Saturday, September 24, 2016

Carp undergo 'reverse evolution' to get their scales back

Common carp, known also by its scientific name Cyprinus carpo, are scaly fish. However, there was a small group of carp that were selectively bred with no scales. European monks bred these carp to make the fish easier to cut open and cook. Also known as mirror carp, the species was initially introduced to Madagascar for fish farming purposes.

A carp

A recent study by The Royal Society shows that the population of mirror carp has declined since their introduction to Madagascar in 1912. Those carp have since evolved into scaly fish. Even though they still possess the genetic mutation that would give them smooth sides, the fish have scales. The article refers to this process as "reverse evolution", but I believe it is more of an environmental adaption. Scaled carp have better fitness; they are more likely to survive due to the scales' protection from predators and parasites. Therefore, the carp quickly adapted to their environment by evolving scales on their bodies. 

The process of the carp recovering scales took approximately one-hundred years. In the larger scheme of evolution, this adaption happened very rapidly. The environment heavily forced carp to recover scales. I believe this is a great example of observing selection through environmental adaptions, even though the fish were initially bred to not have a certain trait. Through scenarios like the common carp being bred without scales and relocated, we are able to see how beneficial evolution occurs within species due to environmental pressures, regardless of genetic modification.


  1. I think this article did an excellent job of portraying how fast the evolution of the crap fish happened. One hundred really is no time in all to completely get rid of its scales and then gain them back. I wonder if scientists are better able to pin point the exact cause of the rapid reverse evolution.

  2. I found this topic very interesting because it points out that no matter how humans interfere with the carp's genetics and breed them to have no scales, the carp will still evolve scales to adapt in its environment. I never knew that a trait like this evolved in only a hundred years, considering the fact that evolution of a certain trait can even take millions of years to take place. I wonder what other species could have undergone reverse evolution.