  Galaxy scaling relations provide insights into the processes that drive
galaxy evolution. The extension of these scaling relations into the dwarf
galaxy regime is of particular interest. This is because dwarf galaxies
represent a crucial stage in galaxy evolution, and understanding them could
also shed light on their role in reionising the early Universe. There is
currently no consensus on the processes that dominate the evolution of dwarfs.
In this work we constrain the atomic gas sequence (stellar mass vs. atomic gas
fraction) and mass-metallicity relation (stellar mass vs. gas phase
metallicity) from dwarf ($10^{6.5}$ $\textrm{M}_{\odot}$) to massive
($10^{11.5}$ $\textrm{M}_{\odot}$) galaxies in the local Universe. The combined
optical and 21-cm spectroscopic observations of the DESI and ALFALFA surveys
allow us to simultaneously constrain both scaling relations. We find a slope
change of the atomic gas sequence at a stellar mass of $\sim 10^{9}
~\textrm{M}_{\odot}$. We also find that the shape and scatter of the atomic gas
sequence and mass-metallicity relation are strongly linked for both dwarfs and
more massive galaxies. Consequently, the low mass slope change of the atomic
gas sequence is imprinted onto the mass-metallicity relation of dwarf galaxies.
The mass scale of the measured slope change is consistent with a predicted
escape velocity threshold below which low mass galaxies experience significant
supernova-driven gas loss, as well as with a reduction in cold gas accretion
onto more massive galaxies.
