Meeting Abstract

P3.113  Friday, Jan. 6  Carryover effects of larval digestive plasticity in postmetamorphic red-eyed treefrogs, Agalychnis callidryas JENNEY, C.R.*; BOUCHARD, S.S.; WARKENTIN, K.M.; Otterbein Univ.; Otterbein Univ.; Boston Univ.

Larval environment has a profound effect on post-metamorphic nutrition in red-eyed treefrogs. Small froglets emerging from high density larval environments begin feeding sooner and grow at a faster rate than large froglets from low density environments. Additionally, froglet insect intake does not scale with body size despite large differences in froglet mass. We assessed to what extent these patterns could be attributed to effects of larval plasticity that carry over post-metamorphosis. We hypothesized that larvae from high densities would have longer guts (increasing digestive efficiency) and smaller livers (reducing metabolic costs) in response to lower per capita food resources. We reared larvae at three densities (5, 25 and 45 individuals per 400 L tank), and euthanized 10 size-matched larvae and 10 froglets from each density. We dissected and weighed the guts, livers, and fat bodies of all individuals. The guts were uncoiled and photographed, and gut length and area were assessed using image analysis software. As predicted, guts of high- and medium-density larvae were 23% longer than those of low-density larvae, and livers and fat bodies were significantly smaller. Low-density froglets were three times heavier than high-density froglets. Despite this extreme size difference, gut length did not vary with density, although high- and medium-density guts were lighter and thinner than low-density guts. High- and medium-density froglets also had proportionately smaller livers and fat bodies than low-density froglets. These results confirm carryover effects of larval plasticity post-metamorphosis and likely have important metabolic implications for froglets leaving the pond.