Global patterns of diversity and distribution in Aspergillus fungi are driven by human and environmental influences.

Abstract

Aspergillus fungi are key producers of pharmaceuticals, enzymes, and food products and exhibit diverse lifestyles, from saprophytes to opportunistic pathogens. The genus is divided into 28 taxonomic sections sharing traits (e.g., natural products) and lifestyles (e.g., xerophily, pathogenicity). Understanding global patterns of Aspergillus occurrence and diversity would deepen our ecological understanding and help monitor pathogens and producers of mycotoxins and diverse natural products. To identify key environmental factors influencing their geographic distributions and estimate the impact of future climate change, we trained a random forest machine learning classifier on 19,105 terrestrial occurrence records for 27 taxonomic sections and 96 environmental variables to predict distributions of each section. We found that regions with high section diversity are concentrated in temperate forests, suggesting that areas with mild seasonal variation serve as diversity hotspots. Section range estimates revealed extensive variability, and low range overlap suggests distinct niches. The top predictors of average section richness were the index of cumulative human impact, ecosystem productivity, and forested vs. non-forested ecoregions. Our future climate analyses revealed considerable variation in section range estimates in response to changing climates. Suitable habitats for some sections are predicted to expand (e.g., section Restricti) and others to contract (e.g., section Nigri) or remain stable (e.g., section Fumigati) in the next few decades. Our findings reveal that both natural and human factors influence the macroecology of Aspergillus fungi and highlight their ecological diversity, including the diversity of their responses to changing climates, which is of relevance to pathogen and mycotoxin risk assessment.