Lizards in the Mountains: Temperature-oxygen interactions shape performance & potential in montane ectotherms

In this talk I will describe how we tested, rejected, and refined hypotheses about how temperature interacts with oxygen availability to shape organismal performance and thermal limits in ectotherms. To explain seemingly contradictory reports in the literature and our own experimental results with the gartersnake Thamnophis elegans, we proposed an integrated framework: the Hierarchical Mechanisms of Thermal Limitation hypothesis, which explains how variation in oxygen availability can determine mechanisms under-lying performance variation across temperatures. We then tested this hypothesis in a series of experiments with the upslope-colonizing lizard Podarcis muralis. Our empirical results supported our predictions and we developed a mathematical framework, coined Temperature-Oxygen Performance Surfaces (TOPS), to estimate the sensitivity of thermally-dependent traits to variation in oxygen availability. However, additional experiments with high-elevation specialist lizards (Iberolacerta bonnali) suggest that there may be more complicated processes at play, especially in regard to aerobic metabolism and mitochondrial function across levels of oxygen availability.

 

Recent publications:

Bodensteiner, BL*, EJ Gangloff*, L Kouyoumdjian, MM Muñoz, & F Aubret. 2021. Thermal-metabolic phenotypes of the lizard Podarcis muralis differ across elevation, but converge in high elevation hypoxia. Journal of Experiment Biology 224:jeb.243660. doi: 10.1242/jeb.243660

Gangloff, EJ, S Spears, L Kouyoumdjian, C Pettit, F Aubret. 2021. Does hyperoxia restrict Pyrenean rock lizards Iberolacerta bonnali to high elevations? Diversity 13:200. doi: 10.3390/d13050200.

Gangloff, EJ*, TS Schwartz*, R Klabacka, N Huebschman, AY Liu, AM Bronikowski. 2020. Mitochondria as the central character in a complex narrative: Linking genomics, energetics, and pace-of-life in natural populations of garter snakes. Experimental Gerontology 137:110967. doi: 10.1016/j.exger.2020.110967. *Co-first author