Demographic correlates of variable egg survival for a tropical lizard.

Anolis limifrons is a small iguanid lizard that is found in lowland rainforest in Central America. Important life attributes include early maturity (3-4 mo), multiple clutches of a single egg per breeding season, and low survival. Population turnover is essentially annual as less than 5% adults live more than one year. My objectives were to resolve the following specific questions: 1) Where are eggs laid? 2) Does survival differ among different types of oviposition site? 3) How is the survival of eggs related to the density and age distribution of lizards at different areas? Most eggs are laid beneath litter on the ground. Eggs laid aboveground are placed in accumulations of soil and litter in stumps, crevices in buttressed trees and vines, holes in trees, and on the tops of logs. Eggs were found in aboveground sites in proportion to the abundance of those sites. The major cause of mortality was predation by Solenopsis ants. Judging by the ratio of eggs known to have hatched to those that were predated, survival did not differ among the various types of oviposition site. Study areas with high egg survival in the middle of the wet season had relatively more young (<4-6 mo old) lizards at the end of the wet season than areas with low egg survival. The strong correlation between the relative number of young individuals and egg survival is a consequence of the seasonal cycle of growth and reproduction. Most eggs are laid in the wet season (May-December). Hatchlings complete growth during the dry season (January-April) and become reproductive adults in their second wet season. However, because hatchlings can grow to reproductive size in approximately 3 months, individuals that hatch early in the wet season may themselves produce offspring that will be <4-6 mo old in the late wet season. The relative survival of juveniles (eggs) and adults is an important datum for many theories of life history evolution. For A. limifrons, survival of eggs was two to three times more variable than survival of lizards on both temporal and spatial scales. Comparative data for reptiles are not available to put this information into an evolutionary prespective.