  To date, most simulations of the chemistry in protoplanetary discs have used
1+1D or 2D axisymmetric $\alpha$-disc models to determine chemical compositions
within young systems. This assumption is inappropriate for non-axisymmetric,
gravitationally unstable discs, which may be a significant stage in early
protoplanetary disc evolution. Using 3D radiative hydrodynamics, we have
modelled the physical and chemical evolution of a 0.17 M$_{\odot}$
self-gravitating disc over a period of 2000 yr. The 0.8 M$_{\odot}$ central
protostar is likely to evolve into a solar-like star, and hence this Class 0 or
early Class I young stellar object may be analogous to our early Solar System.
Shocks driven by gravitational instabilities enhance the desorption rates,
which dominate the changes in gas-phase fractional abundances for most species.
We find that at the end of the simulation, a number of species distinctly trace
the spiral structure of our relatively low-mass disc, particularly CN. We
compare our simulation to that of a more massive disc, and conclude that mass
differences between gravitationally unstable discs may not have a strong impact
on the chemical composition. We find that over the duration of our simulation,
successive shock heating has a permanent effect on the abundances of HNO, CN
and NH$_3$, which may have significant implications for both simulations and
observations. We also find that HCO$^+$ may be a useful tracer of disc mass. We
conclude that gravitational instabilities induced in lower mass discs can
significantly, and permanently, affect the chemical evolution, and that
observations with high-resolution instruments such as ALMA offer a promising
means of characterising gravitational instabilities in protosolar discs.
