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.
The findings, published this week in the journal Proceedings of the National Academy of Sciences, reveal a previously underappreciated link between landscape connectivity, beneficial microbes and disease resistance in wildlife, according to the researchers.
"Animals rely not only on their immune systems, but also on beneficial microbes that live on their bodies and help protect them from pathogens," said Gui Becker, associate professor of biology in the Eberly College of Science at Penn State and senior author of the study. "Our results show that when natural habitats become disconnected, these microbial defenses can be disrupted."
The researchers explained that habitat loss and fragmentation are widely recognized as major drivers of biodiversity decline, but scientists are increasingly realizing that environmental change can also alter the microbiome - the community of microbes that live in and on animals and often play key roles in health and immunity.
"Our study provides evidence that connectivity among habitats is essential for maintaining multiple levels of biodiversity, from host-associated bacteria with protective functions to their respective host species," said first author Daniel Medina, previously a postdoctoral scholar in Becker's lab at Penn State and currently a lecturer in tropical forest ecology and resource management at The School for Field Studies. "It highlights a critical link between environmental disturbance, microbial defenses and disease dynamics."
