Since there’s no biological reproduction (although this is contradicted by mentions of “baby” rahi) in the MU, evolution as we know it most likely wouldn’t occur.
This is the only Greg-quote relating to evolution that I found:
“On the Rahi evolution question – Rahi could “evolve” the same way Ultron evolves, by rebuilding. The only thing is Rahi would need someone else to rebuild them, it is doubtful most would have the ability to do it themselves (we have run across some intelligent Rahi who might be able to do it at some point).”
The crux of the theory is that they:
OP was referring to the wolfrat, which appeared a bionicle game. I don’t know if it’s existance is canon or not