Are novel or locally adapted pathogens more devastating and why? Resolving opposing hypotheses.

Area of Science:

• Ecology
• Pathogen biology
• Conservation science

Background:

• Pathogens often adapt to local hosts, yet novel pathogens can threaten biodiversity and public health.
• Understanding host-pathogen dynamics is crucial for predicting disease spread and impact.

Purpose of the Study:

• To test if novel host-pathogen interactions, despite common local adaptation, pose substantial risks.
• To quantify the variance in outcomes of novel host-pathogen interactions.

Main Methods:

• A continental-scale common garden experiment was conducted using Batrachochytrium dendrobatidis and various amphibian hosts.
• A global-scale meta-analysis was performed to assess host-pathogen outcomes across different geographic and phylogenetic distances.

Main Results:

• Local amphibian-fungal interactions showed higher pathogen prevalence, growth, and host mortality.
• Novel host-pathogen interactions exhibited variable consequences, including highly virulent combinations.
• Most pathogen introductions were benign, but a significant variance in outcomes exists.

Conclusions:

• Moving organisms globally increases the risk of pathogen introductions with potentially profound harm.
• The variance in novel host-pathogen outcomes underscores the risk associated with biological invasions.