I need an example
I have been discussing the origin of life and how evolution works with a coworker. She's a theist but accepts evolution in a general sense, more micro than macro. I explained to her how a horse-like animal could change into a zebra based on natural selection, or the famous peppered moth story. Those she believed. I then tried to stretch (no pun intended) the horse example into a giraffe, and she was reluctant to believe it because a giraffe is "too different" than a horse but eventually accepted my premise to advance the conversation.
My idea (and I think the widely accepted idea) is the "primordial ooze" or as Ben Stein has put it, "lightning striking a mud puddle" or most likely life started around the vents in the sea floor. Regardless, we all have a common ancestor. My friend claims that evolution happened, but not from one ancestor. She thinks if it was lighting striking a mud puddle, there were many puddles and many lightning strikes. If it was the vents, it happened many places. Each place would have evolved one type of animal (dogs, cats, whales, ... I don't know how many she's talking about).
I need an example of how one species can evolve into two different species. My friend accepts adaptation and even huge changes over long periods of time and through many generations, but thinks it will still be the same species. Help?