Sympatric speciation can happen without complete geographic isolation between different populations. It was previously believed that most species formed in separate areas, but new studies show that species can evolve even when populations overlap. The focus is now on understanding how gene flow is reduced, rather than just looking at geographic range. While sympatric speciation is rare, it is possible, especially with strong disruptive selection or mating preferences. Speciation is a complex process involving genetics, environment, and geography, and not just about where populations are located.