The Effect of Red Imported Fire Ant Venom on Whole Body Performance and Erythrocyte Lysis of Eastern Fence Lizards, Sceloporus undulatus

Open Access
Goldy-brown, Mark Joseph
Area of Honors:
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Tracy Lee Langkilde, Thesis Supervisor
  • Sarah Mary Assmann, Honors Advisor
  • pre-adaptation
  • invasive species
  • venom
  • physiological resistance
  • fire ants
  • fence lizard
Invasive species are a worldwide threat, contributing to the disruption of ecosystems and reductions in native biodiversity. Native species that are faced with ecologically novel invasive species may be under strong selective pressure to adapt to the new threats these invaders posed. Some native species, however, may be pre-adapted to deal with invasive threats due to existing adaptations to native species. The Red Imported Fire Ant, Solenopsis invicta, was introduced into the southeastern U.S. over 75 years ago and has since spread northward. Solenopsis invicta are venomous predators that can quickly paralyze and kill even large vertebrates. Native Eastern Fence Lizards (Sceloporus undulatus) from S. invicta-invaded sites have altered morphology and behavior that allow them to survive encounters with these invasive ants. These lizards, however, do not appear to have developed increased tolerance to fire ant venom. We test whether this apparent lack of adaptation is due to pre-adaptation to the venom of two native fire ant species (Solenopsis geminata and Solenopsis xyloni). We examined the effects of fire ant venom on the whole-body performance (tested via righting ability) and blood lysis of Sceloporus undulatus from S. invicta-invaded and uninvaded populations in the southern U.S., where these lizards overlap with native fire ants, and compare these to effects of fire ant venom on lizards from three northern sites that are outside the native fire ants’ ranges. We found no evidence that Eastern Fence Lizards have evolved increased physiological resistance to fire ant venom: the impact of fire ant venom on righting ability and blood lysis did not differ between S. invicta-naïve versus experienced populations, or between lizard populations with or without historical exposure to fire ants. Testing for effects of prior exposure to closely related and ecologically-similar native species can provide insight into the prevalence of adaptation and importance of pre-adaptation, of native species to invasive threats.