The expansion velocity <i>u</i>_<i>i</i> and each strain’s selective advantage relative to the mCherry strain <i>s</i>_<i>iR</i> = <i>u</i>_<i>i</i>/<i>u</i>_<i>R</i> − 1 measured over the course of seven days for radii greater than <i>R</i>₀ (the radius where distinguishable domain walls formed) averaged over three independent experiments conducted on separate sets of agar plates.

was the fitness of each strain relative to mCherry in liquid culture with respect to their basal growth rates gi and gR. The radial expansion velocity fitness siR did not match the well-mixed liquid-culture fitness . However, every strain in liquid culture still grew faster than mCherry. Interestingly, the black strain grew faster than the eCFP and eYFP strains in liquid culture while on agar, the eCFP and eYFP strains expanded faster than the black strain. See the Materials and methods for additional information.