Meeting Abstract

P3.24  Thursday, Jan. 6  Effects of hatching age and predator cues on the onset of feeding in red-eyed treefrogs SCHLEIER HERNANDEZ, S.L.*; WARKENTIN, K.M.; University of Puerto Rico, Humacao; Boston University, MA schleier.sandra@gmail.com

Red-eyed treefrogs, Agalychnis callidryas, can hatch at different ages and stages of development. Embryos under attack by egg predators hatch early to escape while undisturbed eggs hatch later, reducing mortality from aquatic predators. Hatched tadpoles develop faster than equal-aged embryos. Also, for hatched tadpoles, cues from aquatic predators can reduce growth rates and in some cases early hatchlings have an initial growth advantage as tadpoles. All tadpoles hatch with yolk reserves, and prior work indicated that early hatchlings begin feeding before late hatchlings. We used hourly observations of feces presence/absence to assess the onset of feeding in 37 individually reared tadpoles from a single egg cohort hatched at four ages (4–7 d), then measured gut transit times once all animals were producing feces. We also tested the effect of chemical cues from aeschnid dragonfly nymphs, fed tadpoles, on the onset of feces production after hatching at 5 days (N = 25 cue and 25 no cue tadpoles). Compared to full-term hatchlings, the earliest-hatched animals began producing feces absolutely earlier in development (182 vs. 214 h post-fertilization) but relatively later after hatching (74 vs. 35 h delay). Gut transit times at age 8 d were ~30% faster for early-hatched animals (4.25 vs. 6 h). Aeschnid cues delayed the appearance of feces slightly (3 h) but significantly. Collectively these results show clear and immediate effects of the early environment of A. callidryas, including egg vs. water and aquatic predator cues, on their digestive system development. This may contribute to the variation in tadpole growth rates observed later in life.