Ecological Plasticity and the Future of the Argentine Giant Tegu (Salvator merianae Dumeril and Bibron, 1839) in the Southeastern US

Walter E. Meshaka Jr.^1,*, Frank J. Mazzotti², Kevin M. Hoffman¹, and Michael R. Rochford²

¹Section of Zoology and Botany, State Museum of Pennsylvania, Harrisburg, PA 17120. ²Fort Lauderdale Research and Education Center, University of Florida, Davie, FL 33314. *Corresponding author.

Southeastern Naturalist, Volume 18, Issue 4 (2019): 659–676

Abstract
Salvator merianae (Argentine Giant Tegu) is an invasive exotic species established in 2 as yet unconnected populations in central and southern Florida. Despite intense trapping, this mid-level carnivore remains well-established in a portion of extreme southern mainland Florida where it was first released 20 y ago. High fecundity, nest-guarding, rapid growth to large body size, and broad trophic width by which it negatively impacts wildlife contribute to its success as a colonizing species. Native to more temperate habitat, it experiences a defined winter and summer in South America unlike the wet–dry seasons of southern Florida. We conducted a qualitative comparison of key life-history traits from source areas to those of southern Florida that provided a measure of its ecological plasticity and formed the basis for expectations associated with northward expansion. Our examination of 1168 specimens collected during 2011–2017 revealed an overlap between the sexes in timing of fat storage prior to brumation and late-winter–early-spring peak in gonadal size. Females were ovigerous during March–May and possibly June, and clutch size averaged 28.6 eggs. Hatching was possible during May–August, and both sexes reached sexual maturity by 2 y of age. In this subtropical system, length of seasonal activity, gonadal cycles, and size and age at sexual maturity differed from those of source areas, indicative of the degree of plasticity among these traits over a short period of time. We found that the climate of the Southeast is amenable to the colonization of this vagile species. Our findings are suggestive that a return to the strongly selected seasonal activity and gonadal cycles of central Argentina will accompany the Argentine Giant Tegu in its northward dispersal into more temperate conditions even as it retains a somewhat relaxed cycle in southern Florida.

Download Full-text pdf (Accessible only to subscribers. To subscribe click here.)