  How can effective barotropic matter emerge from the interaction of
cosmological fluids in an isotropic and homogeneous cosmological model ?
  The dynamics of homogeneous and isotropic
Friedmann-Lema\^itre-Robertson-Walker universes is a natural special case of
generalized Lotka-Volterra systems where each of the universe's fluid
components can be seen as a competitive species in a predator-prey model.
(Jungle universe : arXiv:1306.1037)
  In addition to numerical simulations illustrating this behaviour among the
barotropic fluids filling the universe, we analytically pinpoint that effective
time-dependent barotropic indices can arise from a physical coupling between
those fluids whose dynamics could then look like that of another type of cosmic
fluid, such as a cosmological constant.
  Since the nature of dark energy is still unknown, this dynamical approach
could help understanding some of the properties of dark matter and dark energy
at large cosmological scales.
