  We derive the number of dynamically close companions per galaxy ($N_c$) and
their total luminosity ($L_c$) for galaxies in the Millennium Galaxy Catalogue:
$N_c$ is similar to the fraction of galaxies in close pairs and is directly
related to the galaxy merger rate. We find $N_c=0.0174 \pm 0.0015$ and
$L_c=(252 \pm 30) \times 10^6$ $L_{\odot}$ for galaxies with $-22 < M_B -5 \log
h < -19$ with $<z>=0.123$ and $N_c=0.0357 \pm 0.0027$, $L_c= (294 \pm 31)
\times 10^6 L_{\odot}$ for galaxies with $-21 < M_B -5 \log h < -18$, with
$<z>=0.116$. The integrated merger rate to $z=1$ for both samples is about 20
%, but this depends sensitively on the fraction of kinematic pairs that are
truly undergoing a merger (assumed here to be 50%), the evolution of the merger
rate (here as $(1+z)^3$) and the adopted timescale for mergers (0.2 and 0.5 Gyr
for each sample, respectively). Galaxies involved in mergers tend to be
marginally bluer than non-interacting galaxies and show an excess of both
early-type and very late-type objects and a deficiency of intermediate-type
spirals. This suggests that interactions and mergers partly drive the star
formation and morphological evolution of galaxies.
