I've got a bit of headcanon that states that midi-chlorians are attracted to the Force and sustain themselves on the Force, and so beings which are Force sensitive can sustain larger colonies of midi-chlorians, but that the connection ends there.

My headcanon also includes the idea that Galactic culture and science has become stagnant (explaining why nothing seemed to advance in the 19 years between ROTS and ANH, or in the 15-odd years between TPM and ROTS, for that matter); therefore, kyttarocentric Jedi researchers from Core worlds began and ended their research at midi-chlorians thousands of years ago, thus marginalizing the status of non-cellular life forms and explaining why there don't seem to be any sentient rock monster Jedi or gaseous cloud-being Jedi populating the CGI ranks of the Order in the prequels.

But again, that's all headcanon that helps me sleep at night after arguing with PT-lovers, or rationalize stuff away when I write fan fiction. Usually, I forget that midi-chlorians are even a thing, BECAUSE they are so redundant and lack any sort of real impact on the story (and because the only way I'll watch the PT is in fanedit format where all mention of midi-chlorians have been removed).