HI gas in galaxies from z = 0 to z = 0.2

Probing the evolution of galaxies through the neutral hydrogen window has until recently been limited to studies of environmentally driven evolution in the local universe. Detailed imaging studies of galaxies in Virgo and volume limited surveys of clusters out to z = 0.08 show that ram pressure stripping is one of the mechanisms that drives galaxy evolution even at considerable distances from the dense cluster cores. Hydrodynamical simulations show that indeed the effects of the ICM are felt out to the virial radius due to the complex structure of the ICM. Westerbork and Arecibo have begun to observe galaxies at cosmologically interesting distances (z = 0.2). Soon the EVLA will be able to make a complete census of all H I emission in cones of 40'×40' probing an instantaneous velocity range from z = 0 to 0.53, with a resolution of a few arcsec. If prime focus feeds were to be installed at the EVLA those studies could easily be extended out to z = 1 in the coming decade, making the EVLA a prime pathfinder for H I studies with the SKA.