already the necessity of various links between the DG types by morphological transitions.

From the $\Lambda$CDM cosmology the baryonic matter should settle within Dark Matter (DM) halos, which originally preferred to form low-mass subhalos and hierarchically accumulate to massive galaxies. If the baryonic matter would follow this bottom-up structure formation, the subhalos should also assemble their gas at first and by this also evolve with SF to become the oldest galactic objects in the universe. That this picture seems to be too naive is simply understandable by three major physical principles:

1\. The gas assembly timescale should behave as the free-fall timescale $\tff$, namely, dependent on the gas density as $\rg^{-1/2}$, because gas is accreted through gravitation. Whether this accretion leads to the same enhancement of SF in DGs as observed and theoretically expected [@kho09] is still a matter of debate (see also sect. 2). Because the virial temperature in the DG gravitational potential does not accomplish values above 10$^5$ K, on the one hand, cold accretion [@dek09] is not necessarily required as for massive halos.

2\. The SF timescale $\tSF$ is defined as M$_g/\Psi$ with $\Psi$ as the SFR that, on the other hand, in the self-regulated SF mode 