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

• Published in: Ecology and evolution 2024-02, Vol.14 (2), p.e10915-n/a
• Main Authors: Smaga, Christopher R., Bock, Samantha L., Johnson, Josiah M., Rainwater, Thomas, Singh, Randeep, Deem, Vincent, Letter, Andrew, Brunell, Arnold, Parrott, Benjamin B.
• Format: Article
• Language: English
• Subjects: Alligator mississippiensis; Alligators; Altitude; Aquatic reptiles; Body mass; Body mass index; developmental plasticity; Eggs; Environmental Sciences & Ecology; Evolutionary Biology; Fat body; Influence; life history; maternal provisioning; Metabolism; Offspring; Phenotypic variations; Populations; Provisioning; Temperature; temperature‐dependent sex determination
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.10915

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. The influence of incubation temperature, not maternal provisioning, varies across populations of the American alligator. Responses to incubation temperature are a larger source of interpopulation trait variation relative to maternal provisioning and may be more likely to be modified by selection.