  In this work we derive analytical relations between Entanglement and
Coherence as well as between Discord and Coherence, for Bell-diagonal states
and for X states, evolving under the action of several noise channels: Bit
Flip, Phase Damping and Depolarizing. We demonstrate that for these families,
Coherence is the fundamental correlation, that is: Coherence is necessary for
the presence of Entanglement and Discord.
