Asexual and sexual versions of the same fungus have been living side-by-side for decades without one ever wiping the other out.
April 26, 2026
Original Paper
Long-lasting coexistence of multiple asexual lineages alongside their sexual counterparts in a fungal plant pathogen
bioRxiv · 2025.03.28.645883
The Takeaway
Biology textbooks usually teach that if two versions of a species occupy the same niche, the more efficient one will win. In the case of poplar rust fungus, asexual lineages have coexisted with their sexual relatives in the same forest for over 30 years. This contradicts the theory that sexual reproduction is always an evolutionary advantage for survival. These two groups are not geographically separated but are actively competing for the same resources. This discovery suggests that diversity can be maintained in nature much longer than current mathematical models predict.
From the abstract
Sexual-to-asexual transitions within species are crucial for understanding reproductive evolution, yet the coexistence of both modes of fungal species in the same environment is poorly documented. Here, we report this transition in a plant pathogen species that coexists within the same geographical environment. Our biological model is the poplar rust fungus Melampsora larici-populina, which displays a complex life cycle typical of rust fungi (Pucciniales). It alternates between two unrelated hos