An example of convergent evolution is the similar overall body structure of sharks and dolphins. The shark is a fish while the dolphin is a mammal, but their bodies have evolved to become similar. Another example is the adaptations for gliding found in both sugar gliders and flying squirrels.
While sharks and dolphins have no close family relationship in the evolutionary tree, they live in similar environments. Natural selection causes each of these species to evolve similarly. They need fins for swimming and a long sleek body to move through the water, yet sharks receive their oxygen through gills while dolphins must surface to breathe.
Sugar gliders are native to Australia, while flying squirrels are from the United States. Both animals have similar rodent bodies and skin attached between their body and forearm, allowing them to glide from trees. These two animals live in similar environments and their evolution allows them to survive using similar mechanisms.
Convergent evolution is not limited to the animal kingdom. Desert plants often evolve to develop water-holding chambers for survival in the arid region. While the plants of the American and African deserts are not closely related, they have similar evolutionary traits that have developed from separate branches of the evolutionary tree.