Fig. 7

Strong-selection weak-mutation experiments on inaccessible sequences. A Strong selection for accessibility in head tissue on 1000 randomly selected non-peak sequences (non-peaks in both tissues) results in rapidly increasing accessibility in both head and testis tissues. B Using the same examples as in A, strong selection for accessibility in both tissues results in rapidly increasing accessibility in both tissues. C Using the same examples as in A, strong selection for accessibility in the head and inaccessibility in the testis results in head-specific accessibility; however, adaptation is slowed compared to A. D The proportion of mutations made to examples in A also made in C, revealing distinct mutational paths to accessibility in head tissue