  The mass-metallicity relation shows that the galaxies with the lowest mass
have the lowest metallicities. As most dwarf galaxies are in group
environments, interaction effects such as tides could contribute to this trend.
We perform a series of smoothed particle hydrodynamics (SPH) simulations of
dwarf galaxies in external tidal fields to examine the effects of tides on
their metallicities and metallicity gradients. In our simulated galaxies,
gravitational instabilities drive gas inwards and produce centralized star
formation and a significant metallicity gradient. Strong tides can contribute
to these instabilities, but their primary effect is to strip the outer
low-metallicity gas, producing a truncated gas disk with a large metallicity.
This suggests that the role of tides on the mass-metallicity relation is to
move dwarf galaxies to higher metallicities.
