Ant-caterpillar (image) Max-Planck-Gesellschaft Caption The beginning of a beautiful friendship? In some interspecies relationships, ants "tend" to a single caterpillar, preventing it from being attacked by predators. In return for such protection services, they are rewarded with the larva's sugary secretions. New research has now shown that the rate of evolution in a mutualistic relationship does not depend only on the type of interactions, but also on the number of individuals involved. Credit MPI for Chemical Ecology/ Ian Baldwin / Alexander Weinhold Usage Restrictions None 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.