Ontogenetic effects of hatching plasticity in spotted salamanders due to larval and egg predators

Meeting Abstract

P1.84  Thursday, Jan. 3  Ontogenetic effects of hatching plasticity in spotted salamanders due to larval and egg predators BROWN-WILUSZ, L.H.*; LANDBERG, T; University of Connecticut, Storrs; University of Connecticut, Storrs leah.brown-wilusz@uconn.edu

Hatching plasticity allows amphibians to alter their development in response to the threat of immediate or future predation. Developing embryos attacked by egg predators (immediate) are expected to hatch out of the egg early while the presence of larval predators (future) may induce delayed hatching. Early hatching may incur costs such as reduced escape swimming performance and/or slower growth and developmental rates in future life stages. If exposed to both predators, the threat of immediate predation is expected to outweigh future potential predators. We created a laboratory experiment to see how spotted salamander embryos (Ambystoma maculatum) respond to combinations of (non-lethal) egg and larval predators. Eggs from six clutches were separated into four treatment groups, each replicated twice: no predators, egg predator only (caddisfly larvae), larval predator only (Ambystoma opacum), and both predators. Developing embryos and hatchlings were staged daily and scored as hatched or unhatched. After hatching, five individuals per tank (n=48) were photographed and entered into lethal predation trials with fish predators (Lepomis sp.). To determine if early ontogenetic changes in development affect future life stages, we followed the growth and development of the larvae through to metamorphosis. Ontogenetic trajectories of morphological characteristics (snout-vent length, tail length, tail height, and tail area) were constructed from weekly photographs of 150+ animals. Preliminary analysis has revealed that the animals reared with larval predators (only) had larger tail areas than animals in the three other treatments. This indicates that the morphological response to future larval predators is inhibited by the more immediate threat of egg predators.

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