Meeting Abstract

31.6  Friday, Jan. 4  Getting a leg up: the evolution of novel abdominal appendages in sepsid flies BOWSHER, J.H.*; NIJHOUT, H.F.; NAGY, L. M.; University of Arizona; Duke University; University of Arizona jhb4@email.arizona.edu

A major goal of the recent re-synthesis of developmental and evolutionary biology is to understand how evolutionary changes in the molecular processes of development result in changes in morphology. This study examines how novel characters evolve through an analysis of abdominal appendage development in flies of the family Sepsidae. Sepsid abdominal appendages are short, jointed structures the males use during mating. As these abdominal appendages superficially resemble other insect appendages, I investigated whether the developmental machinery responsible for the patterning of other appendages has been co-opted in the evolution of these novel abdominal appendages. Cauterization experiments determined that the appendages develop from the abdominal histoblasts as opposed to an imaginal disc. This is the first documented instance of such a complex structure arising form histoblast cells. The investigation of various genes involved in appendage patterning revealed that sepsid abdominal appendages are patterned similarly to the coxa of a leg, with no evidence of a proximal-distal axis. Currently, proteomic approaches are being employed to identify other genes expressed during the development of these novel structures.