Positive associations matter: Microbial relationships drive tick microbiome composition.

Area of Science:

• Microbial ecology
• Vector-borne disease research
• Genomics and bioinformatics

Background:

• The blacklegged tick (Ixodes scapularis) is a primary vector for Lyme disease and other zoonotic pathogens in the U.S.
• Understanding the factors that shape tick microbiomes is crucial for predicting pathogen transmission.
• The relative importance of environmental, host, and microbial interaction factors remains unclear.

Purpose of the Study:

• To quantify the roles of environment, host, microbial associations, and dispersal in shaping the Ixodes scapularis microbiome.
• To investigate the influence of these factors on the prevalence of key pathogens like Borrelia burgdorferi.
• To generate hypotheses regarding pathogen-symbiont interactions within tick species.

Main Methods:

• Utilized complementary machine-learning approaches to analyze microbiome variation.
• Assessed the predictive power of microclimate, host factors, and bacterial co-occurrence patterns.
• Focused on the microbiome of the blacklegged tick (Ixodes scapularis).

Main Results:

• Positive microbial associations, including pathogen-symbiont interactions, were the dominant factor shaping the tick microbiome.
• Microclimate and host factors influenced specific microbes, such as Borrelia (Borreliella) and Ralstonia, but were poor predictors for most taxa at a regional scale.
• Environmental and host variables had limited predictive power for the majority of microbes in the Ixodes scapularis microbiome.

Conclusions:

• Microbial co-occurrence and interactions are the most significant drivers of the Ixodes scapularis microbiome composition.
• Pathogen-symbiont interactions within ticks warrant further investigation.
• Findings provide insights into potential responses of tick microbial communities to climate change.