The Tree Rats all lived very happily together in their trees. They mated during the fall, had enough food to survive. Until one day...
An earthquake came and split the area the Tree Rats were living! This forced each side of Tree rats to move far away into a different area.
Some of tThe Tree Rats ended up moving to a very dry and hot area. They could no longer mate in the fall due to the heat. The Tree Rats now mated in the winter when it was cooler and easier to function.
This is such a weird tree
The other Tree Rats moved toward the north where it was much colder. To survive mating season they starting mating in the summer. They also started to adapt and change color and shape based on their new environment. There were no longer as many trees near by.
Where all the trees at?
The two Tree Rats had adapted and changed so much physically and in mating that they could no longer breed again. They are now two different species separated by temporal isolation.