WCH9: The Effect of Constant Egg Incubation Temperatures across Life Stages in the Brown Anole

Ectotherms are well known for having an inordinate fraction of their biology linked to thermal conditions. Many of their demographic vital rates and life-history traits are influenced by temperature-dependent physiological processes. This connection between temperature and physiology is particularly apparent during embryonic development, especially in oviparous species lacking parental care after eggs are laid. Jenna Pruett, a PhD candidate in the Warner lab at the University of Auburn, investigated the effect of constant egg incubation temperatures across life stages in the brown anole. Many studies of this nature lack enough temperature treatments to fully characterize the thermal reaction norm and frequently do not follow the offspring past hatching. Jenna sought to fill these knowledge gaps by answering the questions:  1) How does constant incubation temperature affect embryonic development? 2) Do these effects vary across a small geographic scale? and 3) Do effects carry over into later life stages?

To do this Jenna incubated ~350 brown anole (Anolis sagrei) eggs from different locations across eight different constant incubation temperatures. When examining hatching success, temperature seemed to be the only driver of success. Meanwhile, hatchling mass had a significant interaction between temperature and location potentially indicating that lizards at specific locations respond differently to different thermal regimes during development. Overall, she found that geographic variation doesn’t impact hatching success but changes how phenotypes respond to temperature.

The second part of the experiment involved a large release and recapture experiment on experimental spoil islands off the coast of Florida. Hatchlings were released early and late in the summer and then were recaptured the following fall and spring to determine survival to recapture. Jenna found that survival to recapture was influenced by incubation temperature, release date, and an interaction between the two, showing that timing is everything and that in this case the optimal temperature for the greatest survival varied across life stages.

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