By: Nia Campbell, Chris Driscoll, Ethan Fultz, and Rachael McCabe (Stonehill College, BIO323 Evolution, Spring 2018)
Regressive evolution is the process where a trait is lost or becomes dysfunctional in a species over generations. This type of evolution is the opposite of constructive evolution, where a species evolves a new or more complex structure. Regressive evolution is a difficult method to use to classify species into evolutionary lineages because it often can only be identified by finding a genetic trace, such as a mutated or deleted gene in the species’s genome. In a paper published by Christopher A. Emerling in 2017, three traits found in relatives of snakes were examined in snakes for evidence of regressive evolution: presence of claw keratin, taste receptors, and light-associated genes.