  We present a study of the colors, structural properties, and star formation
histories for a sample of ~1600 dwarfs over look-back times of ~3 Gyr
(z=0.002-0.25). The sample consists of 401 distant dwarfs drawn from the Galaxy
Evolution from Morphologies and SEDs (GEMS) survey, which provides high
resolution Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)
images and accurate redshifts, and of 1291 dwarfs at 10-90 Mpc compiled from
the Sloan Digitized Sky Survey (SDSS). The sample is complete down to an
effective surface brightness of 22 mag arcsec^-2 in z and includes dwarfs with
M_g=-18.5 to -14 mag. Rest-frame luminosities in Johnson UBV and SDSS ugr
filters are provided by the COMBO-17 survey and structural parameters have been
determined by S\'ersic fits. We find that the GEMS dwarfs are bluer than the
SDSS dwarfs by ~0.13 mag in g-r, which is consistent with the color evolution
over ~2 Gyr of star formation histories involving moderate starbursts and long
periods of continuous star formation. The full color range of the samples
cannot be reproduced by single starbursts of different masses or long periods
of continuous star formation alone. Furthermore, an estimate of the mechanical
luminosities needed for the gas in the GEMS dwarfs to be completely removed
from the galaxies shows that a significant number of low luminosity dwarfs are
susceptible to such a complete gas loss, if they would experience a starburst.
On the other hand, a large fraction of more luminous dwarfs is likely to retain
their gas. We also estimate the star formation rates per unit area for the GEMS
dwarfs and find good agreement with the values for local dwarfs.
