Meeting Abstract
Red-eyed treefrogs (Agalychnis callidryas) lay egg clutches on vegetation over Neotropical ponds, and tadpoles fall into the water upon hatching. Embryos are subject to heavy predation; in prior work, half the clutches monitored at a pond were attacked by social wasps (Polybia rejecta). Some embryos escape from attacks by hatching rapidly and prematurely, but at a cost of higher predation risk as tadpoles. Predator-induced hatching begins at age 4 days and is initially highly variable among clutches. With development, escape success improves and becomes more consistent, so most 5-d embryos survive attacks. To understand how developmental changes in embryo behavior, decisions, and escape performance contribute to their changing fates in attacks, we recorded macro-video of wasp interactions with 4 and 5-d embryos near a pond in Panama. Escape success varied from 0–100% among studied clutches, improving strongly with development. From our video analysis, we identified two major changes that contribute to the developmental increase in survival. First, development increased the chance that an embryo would hatched pre-emptively, in response to wasp activity on its clutch, rather than waiting for a direct attack that ruptured its egg. Almost all of these hatchlings survived. Second, development improved embryos’ chances of escaping from egg capsules that were directly attacked and ruptured by a wasp. Such escapes occurred during both intense struggles and periods when the wasp stepped away from the ruptured egg. Thus, it appears that changes in both embryo decisions during attacks on their clutch and escape-hatching performance under direct attack contribute to ontogenetic changes in embryo fates.
