SREL Reprint #2039
Effects of incubation temperatures on characteristics of hatchling American alligators
Justin D. Congdon1, R. U. Fischer1, and Robert E. Gatten, Jr.2
1Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA
2Department of Biology, University of North Carolina, Greensboro, NC 27412, USA
Abstract: We examined the effects of egg qualities and incubation temperatures on characteristics of hatchling American alligators. Alligator eggs were collected from the Rockefeller Wildlife Refuge, Louisiana, and transported to the Savannah River Ecology Laboratory near Aiken, South Carolina. Eggs from each clutch were initially incubated at either 30 C to produce only females or 34 C to produce only males. After 40 days of incubation, the eggs were distributed among four final temperatures (28, 30, 32, 34 C) for the remaining third of development. Egg and hatchling lipids were extracted with petroleum ether and hatchling nitrogen content was determined using the micro-Kjeldahl procedure.
Egg yolk averaged 40.7% non-polar lipids and parental investment ratios (hatchling yolk lipids / egg lipids) averaged 66% and did not vary significantly among incubation treatments. Individual hatchling characteristics (snout-vent length, carcass lean dry and lipid mass, yolk sac lean dry and lipid mass) were not significantly influenced by initial incubation temperature and, with the exception of hatchling yolk lean dry mass, were not significantly influenced by final incubation temperatures. Multivariate analysis of hatchling characteristics revealed that maternal effects and incubation temperatures during the final third of development appear to have major impact on hatchling characteristics. Based on these results, the "decision" to produce primarily male or female offspring would first be based on characteristics of the female parent and secondarily on the nest temperatures influenced by nest site selection. The effects of nest temperatures would first determine the sex through the first two thirds of incubation and subsequently influence the quality of the offspring during the final third of development.
Keywords: Alligator; Alligator mississippiensis Eggs; Embryo development; Hatchlings; Incubation temperatures; Lipids; Yolk reserves
SREL Reprint #2039
Congdon, J.D., R.U. Fischer, and R.E. Gatten, Jr. 1995. Effects of incubation temperatures on characteristics of hatchling American alligators. Herpetologica 51:497-504.
This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).