SREL Reprint #3851

The influence of incubation temperature on offspring traits varies across northern and southern populations of the American alligator (Alligator mississippiensis)

Christopher R. Smaga1,2, Samantha L. Bock1,2, Josiah M. Johnson1,2, Thomas Rainwater3,4, Randeep Singh3, Vincent Deem5, Andrew Letter5, Arnold Brunell5, and Benjamin B. Parrott1,2

1Eugene P. Odum School of Ecology, University of Georgia, Athens, Georgia, USA
2The University of Georgia's Savannah River Ecology Laboratory, Aiken, South Carolina, USA
3Belle W. Baruch Institute of Coastal Ecology and Forest Science, Clemson University, Georgetown, South Carolina, USA
4Tom Yawkey Wildlife Center, Georgetown, South Carolina, USA
5Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission, Gainesville, Florida, USA

Abstract: Maternal provisioning and the developmental environment are fundamental determinants of offspring traits, particularly in oviparous species. However, the extent to which embryonic responses to these factors differ across populations to drive phenotypic variation is not well understood. Here, we examine the contributions of maternal provisioning and incubation temperature to hatchling morphological and metabolic traits across four populations of the American alligator (Alligator mississippiensis), encompassing a large portion of the species' latitudinal range. Our results show that whereas the influence of egg mass is generally consistent across populations, responses to incubation temperature show population-level variation in several traits, including mass, head length, head width, and residual yolk mass. Additionally, the influence of incubation temperature on developmental rate is greater at northern populations, while the allocation of maternal resources toward fat body mass is greater at southern populations. Overall, our results suggest that responses to incubation temperature, relative to maternal provisioning, are a larger source of interpopulation phenotypic variation and may contribute to the local adaptation of populations.

Keywords: developmental plasticity, life history, maternal provisioning, temperature-dependent sex determination

SREL Reprint #3851

Smaga, C. R., S. L. Bock, J. M. Johnson, T. Rainwater, R. Singh, V. Deem, A. Letter, A. Brunell, and B. B. Parrott. 2024. The influence of incubation temperature on offspring traits varies across northern and southern populations of the American alligator (Alligator mississippiensis). Ecology and Evolution 14(e10915).

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).