  Understanding the evolution of the N/O ratio in the interstellar medium (ISM)
of galaxies is essential if we are to complete our picture of the chemical
evolution of galaxies at high redshift, since most observational calibrations
of O/H implicitly depend upon the intrinsic N/O ratio. The observed N/O ratio,
however, shows large scatter at low O/H, and is strongly dependent on galactic
environment. We show that several heretofore unexplained features of the N/O
distribution at low O/H can be explained by the N seen in metal-poor galaxies
being mostly primary nitrogen that is returned to the ISM via pre-supernova
winds from rapidly rotating massive stars ($M \gtrsim 10$ M$_\odot$, $v/v_{\rm
crit} \gtrsim 0.4$). This mechanism naturally produces the observed N/O plateau
at low O/H. We show that the large scatter in N/O at low O/H also arises
naturally from variations in star-formation efficiency. By contrast, models in
which the N and O come primarily from supernovae provide a very poor fit to the
observed abundance distribution. We propose that the peculiar abundance
patterns we observe at low O/H are a signature that dwarf galaxies retain
little of their SN ejecta, leaving them with abundance patterns typical of
winds.
