Our experimental design (Fig. 1A) involved propagating C.
reinhardtii cells through vegetative growth in batch cultures on a
regime of 1:100 serial transfers. Adaptation in these evolved light
(EL) cells was implied by an increase in growth rate when
compared to the progenitor (PL) cells (Fig. 1B). After 1,880
generations (283 serial transfers), one culture (evolved light; EL)
was chosen for genome analysis. This population had a growth
rate that was ca. 35% greater than the PL population, a result that
was validated by a comparison of PL and EL growth curves in
triplicate cultures (Fig. 1C). Analysis of cell size showed
surprisingly that in exponential phase PL (5.2761.21 mm [standard
deviation]) and EL (5.1361.18 mm) cells were the same size
despite clear differences in the growth rate. However, during
stationary phase the EL cells were ca. 1 mm smaller in diameter
(4.6561.17 mm vs. 5.6761.20 mm; Fig. 2). When acetate was
removed from the culture medium, the PL and EL cells had
significantly lower but equal growth rates (Fig. 1C).