Stahler_Yellowstone wolves (1) (IMAGE) University of Oxford Caption Members of the Druid Peak Pack in Yellowstone National Park engage in a game of chase. The gray colored wolf on the left represents the homozygous gray phenotype, while the black colored wolf on the right represents the K-locus black phenotype. Credit: Daniel Stahler/NPS Credit Daniel Stahler/NPS Usage Restrictions No restrictions. License Public Domain 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.