To investigate the effects of intraspecific competition on adaptive changes in dispersiveness, two types of long-term serial transfer experiments were performed using Escherichia coli in static cultures. One was designed to create a relatively high degree of exploitation competition for substrates among cells by transferring a bacterial population of small inoculation size with relatively frequent intervals, while the other was designed to create relatively high density-dependent mortality (i. e. resource deprivation and starvation before the next transfer) by using a larger inoculation size with less frequent intervals. While dispersiveness increased under both experimental treatments, measurements indicate that adaptation are not unique to the experimental treatments. These results suggest that competition in bacterial populations may be alleviated by the enhanced dispersiveness of highly competitive cells from densely populated areas.