  We study the redshift evolution of galaxy pair fractions and merger rates for
different types of galaxies using kinematic pairs selected from the DEEP2
Redshift Survey. By parameterizing the evolution of the pair fraction as
(1+z)^{m}, we find that the companion rate increases mildly with redshift with
m = 0.41+-0.20 for all galaxies with -21 < M_B^{e} < -19. Blue galaxies show
slightly faster evolution in the blue companion rate with m = 1.27+-0.35 while
red galaxies have had fewer red companions in the past as evidenced by the
negative slope m = -0.92+-0.59. We find that at low redshift the pair fraction
within the red sequence exceeds that of the blue cloud, indicating a higher
merger probability among red galaxies compared to that among the blue galaxies.
With further assumptions on the merger timescale and the fraction of pairs that
will merge, the galaxy major merger rates for 0.1 < z <1.2 are estimated to be
~10^{-3}h^{3}Mpc^{-3}Gyr^{-1} with a factor of 2 uncertainty. At z ~ 1.1, 68%
of mergers are wet, 8% of mergers are dry, and 24% of mergers are mixed,
compared to 31% wet mergers, 25% dry mergers, and 44% mixed mergers at z ~ 0.1.
The growth of dry merger rates with decreasing redshift is mainly due to the
increase in the co-moving number density of red galaxies over time. About 22%
to 54% of present-day L^{*} galaxies have experienced major mergers since z ~
1.2, depending on the definition of major mergers. Moreover, 24% of the red
galaxies at the present epoch have had dry mergers with luminosity ratios
between 1:4 and 4:1 since z ~ 1. Our results also suggest that the wet mergers
and/or mixed mergers may be partially responsible for producing red galaxies
with intermediate masses while a significant portion of massive red galaxies is
assembled through dry mergers at later times.
