Meeting Abstract

P3.99  Sunday, Jan. 6  Variation and integration in amphibian dentitions: insights about sex and size from Silurana (Xenopus) tropicalis GRIECO, TM*; CAM, SB; HLUSKO, LJ; University of California, Berkeley; University of California, Berkeley; University of California, Berkeley grieco@berkeley.edu

The phenotypic variation expressed in populations is filtered through developmental and physiological processes occurring during individual lifetimes. Dental phenotypes allow us to study the relative influences of these processes because the functional constraints of the oral apparatus are superimposed on the development of the cranium. Amphibians, with their largely homodont, marginal dentitions spanning multiple jaw bones, provide a good model in which to study these various influences. Previous work in salamanders highlights size and/or shape differences in premaxillary teeth compared to maxillary teeth, and that this effect is sexually dimorphic (displayed in males only), suggesting that dental variation could be constrained by tooth bearing bones or could be differentially hormonally controlled. To examine this further, we turned to the sexually size dimorphic frog Silurana (Xenopus) tropicalis to look for evidence of these mechanisms in its dentition. Cranial linear measurement data suggest that overall head proportions are constrained to 1:1, and body length is less strongly correlated with the size of the jaw and dentition. Sexual dimorphism is apparent in all traits, but larger individuals/females appear to be more variable in maxillary length than smaller individuals/males. The consequences of this relationship for the dentition are further evaluated by tooth count data. We discuss the implications of these craniodental data for morphological integration in and evolvability of amphibian dentitions.