  We discuss the role of environmental mechanisms in the evolution of dwarf
galaxy satellites using high-resolution N-Body+SPH simulations that include
simultaneously tidal forces, ram pressure and heating from ionizing radiation
fields. Tidally induced bar-buckling instabilities can transform a rotating
disky dwarf into a pressure supported spheroidal. Efficient gas removal
requires instead a combination of tidal mass loss and ram pressure stripping in
a diffuse gaseous corona around the primary system. The efficiency of ram
pressure depends strongly on how extended the gas remains during the evolution.
Bar driven inflows that tend to drive the gas to the bottom of the potential
well can be opposed by the heating from ultraviolet radiation. We show that
even fairly massive dwarfs ($V_{peak} >$ 30 km/s) would be stripped of their
gas over a few Gyr if they enter the Milky Way halo at $z > 2$ thanks to the
effect of the cosmic UV background. Gas mass loss can be much faster, occurring
in less than 1 Gyr, if dwarf satellites have their first close approach with
the primary at the epoch of bulge formation. Indeed at that time the primary
galaxy should have a FUV luminosity comparable to that of major present-day
starbursts, resulting in a local radiation field even more intense than the
cosmic background.
