I'm not sure. From TOS onward, we no longer see any indication that the Vulcans, Tellarites, and Andorians had their own fleets, at least non-Earth style vessels. We know that the Vulcans had transport craft, but it generally doesn't seem to make much sense that each of these worlds would continue to build their own ships after the founding of the Federation. It makes more sense to have one singular Starfleet charged with exploration and defense of the various member worlds/systems.
Although it begs the question why, even though Vulcan ships were more advanced and powerful at the time of the Federation's founding (based on ENT), their ships weren't the basis for the Federation Starfleet. The only answer I can come up with is the hostility between the Vulcans and Andorians, who would both rather work with humans than each other.