  A $U(1)$ gauge theory coupled to a Wilson fermion on a $2+1$ dimensional
cubic lattice is known to exhibit Chern insulator like topological transitions
as a function of the the ratio $M/R$ where $M$ is the fermion mass and $R$ is
the Wilson parameter. I show that, with $M$ and $R$ held fixed, a rectangular
lattice with anisotropic lattice spacing can exhibit distinct topological
phases as a function of the lattice anisotropy. As a consequence, a $2+1$
dimensional lattice theory without any domain wall in the fermion mass can
still exhibit chiral edge modes on a $1+1$ dimensional defect across which
lattice spacing changes abruptly. Likewise, a domain wall in the fermion mass
on a uniform rectangular lattice can exhibit discrete changes in the number and
chirality of zero modes as a function of lattice anisotropy. The construction
presented in this paper can be generalized to higher dimensional space-time
lattices.
