Isopleiotropy and Allopleiotropy

And now for a rare science post. My laboratory studies genetic correlations between traits. Such correlations can be caused by pleiotropic genes, which are genes that affect more than one phenotype. Recently, I thought of classifying these pleiotropies into two different types. If the two traits are very similar, or essentially the same trait, such that you would expect them to utilize essentially the same set or a very similar set of genes, just at different times and places during development, then these traits are hereby be defined as isopleiotropic. On the other hand, if the traits are quite different and would not be expected to involve the same genes (but nevertheless they do), then these traits are hereby be defined allopleiotropic.

An example of isopleiotropic traits would be legs on different segments of an arthropod or eye spots on different parts of a butterfly wing. An example of allopleiotropic traits would be pigmentation and phototactic behavior in Drosophila, both of which are known to require tan, ebony, and several other genes.