Meeting Abstract

57.2  Thursday, Jan. 6  Evolution of locomotor systems in frogs JORGENSEN, M.E.*; REILLY, S.M.; Ohio University mj207406@ohio.edu

Reconstruction of ancestral character states can enhance our understanding of the evolution of organisms as well as provide a basis from which one can construct hypotheses about trait evolution, ecology, and function in a taxonomic group. The anuran pelvic system is a prime candidate for this analysis as recent studies have posited that long-distance jumping evolved in a more stepwise manner than previously suggested. We examined osteological traits of the pelvic region to conduct the first phylogenetic analysis of the relationships between pelvic systems and locomotor modes in frogs. Traits from the sacrum and ilium and two traits from the urostyle were sampled in species representing 5 paleotaxa and 70 extant taxa. Results of the ancestral character state reconstruction using maximum likelihood show that the lateral-bender, walker/ hopper condition is both basal and generally conserved across the Anura. Long-distance jumping frogs do not appear until well within the Neobatrachia. The sagittal-hinge pelvis is correlated with long-distance jumping in terrestrial frogs, however, it evolved convergently multiple times in crown group anurans with the same four pelvic traits. Arboreal jumping has appeared in multiple crown lineages as well, but with divergent patterns of evolution involving three pelvic types. The fore-aft slider pelvis appears independently in three different locomotor modes and thus, is a more complex system than previously thought. Finally, we posit that a bicondylar sacro-urostylic articulation originally provided axial rigidity to lateral bending behaviors such as burrowing or walking and only later was an exaptation to long-distance jumping.