The Greater Complexity of Drosophila Mutants as Compared to the Wild Type: Part-­type, Shape and Color Complexity Over Two Focal Levels

Abstract

The Zero Force Evolutionary Law predicts an increase in complexity at all levels of biological hierarchy unless there are constraints or selective forces opposing that increase. I present the first test of this universal tendency by evaluating the complexity of Drosophila melanogaster mutants, which represent organisms that arise in a context where selective forces are greatly reduced. Complexity gains and losses were measured with respect to part types, shape and color over two independent focal levels. My results show, significantly, that D. melanogaster mutants are more complex than the wild type. I also find that among mutants, those that are weakly constrained are more complex with respect to part types, shape and color. These findings are the first step in testing whether the Zero Force Evolutionary Law is true, and provide the impetus for a larger research program devoted to understanding increases in complexity as the default expectation.