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Disruption of habitat connectivity alters host movement patterns and pathogen exposure in wildlife. Changes in exposure dynamics have led to increased research interest in host-associated microbial communities (i.e., microbiomes), particularly in how repeated encounters with pathogens may drive microbial filtering processes that favor the assembly of pathogen-inhibiting microbiomes, a concept known as the adaptive microbiome principle. Understanding how habitat connectivity and pathogen exposure shape adaptive microbiomes remains a key frontier in disease ecology. For widely distributed waterborne pathogens such as the amphibian chytrid fungusBatrachochytrium dendrobatidis(Bd), sustained host exposure in contiguous terrestrial–aquatic habitats may promote selection of microbiomes with enhanced antifungal properties. In contrast, under conditions of high habitat split, where key habitats such as forests and water bodies are spatially disconnected, limited exposure to Bd during the pre-breeding and overwintering seasons may hinder the selection of Bd-inhibitory microbiomes that are critical for host protection during the subsequent breeding season, when pathogen exposure in water bodies is at its peak. Our results demonstrate that habitat split may limit recruitment of putative Bd-inhibitory skin bacteria, while Bd loads increase with habitat split for certain amphibian species. Results from Joint Species Distribution Models also indicate that habitat split is a key driver of reduced skin bacterial diversity, even after accounting for biotic and abiotic metrics. Our study provides evidence that spatial connectivity among natural habitats is essential for maintaining multiple levels of biodiversity, from host species to their associated functional microbiomes, highlighting a critical link between environmental disturbance, microbial defenses, and disease dynamics.
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Metabarcoding Approaches in Amphibian Disease Ecology: Disentangling the Functional Contributions of Skin Bacteria on Disease Outcome
Abstract Molecular technologies have revolutionized the field of wildlife disease ecology, allowing the detection of outbreaks, novel pathogens, and invasive strains. In particular, metabarcoding approaches, defined here as tools used to amplify and sequence universal barcodes from a single sample (e.g., 16S rRNA for bacteria, ITS for fungi, 18S rRNA for eukaryotes), are expanding our traditional view of host–pathogen dynamics by integrating microbial interactions that modulate disease outcome. Here, I provide an analysis from the perspective of the field of amphibian disease ecology, where the emergence of multi-host pathogens has caused global declines and species extinctions. I reanalyzed an experimental mesocosm dataset to infer the functional profiles of the skin microbiomes of coqui frogs (Eleutherodactylus coqui), an amphibian species that is consistently found infected with the fungal pathogen Batrachochytrium dendrobatidis and has high turnover of skin bacteria driven by seasonal shifts. I found that the metabolic activities of microbiomes operate at different capacities depending on the season. Global enrichment of predicted functions was more prominent during the warm-wet season, indicating that microbiomes during the cool-dry season were either depauperate, resistant to new bacterial colonization, or that their functional space was more saturated. These findings suggest important avenues to investigate how microbes regulate population growth and contribute to host physiological processes. Overall, this study highlights the current challenges and future opportunities in the application of metabarcoding to investigate the causes and consequences of disease in wild systems.
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- PAR ID:
- 10341521
- Date Published:
- Journal Name:
- Integrative and Comparative Biology
- ISSN:
- 1540-7063
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/icb/icac062
