Convergent evolution is the process by which two species develop similar features despite not sharing a recent common ancestor. Evolutionary biologists explain these similar characteristics as the product of natural selection. By sharing similar ecological niches, the two unrelated species benefit from developing the same functional characteristics.

Convergent evolution occurs in all biological kingdoms, and it is particularly noticeable in plant species and animal species. The only requirement is that two species, lacking a common ancestor, undergo independent evolution that results in similar body forms or similar useful traits.

To observe convergent evolution in nature, evolutionary biologists seek out different organisms that show independent evolution of similar features, similar structures, or similar traits.

1. Marine animals: Fish and dolphins are vastly different animals with different underlying DNA sequences and nervous systems. Yet because they inhabit similar environmental conditions, they have developed analogous structures. The fin of a fish and the fin of a dolphin serve a common purpose, but they evolved quite differently. Dolphins, which are placental mammals, have a fin that is closely related to the human hand. Fish have no close relatives with hands, so their fins come from a very different source on a genetic level.

2. Flying animals: Birds, bats, and insects all developed wings via different evolutionary paths. For example, hummingbird hawk moths (a type of insect) strongly resemble hummingbirds and have wings that allow them to hover while collecting nectar from flowers. While both species are distinct, their wings shapes converged on a similar evolutionary trajectory.

3. Plants: In the plant kingdom, many species exhibit convergent traits when it comes to their fruit. Many plants rely on their fruit for reproduction, as it attracts animals who eat the fruit and spread its seeds. In order to compete for animals’ appetites, many plant species have undergone evolutionary change whereby fruit gets bigger and fleshier. These similar adaptations from unrelated plants allow them to survive the selective pressures they experience in similar niches.

In many ways, divergent evolution is the opposite of convergent evolution. Whereas convergent evolution involves unrelated species that develop similar characteristics over time, divergent evolution involves species with a common ancestor that change to become increasingly different over time.

• Divergent evolution: Divergent evolution occurs when two organisms with a common ancestor end up as different species. For instance, bats and mice share a recent common ancestor, but divergent evolution has turned them into two entirely different species. Bat wings are equivalent to the front paws of mice, yet they have spread apart and developed a fleshy webbing. Bat wings and mouse paws are homologous structures: body parts that share a common origin but no longer serve the same purpose.
• Convergent evolution: Convergent evolution occurs when two organisms that lack a recent common ancestor end up more and more alike as they adapt to a similar ecological niche. The organisms have convergent phenotypes, and their similar structural forms are called analogous structures (such as bird wings and bat wings).