It turns out humans aren’t the only ones checking out what their neighbors are doing when looking for ideas on how to make life easier. All species adapt and evolve in a variety of ways. In fact, convergent evolution is way more common than previously thought.
Simply put, convergent evolution is when unrelated, or very, very distantly related species from different families develop similar traits, mostly based on their environment.
For example, consider sharks and dolphins. Both have smooth skin and fins that slice through water for efficiency and speed when pursuing prey or evading predators. Although they look and act similarly, these two species aren’t even closely related. Scientists say the most recent shared relative dates back around 290 million years ago.
Sharks are a fish, with ancestors that have always inhabited water. Dolphins, on the other hand, come from a lineage that took to land for time, then returned to the waters and evolved into the dolphins and whales we see today. They have few bodily systems that function alike. Sharks use gills to filter oxygen from the water and lay eggs. Meanwhile, dolphins come to the surface for air and give birth to live young. Dolphins have a bone skeleton while sharks are made up of cartilage.
When considering a case like this, it means what essentially was a land animal, then adapted to life in the water, spawning convergent evolution that now makes them look similar to those who never left the marine environment. Therefore, the traits these animals share were not a result of inheritance from a common ancestor. These traits evolved separately.
The evolutionary concept itself isn’t new. Anyone who’s studied Darwin is likely familiar with divergent evolution, which is when a species evolves over time into similar species with slightly different and better adapted traits. Darwin’s famously-documented example is the finches, who evolved into different species, each better adapted for eating fruit, insects, leaves or grubs.
In contrast, convergent evolution results when distinctly different species become more similar. These trait similarities are seen around the globe with wildlife adapting to their shared environment. For example, in the sky, birds and bats both have wings, yet birds are considered reptiles while bats are mammals. They, in fact, have little else in common. Even though the wings themselves are structurally comparable, the shape is convergent.
Moving to the forest, many unrelated animals have evolved to be able to grasp branches. Panda bears are one example, developing the opposable thumb around 30 million years after primates. Convergent evolution can be seen through unrelated species in locations across the globe from each other too. Marsupials are a model for study, since they are indigenous to Australia and, to a lesser degree, South America. Yet several animals in Australia carry identical traits to unrelated and distant animals elsewhere.
In the states, we’re familiar with moles. Australia has a comparable marsupial mole that digs and lives similarly. Both species have poor eyesight, since they live underground, but huge claws for effective digging. There’s also a marsupial equivalent to mice.
Looking at the northern flying squirrel, native to North America, compared to the Australian sugar glider, one might think they’re related, but they’re not. However, they share a host of traits that serve them well in their separate, yet similar, environments. Both species are nocturnal, live in trees, have large eyes, thick fur and those wing-like membranes that allow them to glide from tree to tree. You could also throw flying lemurs into the comparison, with their separately-developed stretchy “wings,” yet lemurs fall into the scientific order of primates.
As the world changes, animal species change with it, often taking several generations. So as the planet warms or cools and ecosystems are altered for a variety of reasons, animals can, and do, practice convergent and divergent evolution to adapt.
Previously, scientists relied heavily on the physical features of animals for classification. That science is constantly being updated as new information is discovered.
Even in this modern era, we continue to recategorize species through advanced technology that identifies genetic data rather than anatomical information. Molecular studies are now definitively establishing genetic connections, as well as separating species that were previously grouped in the same family tree.
This type of grouping finds animals who look and act completely differently share more common genetically than those grouped by physical characteristics. For example, elephant shrews, aardvarks, elephants, golden moles and swimming manatees are all classified as Afrotheria and share a geographic location in Africa. Studying the actual genetic lineage of animals upends the previous science of who’s related to who.
As it pertains to this discussion, it means that those animals we thought were sharing traits due to genetics are actually examples of convergent evolution. They are, in fact, not related, but have simply acquired similar characteristics as a way to adapt.
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