  We try to understand the trends in the mass density slopes as a function of
galaxy properties. We use the results from the best Jeans Anisotropic Modelling
(JAM) of the integral-field stellar kinematics for near 6000 galaxies from the
MaNGA DynPop project, with stellar masses of $10^{9-12}\ {\rm M_{\odot}}$,
including both early-type and late-type galaxies. We use the mass-weighted
density slopes for the stellar $\overline{\gamma}_*$, dark
$\overline{\gamma}_{\rm DM}$, and total $\overline{\gamma}_{\rm T}$ mass from
the MaNGA DynPop project. The $\overline{\gamma}_{\rm T}$ approaches a constant
value of 2.2 for high $\sigma_{\rm e}$ galaxies, and flattens for
lg$(\sigma_{\rm e}/{\rm km\ s^{-1}})\lesssim2.3$, reaching 1.5 for
lg$(\sigma_{\rm e}/{\rm km\ s^{-1}})\approx1.8$. The total and stellar slopes
track each other tightly, with $\overline{\gamma}_{\rm
T}\approx\overline{\gamma}_*-0.174$ over the full $\sigma_{\rm e}$ range. This
confirms the dominance of stellar matter within $R_{\rm e}$. We also show that
there is no perfect conspiracy between baryonic and dark matter, as
$\overline{\gamma}_*$ and $\overline{\gamma}_{\rm DM}$ do not vary inversely
within the $\sigma_{\rm e}$ range. We find that the central galaxies from TNG50
and TNG100 simulations do not reproduce the observed galaxy mass distribution,
which we attribute to the overestimated dark matter fraction, possibly due to a
constant IMF and excessive adiabatic contraction effects in the simulations.
Finally, we present the stacked dark matter density profiles and show that they
are slightly steeper than the pure dark matter simulation prediction of
$\overline{\gamma}_{\rm DM}\approx1$, suggesting moderate adiabatic contraction
in the central region of galaxies. Our work demonstrate the power of stellar
dynamics modelling for probing the interaction between stellar and dark matter
and testing galaxy formation theories.
