Meeting Abstract

P3.15  Saturday, Jan. 5  Diet-induced developmental gut plasticity: Implications for the evolution of alternate feeding strategies within and between species LEDON-RETTIG, C.*; PFENNIG, D.W.; NASCONE-YODER, N.; Univ. North Carolina, Chapel Hill; Univ. North Carolina, Chapel Hill; North Carolina State Univ. ledonret@email.unc.edu

Many species exhibit phenotypic plasticity in digestive tract morphology and physiology, and this plasticity is thought to enable individuals to respond adaptively to unpredictable or novel resources. Yet the role of such plasticity in facilitating the evolution of interspecific differences is relatively unexplored. Spadefoot toad tadpoles exhibit both intra- and inter-specific variation in feeding strategies. Within species, some individuals feed on detritus and develop an elongate gut, whereas others feed on fairy shrimp and develop a much shorter gut. We compared diet-specific gut development in two spadefoot species that differ in propensity to eat shrimp (Spea multiplicata and Sp. bombifrons), and a third species that feeds exclusively on detritus (Scaphiopus couchii). Tadpoles of all three species exhibited significantly shorter guts when fed shrimp than when fed detritus, and this divergence in morphology was apparent within hours of feeding. Diet-induced cellular proliferation was most pronounced in shrimp-fed larvae of Sp. bombifrons, the species that uses this resource the most in nature. In contrast, shrimp only moderately elicited proliferation in Sp. multiplicata, and did not elicit proliferation in Sc. couchii. Thus, shrimp appears to induce morphological changes in the guts of all three species, but can only elicit physiological plasticity in the two species that actually use this resource. These results suggest that diet-induced developmental plasticity may have promoted the evolution of alternative feeding strategies in the larvae of certain spadefoot toad species.