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First published online January 31, 2007
Journal of Experimental Biology 210, iii (2007)
Copyright © 2007 The Company of Biologists Limited
doi: 10.1242/jeb.02723
Inside JEB |
DECISIONS, DECISIONS
laura{at}biologists.com
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Deep in the Panamanian jungle, red-eyed treefrogs lay their eggs on leaves above water. These eggs are a tasty snack for snakes, but the developing embryos have a trick up their sleeve to avoid being eaten. When they feel the tell-tale vibrations of a snake attack, they hatch prematurely and drop into the water below. But this strategy can be risky: if embryos hatch too early, they might escape from the snake's jaws, but they are at greater risk of being munched by predators in the water below. Embryos decide when to hatch by sampling information about vibrations, using their duration and the gaps between vibrations to help them make potentially life-saving decisions. If they don't wait long enough, though, they might not gather enough information to make an informed decision; if they wait too long, however, they are more likely to become a snake's snack.
Interested to know what strategy the frog embryos use to make hatching decisions, Karen Warkentin and colleagues at Boston University and the Smithsonian Research Institution, Panama, vibrated clutches of eggs in patterns which they knew induced similar amounts of hatching (p. 614). They varied vibration cycle length – vibration duration and the gaps between vibrations – and found that embryos hatched sooner when there were more cycles of vibration in a shorter space of time, but if the vibration cycles were longer, they didn't sample as many cycles before hatching. This shows that the embryos are balancing a trade-off between how valuable information is to them, and how risky it is to obtain that information: they don't hang around too long and risk being eaten, even if they haven't sampled as much information.
References
Warkentin, K. M., Caldwell, M. S., Siok, T. D., D'Amato, A. T.
and McDaniel, J. G. (2007). Flexible information sampling in
vibrational assessment of predation risk by redeyed treefrog embryos.
J. Exp. Biol. 210,614
-619.
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