In this model, we expect that AMPs are evolutionary liabilities in the absence of infection, and that host ecology and associated pathogen pressure will drive the evolution of AMP content both at the level of broad AMP gain/loss, and also of AMP expression: species with strong pathogen pressures would evolve to increase potential AMP production, while species whose ecologies involve less exposure to pathogens would be expected to reduce their AMP complement. The gene discussed is ADSL; the disease is infection.