Lizard on Rock (image) Penn State Share Print E-Mail Caption A new study by Penn State researchers reveals that lizard with ancestors who were frequently exposed to stressful encounters with invasive fire ants have an improved immune response to stress. Credit Gail McCormick, Penn State Usage Restrictions Image credit must be provided alongside image. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.