The idea “a true tree of life” in terms of “species” is inconsistent, actually paradoxically contradictory, by resting of the fundamental assumption that kinds are real (as Russell’s paradox demonstrates).
It means that “a true tree of life” actually is a paradox, ie, a paradoxical contradiction, like whether the barber in the barber’s paradox shaves himself or not – if he does, then he doesn’t, and if he doesn’t, then he does. The idea tilt between two contradictory states.
“A true tree of life” is thus not something that can be found, but just a mental construct, like “God(s)” and “Higgs particle”. None of them can exist in this world, because nothing can both be and not be at the same time. If something could, then this thing would transgress the boundary between reality and dream, and thus also the boundary between is and was, meaning that it would wipe out the difference that the distinction of itself rests on, and thus also itself. It would thus eradicate itself in the moment it comes into existence.
This is the world of contradictions like “a true tree of life”, “God(s)” and “Higgs particle” – an impossibility. They are interesting ideas, but impossible. If rational people do not agree on this, then rationality itself is endangered.
This does not mean that the idea of the biological diversity having originated by evolution is inconsistent, but just that describing this process with “a true tree of life” is. The problem for rationalists is thus to find a rational (consistent) model for this process. The fundamental problem for this search is, however, that it, itself, is exposed to the process of evolution.