Although curly-tailed lizard hatchlings are larger than anole hatchlings, they probably are not large enough to eat other lizards. So, continued predation by curly tails after the hurricane probably does not explain the difference between the predator and no-predator islands.
A second explanation is that the anoles, forced off the ground and into the bush by the rampaging curly-tailed lizards, may have deposited their eggs in less secure places, such as trees rather than rock holes or other more protected sites. This would make the eggs deposited more vulnerable to hurricane winds and water.
The third explanation suggests that,because the anoles were forced to shift their habitat, moving far up into the bushes to avoid the curly tails, they may have had reduced hunting success or mating opportunities so that in the presence of the predator, they were producing fewer eggs, which in turn would result in fewer potential hurricane survivors.
"We have three hypotheses, but it's not clear if any one alone explains what happened," says Losos. "We speculate that the presence of a predator, besides reducing the population, also changes the ecology in such a way that the the anole populations are more vulnerable to a natural catastrophe, but we still don't know what is the exact causal mechanism."
Losos says that the three biologists will continue to monitor the islands and hope to restart the experiment in the spring of 2003. The intent is to study how the anole lizards adapt to the new habitats they must occupy in the presence of curly-tails.
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Contact: Susan Killenberg McGinn
susan_killenberg@aismail.wustl.edu
314-935-5254
Washington University in St. Louis
11-Jul-2001