Available evidence suggests that hypersporulation is not easily evolved in vitro. Maughan and coworkers attempted to evolve populations of a laboratory strain of B. subtilis with a hypersporulating phenotype by repeatedly heat-shocking cultures. While their efforts to enrich for hypersporulators failed, other studies revealed that asporogenous mutants evolved readily [60, 61] , confirming many early studies ( [62] and references therein). With the exception of the studies by Maughan et al., most ofthese investigators applied selections intended to inhibit sporulation rather than to enrich for strains with elevated sporulation rates. The 1013 lineage was never heat-shocked during its many transfers; thus the adaptations seen in this work are the result of balancing sporulation versus vegetative growth for prolonged periods on agar slants. However, because undomesticated isolates were observed to sporulate to 98-100% [60] , we cannot formally exclude the possibility that in vitro culture of the 1942 strain following its isolation for an unknown period by the University of Wisconsin might have selected for a hyposporulating variant. In this scenario, the H101Rand A98P mutations would represent suppressor mutations. We consider this possibility unlikely, given the phenotypic similarity of two environmental isolates in the UW collection (1942 and NRS-356). Furthermore, a progression toward darker pigmentation and greater hemolysisis evident in the ''military'' lineage ( Figure 2B ). These phenotypic changes are associated with the accumulation of additional mutations including a P145L substitution mutation in sigH, a positive regulator of sporulation [63, 64] and an A13P mutation in scoC, a negative regulator of sporulation [65] . Together, the strains analyzed in this study suggest strong selective pressures on the genes in the sporulation pathway, and more carefully controlled studies should be carried out to determine the dynamics of in vitro evolution and adaptation of spore-forming organisms, as has been done extensively in E. coli [66, 67, 68, 69, 70] .