Abstract:

Background & Aims: Understanding how species coexist is a core question in community ecology that has long intrigued ecologists. Under the contemporary coexistence theory, the mechanisms that promote species coexistence are categorized into stabilizing and equalizing mechanisms. However, we know little about how foliar fungal pathogens affect stabilizing and equalizing mechanisms, despite being abundant and important.

Progresses & Challenges: In this review, we briefly introduce the experimental evidence of how foliar fungal diseases promote plant species coexistence through conspecific negative density dependence (via stabilizing mechanisms) and growth-defense tradeoffs (via equalizing mechanisms), as well as how community-level foliar fungal pathogen removal affects plant species richness. We then discuss controversies surrounding this topic. These controversies mainly focused on the relative importance of foliar fungal pathogens in driving species coexistence compared to other factors, host specificity of foliar fungal pathogens, and methodological issues in related studies.

Prospects: We highlight some open questions for future studies on this topic, including how climate change and soil nutrients affect the relationship between foliar fungal pathogens and species coexistence, the interactions between foliar fungal pathogens and other high trophic biomes impact upon species coexistence, inferring the effects of foliar fungal pathogens on plant community assembly based on phylogeny, and incorporating plant life histories into related studies.

Key words: species coexistence, species diversity, foliar fungal pathogens, negative density dependence, stabilizing mechanisms, equalizing mechanisms