Since Charles Darwin proposed the Theory of Evolution in the 1800s, biologists have been trying to reorganize the family trees of organisms by examining and comparing the anatomy and structure of their bodies. However, advancements in genetic sequencing technology reveal that this morphology-based technique is misleading and that convergent evolution might be more common than they previously thought.
What is Convergent Evolution?
Convergent evolution refers to how distantly related organisms evolve analogous body forms as they adapt to similar environments. Although they do not have common ancestors, unrelated species evolve similar characteristics that match a particular ecological niche.
A team of scientists from the Milner Centre for Evolution at the University of Bath compared the morphology-based evolutionary trees of organisms with those based on molecular data. After mapping the evolutionary trees according to geographical location, it was found that animals that are organized according to molecular trees live more closely than those grouped according to morphological trees. The result suggests that experts should overturn centuries of biological studies where living things are classified based on appearance.
Biogeography, or the study of the geographical distribution patterns of plants and animals, has been an important source of evidence in Darwin's theory of evolution through natural selection. Surprisingly, it has not been considered a way of examining the accuracy of evolutionary trees.
According to lead author Dr. Jack Oyston, their study found strong statistical proof that molecular trees fit better across the tree of life of plants, reptiles, birds, and insects. He also believes that gene sequencing plays a significant role as a widespread pattern of testing different evolutionary trees.
On the other hand, Professor Matthew Wills from the University of Bath explains that molecular data allows biologists to realize that convergent evolution happens all the time. It gives new insight that the organisms once thought to be closely related turned out to be far apart on the evolutionary tree.
What Organisms Follow the Convergent Evolution?
Instances of convergent evolution stir up curiosity among biologists about why and how certain organisms join over time and develop specific abilities. Such convergence can be observed across various animal and plant classifications.
For example, bats and birds converged on their ability to fly to respond to environmental stimuli, having wing shape as the convergent feature. Since they have different ancestors, bats developed wings from flaps of their skin, while birds developed layers of feathers along their arms. However, they both ultimately developed the ability to fly.
Sharks and dolphins are other unrelated animals that show convergent evolution. They belong to different classes, and they also differ in terms of their bone composition and mode of breathing. However, these animals adopted the same characteristic of having streamlined bodies to help them swim fast and hunt prey more effectively.
In the plant kingdom, convergent evolution can be observed in the cactus Astrophytum and a relative of poinsettia called Euphorbia obesa. These plants differ in how they grow their spine, but they evolved in their ability to conserve water in hot deserts.
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