Galaxy and Mass Assembly (GAMA): Formation and Growth of Elliptical
  Galaxies in the Group Environment
  There are many proposed mechanisms driving the morphological transformation
of disk galaxies to elliptical galaxies. In this paper, we determine if the
observed transformation in low mass groups can be explained by the merger
histories of galaxies. We measured the group mass-morphology relation for
groups from the Galaxy and Mass Assembly group catalogue with masses from
10$^{11}$ - 10$^{15}$ M$_{\odot}$. Contrary to previous studies, the fraction
of elliptical galaxies in our more complete group sample increases
significantly with group mass across the full range of group mass. The
elliptical fraction increases at a rate of 0.163$\pm$0.012 per dex of group
mass for groups more massive than 10$^{12.5}$ M$_{\odot}$. If we allow for
uncertainties in the observed group masses, our results are consistent with a
continuous increase in elliptical fraction from group masses as low as
10$^{11}$M$_{\odot}$. We tested if this observed relation is consistent with
merger activity using a GADGET-2 dark matter simulation of the galaxy groups.
We specified that a simulated galaxy would be transformed to an elliptical
morphology either if it experienced a major merger or if its cumulative mass
gained from minor mergers exceeded 30 per cent of its final mass. We then
calculated a group mass-morphology relation for the simulations. The position
and slope of the simulated relation were consistent with the observational
relation, with a gradient of 0.184$\pm$0.010 per dex of group mass. These
results demonstrate a strong correlation between the frequency of merger events
and disk-to-elliptical galaxy transformation in galaxy group environments.
