Isn't that circular logic? Because it exists, that proves that evolution is true?
Because it has evolved special skills unique to its environment proves that TToE is true.
But to some degree, TToE says "survivors survive." This is not circular logic -- it is a theory based on the observation on how so many different species under different circumstances physically change over time to adapt to their environment. Those that cannot adapt cease to exist (despite the example of Liberals, but this is over a LONG period of time).
Existence IS proof of TToE.