Habitat fragmentation is widely recognized as a major threat to biodiversity, but its effects extend beyond the loss of habitat itself. Many species depend on multiple habitat types to complete their life cycles, and when these habitats become disconnected, movement between them becomes more difficult. For amphibians, the separation of forests from wetlands and breeding ponds can increase energetic costs, expose animals to stressful conditions, and alter interactions with pathogens.
At the same time, scientists are increasingly recognizing that an animal’s microbiome – the community of beneficial microbes living on and within its body – plays an important role in disease resistance. Understanding how habitat connectivity influences these microbial defenses is becoming an important frontier in conservation biology.
Medina, D., Martins, R.A., Prist, P.R., et al. 2026. Connecting habitats, boosting disease resistance: Spatial connectivity enhances amphibian microbiome defenses against fungal pathogen. Proceedings of the National Academy of Sciences, 123(17), p.e2520745123. DOI: 10.1073/pnas.2520745123
A new study from Brazil’s Atlantic Forest reveals that maintaining connections between habitats can help amphibians resist disease by supporting healthier skin microbiomes. Researchers examined four frog and toad species across landscapes that varied in the degree of “habitat split,” a measure of how far forest habitats were separated from aquatic breeding sites. They focused on the amphibian skin microbiome because many skin bacteria can inhibit the growth of Batrachochytrium dendrobatidis (Bd), the fungal pathogen responsible for the global amphibian chytrid disease crisis.
The team sampled nearly 600 amphibians from 40 sites and analyzed both Bd infection levels and the composition of skin bacterial communities. They found that as habitat split increased, the proportion of bacteria known to inhibit Bd consistently declined across all species. Habitat split also emerged as one of the strongest factors shaping microbial community composition, often having a greater influence than forest edge effects and rivaling broader measures of habitat loss.
The consequences extended beyond the microbiome. In species that were particularly vulnerable to Bd, greater habitat split was associated with higher fungal infection loads. These findings support the idea of an “adaptive microbiome,” in which repeated exposure to environmental microbes and low levels of pathogens helps animals maintain microbial communities that provide disease protection. When forests and breeding habitats become disconnected, amphibians may lose opportunities to acquire and sustain these beneficial microbes.
The study highlights an often-overlooked benefit of landscape connectivity. Corridors and connected habitat networks do more than facilitate animal movement and gene flow. They may also help preserve the microbial partnerships that support wildlife health. By linking forests with aquatic habitats, conservation and restoration efforts could strengthen natural disease defenses and improve the long-term persistence of amphibian populations.
More broadly, the findings support the idea that habitat connectivity influences biodiversity at multiple levels, from species and populations to the microscopic communities that help animals survive. Protecting connections among habitats may therefore be an important strategy for reducing disease risk and increasing ecosystem resilience in an increasingly fragmented world.
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