Packrat and Juniper (IMAGE) University of Utah Caption A packrat, also known as a woodrat, from the Great Basin of Utah is surrounded by mildly toxic juniper leaves that make up much of its diet. When climate warming eliminated juniper trees from what is now the Mojave Desert between 18,700 and 10,000 years ago, packrats there had to eat much more toxic creosote bushes, which replaced juniper. A University of Utah study has scanned the genetic blueprint of packrats from the Great Basin and the Mojave, and has narrowed to 24 candidate genes the search for genes that produce enzymes allowing Mojave packrats to eat poisonous creosote resin. Credit Denise Dearing, University of Utah Usage Restrictions None License Licensed content 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.