  Asteroseismology provides a new avenue for accurately measuring the masses of
evolved globular cluster (GC) stars through the detection of their solar-like
oscillations. We present the first detections of solar-like oscillations in 47
red giant branch (RGB) and early asymptotic giant branch (EAGB) stars in the
metal-poor GC M80; only the second ever with measured seismic masses. We
investigate two major areas of stellar evolution and GC science; the multiple
populations and stellar mass-loss. We detected a distinct bimodality in the
EAGB mass distribution. We showed that this is likely due to sub-population
membership. If confirmed, it would be the first direct measurement of a mass
difference between sub-populations. A mass difference was not detected between
the sub-populations in our RGB sample. We instead measured an average RGB mass
of $0.782\pm0.009~\msun$, which we interpret as the average between the
sub-populations. Differing mass-loss rates on the RGB has been proposed as the
second parameter that could explain the horizontal branch (HB) morphology
variations between GCs. We calculated an integrated RGB mass-loss separately
for each sub-population: $0.12\pm0.02~\msun$ (SP1) and $0.25\pm0.02~\msun$
(SP2). Thus, SP2 stars have greatly enhanced mass-loss on the RGB. Mass-loss is
thought to scale with metallicity, which we confirm by comparing our results to
a higher metallicity GC, M4. We also find that M80 stars have insignificant
mass-loss on the HB. This is different to M4, suggesting that there is a
metallicity and temperature dependence in the HB mass-loss. Finally, our study
shows the robustness of the $\Delta\nu$-independent mass scaling relation in
the low-metallicity (and low-surface gravity) regime.
