Continuing our series of articles written by NUI Galway Biotechnology undergraduate ReelLife Science team members, Cariosa Switzer introduces the concept of Convergent Evolution:

Convergent evolution is one of the most interesting topics studied within the field of evolution. It occurs when completely diverse species develop similar traits, habits or appearances, despite living in habitats that can be separated by thousands of miles. Their habitats usually have comparable aspects, such as climates or vegetation or the existence of predators. Dry regions of South Africa have a wide selection of succulent plants, some of which look very similar to American cacti, as both have evolved to endure minimal water levels. An example of animals that are linked by convergent evolution is the Honey Possum, native to Australia, and species of butterfly found all around the world. Both have evolved a long tongue for taking nectar from flowers (see below).

Honey Possum. Photo credit www.valleyofthegiantsecopark.biz
Honey Possum. Photo credit http://www.valleyofthegiantsecopark.biz
Painted Lady. Photo credit  www.greeneyedmuse.wordpress.com
Painted Lady. Photo credit http://www.greeneyedmuse.wordpress.com

Echolocation is a type of biological sonar used by both dolphins and bats, and is a well-known example of convergent evolution. Although it may seem that bats and dolphins do not live in similar environments, in fact, they both live in areas where visibility is poor. For bats it is in dark caves and for dolphins it is murky waters. These animals use sounds to “see”, by emitting calls into their environment and listening to the echoes bouncing back from animals and objects nearby. From the strength and delay in hearing the echo they are able to determine how close they are to these objects.

Echolocation. Image credit www.hearinghealthmatters.org/
Echolocation. Image credit http://www.hearinghealthmatters.org/

Scientists from Queen Mary University of London studied whether bats and dolphins had genetic similarities (i.e. a similar “genotype”) as well as being physically alike (i.e. a similar “phenotype”). In their paper, which was published by the scientific journal Nature, they describe how they looked at the genomes (collection of an organism’s genes) of 22 mammals including bottlenose dolphins, bats that echolocate, bats that don’t echolocate, humans, horses, dogs and mice. This study has been the largest search for evidence for genetic convergence ever undertaken.

Through this research, the team of scientists were able to prove that there is evidence of convergent evolution in nearly 200 different areas of the genome. This is a huge amount, as one of the leading biologists in this research, Joe Parker indicated – “A few dozen would probably have surprised us”.

This discovery is proving fundamental to our knowledge of convergent evolution, as it was previously assumed that the similarities were mainly physical, however, now, a whole new door has been opened in the study of convergent evolution.

If you want to see for yourself how bats use echolocation why not try out this game?

Cariosa Switzer

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