"Species" is an artificial distinction that human biologists use to make it easier to talk about what's going on. There is no objective distinction between species. The idea that the universe somehow permits evolution within a species but does not permit evolution from one species to another is nonsensical, on roughly the same level as thinking that it's possible to walk one mile but not possible to walk ten miles.

Indeed, the first problem starts already with just the title of that notorious book: On the origin of species. What exactly is a species? If we cannot etch a reasonable definition for that term in stone, then all statements that make use of that term are questionable, on that basis alone. Evolutionism then becomes a theory about things that we cannot define that evolve into other things that we cannot define ... How could that ever be science?

And another post that shows more clearly that you don't know much about what evolution is

Are you seriously attempting to discredit evolution as a science based on one word in the title of a single book?

You don't need a definition of "species" to understand or work with evolution.