ANGELINI, David R.*; JOCKUSCH, Elizabeth L.; University of Connecticut, Storrs; University of Connecticut, Storrs: Developmental mechanisms underlying divergent morphology in the antennae of Tribolium flour beetles (Coleoptera)

Describing the mechanisms through which animal morphology evolves is a fundamental goal of modern biology, unifying developmental and evolutionary disciplines. We have chosen to examine this issue in flour beetles of genus Tribolium (Coleoptera, Tenebrionidae). Tribolium includes 30 species, which have diverged within approximately the last 15 million years. Many of these species are significant pests of stored grain products, which has made T. castaneum a popular genetic system. Among the T. castaneum, T. confusum, and T. brevicornis species groups, the adult antennae differ in their structure and the number of segments organized into the distal �club� region. We have taken a comparative developmental genetic approach to analyze the roles of appendage-patterning genes in pupal antennal development in Tribolium. Insect appendage development is best understood in Drosophila (Cyclorrhapha) where adult limbs develop in a derived state, from imaginal discs during larval instars. In contrast, Tribolium appendages develop in the primitive insect state, from embryonic limb buds. Larval appendages are subsequently repatterned during metamorphosis: a process about which little is known. Using candidate genes from Drosophila, such as bric-a-brac, arista-less and others, as well as classical genetic mutations isolated in Tribolium, we have begun to characterize antennal patterning in T. castaneum. The complete genome sequence of T. castaneum has aided in the analysis in putative gene regulatory regions. Comparisons of gene expression and function have also been undertaken in congeners in order to explore differences in antenna developmental mechanisms and their potential influence on divergent morphologies.