My name is Dana Hawley, I’m an associate professor in biological sciences at Virginia Tech and I study the ecology and evolution of infectious diseases. So our work is on a songbird disease system, it’s a pinkeye bacterial disease that a very common songbird species gets and what we noticed in our research is that over time this pinkeye disease is causing birds to feel more and more sick. The pathogen is essentially evolving to become more and more harmful to its host. We hypothesized that the immune systems of these birds may be what’s providing an incentive for the pathogen to become more and more harmful over time and the reason we hypothesized this is that we know birds can recover in the wild when they get this disease and when they recover they don’t have a complete immune response so the immune response essentially leaves a small window of opening. So essentially, having some pre-existing immunity favored these more harmful strains of bacteria. We then took that information from our lab experiments and we put that into a computer model and we simulated the evolution of the pathogen over time and we found that our data from our lab experiments when when put into a model led to an almost doubling of the amount of harm that that bacteria caused to its host. The reason that more harmful pathogens typically can overcome existing immunity is that they replicate faster in their hosts but it also gives them a benefit because it means that they can still replicate even in the presence of a strong existing host immune response. This work came out of a large collaborative effort involving mathematicians, ecologists, and microbiologists. and we were really able to I think generate some exciting information about basic principles that can then be applied to potentially improve human and animal health.