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The Early Terrestrial Fungal Lineage of Conidiobolus—Transition from Saprotroph to Parasitic Lifestyle

Summary

This research explores how certain fungi evolved from living on dead organic matter to becoming parasites of insects. The study reveals that an important fungal characteristic – the ability to forcefully shoot spores – evolved before these fungi became parasitic, rather than as an adaptation for infecting insects. This has important implications for understanding how parasitic relationships develop in nature. Impacts on everyday life: • Helps explain how beneficial insect-killing fungi evolved, which is important for biological pest control • Provides insights into the evolution of fungal diseases that can affect humans and animals • Improves our understanding of how organisms adapt to new ecological roles • Aids in developing better strategies for controlling harmful insects using natural fungal enemies • Contributes to our knowledge of biodiversity and ecosystem relationships

Background

The subphylum Entomophthoromycotina comprises over 300 species occupying various ecological niches, from saprotrophs to pathogens of insects and other organisms. Species of Conidiobolus sensu lato are saprobic or pathogenic fungi with forcibly discharged globose conidia, simple phototropic conidiophores, and secondary conidia. They have been considered a basal group in the subphylum Entomophthoromycotina, though their simple morphology has masked their phylogenetic diversity.

Objective

The study aimed to describe the lifestyle of the ancestors of conidiobolus-like fungi and determine the econiche occupied by the ancestors of Entomophthoromycotina. The researchers hypothesized that these ancestors were soil saprotrophs that evolved the ability to use dead and later living insects as substrate. A second goal was to evaluate whether forcibly discharged conidia was an adaptation to parasitic lifestyle or originated earlier evolutionarily.

Results

Phylogenetic reconstruction revealed the polyphyletic composition of Conidiobolus sensu lato, consisting of several large well-supported clades. New families were assigned including Conidiobolaceae, Capillidiaceae, Neoconidiobolaceae, and Batkoaceae. Ancestral state reconstruction showed that the ancestors were likely saprotrophic, with the ability to infect insects developing multiple times during evolution. Ballistic conidia evolved very early in Entomophthoromycotina ancestors with saprotrophic lifestyles, preceding the evolution of entomopathogenic capabilities.

Conclusion

The study demonstrates that conidiobolus-like fungi have polyphyletic origins and occupy various ecological niches ranging from saprotrophy to entomopathogenicity. Ballistic conidia evolved as an early adaptation in saprotrophic ancestors before the development of parasitic lifestyles, rather than being an adaptation specifically for insect parasitism. The research provides important taxonomic clarification and evolutionary insights for this diverse fungal group.
  • Published in:Journal of Fungi,
  • Study Type:Phylogenetic Analysis,
  • Source: 10.3390/jof8080789
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