If, as "creation science" teaches, every species got whomped into existence in a couple of days, with no pattern of gradual speciation, then what kind of "tree" would you assemble? You could group things by size, by color, or by any other characteristic you wanted. Or you could just make an alphabetical list. It wouldn't matter, because each is an isolated, stand-alone act of creation. The theory of evolution, however, dictates exactly what kind of pattern must exist, just as your own geneological chart must have a pattern. That is a powerful and precise prediction.
And -- surprise, surprise! -- when a Darwinian tree is assembled, we find that the genetic composition of the various species reveals exactly what one would expect if the later species were indeed descended from those earlier on the tree. Do you suppose that's just a wild coincidence?