Niche differentiation within a cryptic pathogen complex: climatic drivers and hyperparasitism at multiple spatial scales

Abstract

Pathogens are embedded in multi‐trophic food webs, which often include co‐occurring cryptic species within the same pathogen complex. Nonetheless, we still lack an understanding of what dimensions of the ecological niche might allow these cryptic species to coexist. We explored the role of climate, host characteristics (tree autumn phenology) and attack by the fungal hyperparasite Ampelomyces (a group of fungi attacking plant pathogens) in defining the niches of three powdery mildew species (Erysiphe alphitoides, E. hypophylla and E. quercicola) within a cryptic pathogen complex on the pedunculate oak Quercus robur at the continental (Europe), national (Sweden and France) and landscape scales (a 5 km2 island in southwestern Finland). Previous studies have shown that climate separated the niches of three powdery mildew species (E. alphitoides, E. hypophylla and E. quercicola) in Europe and two species (E. alphitoides and E. quercicola) in France. In our study, we did not detect a significant relationship between temperature or precipitation and the distribution of E. alphitoides and E. hypophylla present in Sweden, while at the landscape scale, temperature, but not relative humidity, negatively affected disease incidence of E. alphitoides in an exceptionally warm year. Tree variation in autumn phenology did not influence disease incidence of powdery mildew species, and hyperparasite presence did not differ among powdery mildew species at the continental, national and landscape scale. Climate did not affect the distribution of the hyperparasite at the continental scale and at the national scale in Sweden. However, climate affected the hyperparasite distribution in France, with a negative relationship between non‐growing season temperature and presence of the hyperparasite. Overall, our findings, in combination with earlier evidence, suggest that climatic factors are more important than species interactions in defining the niches of cryptic species within a pathogen complex on oak.

Beyond Nuclear Ribosomal DNA Sequences: Evolution, Taxonomy, and Closest Known Saprobic Relatives of Powdery Mildew Fungi (Erysiphaceae) Inferred From Their First Comprehensive Genome-Scale Phylogenetic Analyses

“…Others are known from many, only distantly related plants (e.g., Meeboon and Takamatsu, 2016 ; Braun et al, 2019 ; Kiss and Vaghefi, 2021 ; Young and Kiss, 2021 ). Finally, some host plants can be infected by more than one powdery mildew species, which sometimes belong to different genera (e.g., Takamatsu et al, 2007 ; Kiss et al, 2008 ; Desprez-Loustau et al, 2018 ; Kelly et al, 2021 ; Faticov et al, 2022 ). Some species have become invasive in different parts of the world ( Kiss, 2005 ; Desprez-Loustau et al, 2010 ; Kiss et al, 2020 ).…”

Impact of climate on a host–hyperparasite interaction on Arabica coffee in its native range

“…In the only other study on the effect of climate on plant pathogen–fungal hyperparasite interactions, Faticov et al. (2022) found evidence for niche differentiation between two of three cryptic powdery mildew species and their hyperparasite on the pedunculate oak at the European scale, with evidence for the hyperparasite being favoured by low temperatures during the winter in France. We also found a strong relationship between hyperparasite severity and resource availability (i.e.…”

Connecting the multiple dimensions of global soil fungal diversity

“…7°to 13°C (i.e., optimal for most plants and ectotherms and fungal pathogens' primary hosts) while sharply declining outside this range (i.e., in extreme hyper-arid, alpine, and Arctic habitats). These findings, summarizing the variety of relationships between pathogen diversity and host community properties (36)(37)(38)(39), suggest that a biotic community exceeding a certain low threshold of diversity or biomass invariably shelters a relatively diverse community of fungal pathogens.…”