Higher Temperature Tolerance in Ectotherms Facing Threats from an Invasive Predator

Angeli, Nicole F.*

Biodiversity Research and Teaching Collections

Department of Wildlife and Fisheries Sciences

Applied Biodiversity Sciences Program

Texas A&M University

College Station, TX

nicoleangeli1@gmail.com

*Current address

Alabama Cooperative Wildlife and Fisheries Research Unit

School of Forestry and Wildlife Sciences

Auburn University

Auburn, AL

Miles, Donald B.

Department of Biological Sciences and Ohio Center for Ecology and Evolutionary Studies

Ohio University

Athens, OH

Fitzgerald, Lee A.

Biodiversity Research and Teaching Collections

Department of Wildlife and Fisheries Sciences

Applied Biodiversity Sciences Program,

Texas A&M University

College Station, TX

Predator and prey relationships are powerful drivers of biological change, and less is known about the role of physiology than morphology or behavior in response to novel predators. Considerable attention has been given to testing the effects of abiotic factors on thermoregulatory traits, yet the effects of novel predators on thermoregulatory traits of native prey are largely undocumented. Thermal lability across populations affected by novel or persistent threats may offer insights into the ability of physiological plasticity to promote species persistence. Ground lizards (Pholidoscelis spp.) are widely distributed habitat generalists that live in warm heterogeneous environments. We measured physiological traits at ten geographically isolated sites across the Puerto Rican Bank for more than 80 individuals of the widespread species Pholidoscelis = Ameiva exsul. We calculated a measure of overheating safety margins for these populations by taking the difference between heat tolerance and preferred body temperatures. We found statistically significant, directional selection on heat tolerance of the lizards and larger overheating safety margins where mongoose co-occurred with the lizards. Further, we found similar fitness across all populations indicating some capability of P. exsul to survive the invasion of a novel predator. This is one of only a few studies to show lability in critical thermal maximum. Despite limits on evolution of thermal tolerance, the ability of species to respond physiologically to heat stress may be one way for species to persist in a changing world.