  We fit the ultrahigh-energy cosmic-ray (UHECR, $E\gtrsim0.1$ EeV) spectrum
and composition data from the Pierre Auger Observatory at energies
$E\gtrsim5\cdot10^{18}$ eV, i.e., beyond the ankle using two populations of
astrophysical sources. One population, accelerating dominantly protons ($^1$H),
extends up to the highest observed energies with maximum energy close to the
GZK cutoff and injection spectral index near the Fermi acceleration model;
while another population accelerates light-to-heavy nuclei ($^4$He, $^{14}$N,
$^{28}$Si, $^{56}$Fe) with a relatively low rigidity cutoff and hard injection
spectrum. A significant improvement in the combined fit is noted as we go from
a one-population to two-population model. For the latter, we constrain the
maximum allowed proton fraction at the highest-energy bin within 3.5$\sigma$
statistical significance. In the single-population model, low-luminosity
gamma-ray bursts turn out to match the best-fit evolution parameter. In the
two-population model, the active galactic nuclei is consistent with the
best-fit redshift evolution parameter of the pure proton-emitting sources,
while the tidal disruption events could be responsible for emitting heavier
nuclei. We also compute expected cosmogenic neutrino flux in such a hybrid
source population scenario and discuss possibilities to detect these neutrinos
by upcoming detectors to shed light on the sources of UHECRs.
