Meeting Abstract

P1.61  Tuesday, Jan. 4  Lung Development in Lungless Salamanders! KERNEY, Ryan ; LEWIS, Zachary*; HANKEN, James; Dalhousie University, Biology Department, Halifax, NS B3H 4J1, Canada ; Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, United States; Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, United States zlewis@oeb.harvard.edu

Lungs have played a key role in the extraordinary adaptive diversification of terrestrial vertebrates. Yet, independent instances of lung loss have occurred within each of the three clades of living amphibians—Caudata, Anura, and Gymnophiona. The morphological and molecular developmental pathways involved in lung loss remain unexplored. However, growing understanding of the mechanisms of pulmonary development presents the opportunity to examine this issue in greater detail, beginning with morphological description. We compare lung morphogenesis in a lunged salamander (Ambystoma mexicanum) to the lungless plethodontid salamander Plethodon cinereus. Both species undergo similar early stages of pulmonary morphogenesis, but early lung rudiments regress in later-stage P. cinereus. The presence of pulmonary vestiges in P. cinereus indicates that lung loss likely involves the disruption of proper lung growth or maintenance, and not the specification of pulmonary rudiments. Formation of vestigial lungs in P. cinereus suggests pleiotropic roles for the initial regulatory cascades of pulmonary specification, or possible conservation of essential inductive interactions between lung rudiments and surrounding tissues. These results have implications for both the evolution of lung loss and the developmental mechanics of lung development. Supported by NSF (EF-0334846, AmphibiaTree) to JH.