Identical butterflies with different genetic background shed new light on evolution | Animals

The two species of butterflies are both from the Heliconius genus, commonly known as passion flower butterflies. The two species separated from each other 11 million years ago and have followed their own evolutionary path ever since. Yet they currently have the same red-yellow-black wing pattern, which deters birds from eating them.

So for the butterflies there is a clear evolutionary advantage to the pattern of their wings. “This phenomenon has been known for some time in evolutionary biology. Now we also wanted to check whether the underlying genetics are also the same,” says Professor of Evolutionary Biology Steven Van Belleghem. “That could teach us which genetic processes drive evolution and allow us to make predictions about the animals past and present.”

However, the results show that there are fewer genetic similarities than previously thought. “The results were a surprise,” says Van Belleghem. “We expected to find the same gene pool.”

There are three specific genes that provide the color pattern of the butterflies: one gene provides the red color, one gene for the yellow and the last one for the black shades. Those three genes in turn switch on a whole battery of new, different genes to produce the final pattern.

“This shows that the genetic path they have taken is flexible,” says Van Belleghem. “As if the two species have arrived at the same body after eleven million years, but under the hood a completely different engine drives the whole process.”

The researchers conclude that adapting appearance to the environment occurs regularly in nature, but that the evolution towards it is unpredictable and can occur through different genetic mechanisms.