Maintaining connections between natural habitats may support beneficial microbes that help wildlife defend against disease. In a new study of tropical amphibians, a team led by Penn State biologists found that amphibians in connected natural forests and aquatic habitats were more likely to host beneficial skin microbes that inhibit a deadly fungal pathogen. But when these habitats become spatially separated due to planted crops, infrastructure development or other human land use, those microbial defenses weaken and pathogen infection levels can increase with potentially deadly results.