8 Fascinating Examples of Convergent Evolution

This is when unrelated species evolve to have functionally similar features.

Indian flying fox
Miha Pavlin / Getty Images

Convergent evolution is when unrelated species evolve to have functionally similar features, known as analogous structures. In other words, despite lacking common ancestors, they evolve similar characteristics to fit into a specific ecological niche.

This form of evolution is often discussed with divergent evolution, which occurs when one species diverges into new species by developing variations in traits in response to environment and lifestyle.

Many instances of convergent evolution make us curious about why and how species converge (or join) over time and develop certain abilities. Here, we take a look at some fascinating examples of this type of evolution.

Homologous vs. Analogous Structures

Homologous structures refer to two or more structures found in different species that originated from a common ancestor. Analogous structures, on the other hand, refer to structures in different species that are not from the same ancestor.

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Birds and Bats

Close-Up Of Bat Flying In Mid-Air
Bernd Wolter / EyeEm / Getty Images

All bats and birds "converged" on the ability of flight in response to environmental stimuli and biological goals. Rhe arm bones in both birds and bats are structurally the same and considered homologous. The wing shape, however, is what is convergent.

Bat wings are flaps of skin stretched between bones, whereas birds have layers of feathers extending along their arms. These differences mean they came from different ancestors, but ultimately evolved the same ability to fly.

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Flying Lemurs and Sugar Gliders

Colugo Flying Lemur
Colugo Flying Lemur,. Cede Prudente / Getty Images

Given their distinctive gliding capabilities, you would assume that flying lemurs and sugar gliders are closely related. Sugar gliders are marsupials and more closely related to kangaroos and koalas, whereas flying lemurs are "placental mammals" and actually closest to primates.

Their "wings", however, are analogous structures that evolved independently of one another. Both have also evolved key characteristics suitable for treetop (arboreal) living and large eyes for seeing better in the dark (nocturnal)—examples of convergent evolution allowing them to thrive within the same ecological niche.

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Dolphins and Sharks

Group of Atlantic spotted dolphins (Stenella frontalis), underwater view, Santa Cruz de Tenerife, Canary Islands, Spain
George Karbus Photography / Getty Images

Sharks and dolphins couldn't be more different. Dolphins are mammals, and sharks are fish. A dolphin's skeleton is made of bone, and a shark's skeleton is composed of just cartilage. While dolphins must come to the surface to breathe air, sharks use gills to extract oxygen from the water.

However, both sharks and dolphins adopted the same characteristics—streamlined bodies, dorsal and pectoral fins, and flippers—in order to swim fast and catch prey. Fins function much like hands, and while dolphins are distantly related to mammals with hands, sharks are not, thus their fins would have come from a very different genetic source.

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Snakes and Worm Lizards

Blind snake Blanus cinereus Close Up
jopstock / Getty Images

Worm lizards are, indeed, just legless lizards and not as close to snakes as they appear. In 2011, an approximately 45-million-year-old worm lizard fossil was found in Germany. It was concluded that the fossil lizard had arms and legs, which were lost over time as worm lizards adapted without them.

The report also mentioned that the fossil had a thick skull designed for burrowing, same as the worm lizards and "a far cry from the light, bendy skulls of snakes." It's believed that these ancient lizards adapted to a headfirst digging lifestyle before losing their legs and lengthening their bodies.

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Nepenthaceae and Sarraceniaceae

Nepenthes burkei tropical pitcher plant. They produce nectar in their leaves to catch insects.
derketta / Getty Images

The carnivorous pitcher plants Nepenthaceae and Sarraceniaceae both have pitfall traps, which lure insects in either with nectar, bright colors, or both. They source minerals like nitrogen and phosphorous from the animals they consume.

Despite both having these traps, Nepenthaceae and Sarraceniaceae are separate species with mostly just this feature in common. The Old World-based Nepenthes consist of tropical pitcher plants found in Madagascar, South Asia, and Australia; New World-based Sarraceniaceae are hardier pitcher plants found in North and South America. They are found across a broad range of habitats, always with poor soil conditions, from pine barrens to sandy coastal swamps.

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Marsupial Opossums and New World Monkeys

White-headed monkey with a fruit in Corcovado
David González Rebollo / Getty Images

New World monkeys consist of arboreal primates found in forest habitats. They have prehensile tails, which allow them to grasp objects and hang from trees. Marsupial opossums can also do this with their tails, except they're not primates. They're marsupials, which means their babies are raised in a pouch on the mother's belly, like a kangaroo. Opossums are also the only non-primate to have opposable big toes, giving it unique agility.

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Euphorbia and Astrophytum Succulents

Euphorbia obesa, Euphorbiaceae, South Africa
Euphorbia obesa. shihina / Getty Images

While Astrophytum is a genus of species of cacti, Euphorbia obesa is related to poinsettias more than it is cacti. Still, both have evolved to be able to conserve water in hot desert climates. The two often appear together in succulent gardens, with many of their caretakers unaware of the differences because, at first glance, they look so similar.

Both store water in swollen stems, grow spines, and come in a variety of shapes and sizes. But cactus spines grow from an "areole", or small cushiony dot that protrudes from the side of the plant; they can be removed easily and are in fact designed to embed themselves in passing animals or humans. Euphorbias, by contrast, push their spikes (or thorns) right out of the plant's sidewall; they're usually thick and appear to be part of the stem. Ripping them off would harm the plant.

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Echidnas and Hedgehogs

Up close photo of Australian Echidna's face
Byronsdad / Getty Images

Quills are considered modified hairs that were adapted to serve a biological purpose, such as defend against predators or improve senses. In both echidnas and hedgehogs, these quills are short and thick, making the species look the same at a glance. However, echidnas are "spiny anteaters" native to Australia, Tasmania, and New Guinea that like to burrow, whereas hedgehogs come from Europe, Asia, and Africa, and prefer to nest. Echidnas produce eggs that hatch, and hedgehogs give birth to litters of live young.

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View Article Sources
  1. "Cryptolacerta and the rise of the worm-lizards." National Geographic.

  2. "Pitcher Plant." Britannica.