axis 2 further separates two populations of stream sculpins. CV axis 3 captures the shape component that is unique to recent hybrids. While the deformation along CV axes 1 and 2 can be expressed in terms of inflation or compression of body parts, the hybrid specific shape change appears to be less balanced.