Meeting Abstract

102.4  Wednesday, Jan. 7  Tail Elongation and Patterns of Regional Growth in Salamanders VAGLIA, J.L.*; BABCOCK, S.K.; WHITE, K.; CASE, A.; SMITH, K.; DePauw University jvaglia@depauw.edu

While the morphology and function of the vertebral column are conserved across vertebrate groups, it exhibits variation in the number of vertebrae comprising the different axial regions. Typically the number of vertebrae an organism will have post-embryonically is determined during embryogenesis via the development of paired somites. However, studies show that salamanders (Amphibia:Urodela) add caudal vertebrae throughout life. Our research investigates the phenomenon of continual axial elongation in salamanders, with current emphasis on two species of the genus Eurycea (Plethodontidae), E. cirrigera and E. longicauda. Our goals were to 1. determine whether and to what extent Eurycea adds vertebrae through the life cycle, 2. assemble centrum length profiles of tail vertebrae, and 3. build upon our understanding of axial elongation in plethodontids. Larval, juvenile, and adult specimens were collected from field sites in central Indiana. Whole specimens were cleared and stained for bone and cartilage. Data collected include snout-vent length (SVL), tail length (TL), vertebral counts and centrum lengths. Both Eurycea species had TLs that surpassed SVL following metamorphosis. Increased TLs were associated with increased numbers of caudal vertebrae. Posterior to the base, tails exhibited regional variation in centrum lengths, similar to patterns observed for other salamander species (Babcock and Blais, 2001). Variation amongst species at the tail base might reflect phylogenetic history and/or design changes accompanying tail autotomy and elongation. Patterns in SLV/TL, caudal numbers and centrum lengths also varied across the life cycle. This suggests that metamorphosis represents an important transition in mechanisms that enable elongation of the posterior body axis.