Dissertation Research: Imaginal Disc Development, Morphological Integration and Phylogenetic Pattern in Diopsid Dipterans

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9423436 WAGNER The primary goal of this research program is to examine the relationship between the genetic structure of species and the pattern of morphological evolution within the fly genus Diasemopsis. These flies are distinct because of the extreme elongation of the head into long eye-stalks. This bizarre morphological transformation may have led to changes in other morphological traits as a result of shared genetic effects between traits. Because any given gene may influence a number of different morphological traits, selection to change one part of an organism may have a cascade of effects on other body parts. Presently, it is unknown how much this genetic connection between body parts directs the course of evolution since it is possible this connection can be broken over time. The first step toward answering this question requires comparing the types of genetic connections between different species. If different species show similar genetic structure (i.e. different body parts are linked genetically in the same manner in both species), this could profoundly influence the course of evolution. This research will examine this possibility in two different species of stalk-eyed flies. In addition, the pattern of shared genetic effects between traits will be compared with the pattern of morphological evolution within these flies to determine if those genetic connections which have remained fixed between species have constrained the divergence of these species.