Two Basidiomycete Fungi in the Cortex of Wolf Lichens
Bibliographic record
Abstract
Since the late 1800s, mycologists have been detecting fungi above and beyond the assumed single fungus in lichen thalli [1-6]. Over the last century, these fungi have been accorded roles ranging from commensalists to pathogens. Recently, Cyphobasidiales yeasts were shown to be ubiquitous in the cortex layer of many macrolichens [7], but for most species, little is known of their cellular distribution and constancy beyond visible fruiting structures. Here, we demonstrate the occurrence of an additional and distantly related basidiomycete, Tremella, in 95% of studied thalli in a global sample of one of the most intensively studied groups of lichens, the wolf lichens (genus Letharia). Tremella species are reported from a wide range of lichen genera [8], but until now, their biology was deduced from fruiting bodies (basidiomata) formed on lichen thalli. Based on this, they have been thought to be uncommon to rare, to occur exclusively in a hyphal form, and to be parasitic on the dominant fungal partner [9, 10]. We show that, in wolf lichens, Tremella occurs as yeast cells also in thalli that lack basidiomata and infer that this is its dominant stage in nature. We further show that the hyphal stage, when present in Letharia, is in close contact with algal cells, challenging the assumption that lichen-associated Tremella species are uniformly mycoparasites. Our results suggest that extent of occurrence and cellular interactions of known fungi within lichens have historically been underestimated and raise new questions about their function in specific lichen symbioses.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".