Summary: Journal of Herpetology, Vol. 37, No. 2, pp. 309314, 2003
Copyright 2003 Society for the Study of Amphibians and Reptiles
Consequences of Extended Egg Retention in the Eastern Fence Lizard
DANIEL A. WARNER1
AND ROBIN M. ANDREWS
Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
ABSTRACT.--Egg retention beyond the normal time of oviposition occurs frequently in oviparous squamate
reptiles and is thought to be a response to unfavorable nesting conditions. During studies of the Eastern
Fence Lizard (Sceloporus undulatus), we obtained data on the effects of extended egg retention on embryonic
development, hatchling phenotypes, and posthatching survival under natural field conditions. Females that
retained eggs beyond the normal time of oviposition produced heavier eggs with embryos more advanced
(by one stage unit) at the time of oviposition than females that did not retain eggs for extended periods.
Egg retention did not affect any hatchling phenotype (i.e., body size, thermal preference, running speed,
desiccation rate, growth rate) but had a significant positive effect on posthatching survival in the field.
However, the mechanism by which extended egg retention affects posthatching survival remains unclear.
Our results have implications for the evolution of viviparity, but carefully designed experiments are needed
to further understand the causes and consequences of extended egg retention.
The retention of eggs in the oviduct beyond
the normal time of oviposition is common in