Speciation is not the process of a species evolving into a "different" species.
It is the process of a species evolving into one or more "sub-species".
So if a salamander population speciates, the "new" species will just be a new type of salamander.
All descendants of species X will forever stay on the same branch, in the same lineage, of species X. They will always be a sub-group of that species.
All cats, lions, tigers,... = felines.
All humans, chimps, gorilla's,... = apes
All dogs, wolves,... = canines
All felines, apes, canines,... = mammals
All mammals = tetrapoda
All tetrapoda = vertebrates
All vertebrates = eukaryotes
And so on.
You need to learn to wrap your head around what the "gradual" part of a "gradual process" means. It seems like you do not get how, in evolution, EVERY creature ever born was of the SAME species as its direct parents.
At no point in history did a member of species X give birth to a member of species Y. It doesn't work that way.
Let's move away from the whole evolution bit, because in my experience creationists have to much emotional objections to have a rational and objective discussion on the subject. Instead, let's just focus on the nature of a gradual process of introducing small changes every generation and having them accumulate and what that inevitably results in.
Let's look at the development of languages.
I hope you are aware that all Roman languages (like French, Portugese, Spanish, Italian) derive from Latin, right?
So, the ancestors of french, portugese, spanish and italian people didn't speak those languages. Instead, they all spoke latin.
Now, consider this: do you think that at some point in history, a latin speaking mother raised a spanish speaking child?
I'll go ahead and assume that when it comes to languages, you understand that generation after generation, small changes are introduced and accumulate in the language.
When you understand the graduallity of this process, you can think about biology in the same manner. The principles of the process are the exact same.
1. because populations evolve, not individuals
2. if multiple independent populations would evolve in the exact same way, evolution theory in its current form would be false
3. following your trail of thought, then in an evolutionary context, there should be just 1 species on the entire planet.
4. hilarious how you again expose how little you understand of the process of evolution.
It's rather easy, actually.
You have population A. For some reason, it splits in 2 or more populations. Various potential reasons for that (none of them out of the ordinary): part of the popluation migrates away; geological changes splits the population (for example, formation of a river that cuts right through the habitat of the population), etc.
Now, you have population A1 and A2. They are genetically isolated from one another. So they each are on their own evolutionary path from that point on. Over time, they will gradually diverge fruther and further from one another.
Have you never wondered how come that we can instantly tell someone's ancestral geographic location, simply by seeing his/her face?
White caucasians have ancestry in Europe.
Dark caucasians have ancestry in the Middle east.
Black people have ancestry in Africa.
Asian people have ancestry in Asia.
The fact that we can pinpoint geographic locations based on nothing but facial features, is a direct result of what I explained above about populations splitting and becoming genetically isolated from one another - making sure every "sub-population" continues on its own evolutionary path and starts diverging from the other sub-populations.
From this knowledge, we can again make some predictions concerning the geographic distribution of species. And once more, all these predictions check out. It explains why we only find kangaroo's in Australia, for example.