Mutualists US (IMAGE) Colorado State University Caption From 2004 to 2018, researchers found that Western states had a 4.7 percent increase in mutualists. Credit America's Wildlife Values research team 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.