Adaptation during the transition from <i>Ophiocordyceps</i> entomopathogen to insect associate is accompanied by gene loss and intensified selection
Bibliographic record
Abstract
Abstract Fungal and bacterial symbiosis is an important adaptation that has occurred within many insect species, which usually results in the relaxation of selection across the symbiont genome. However, the evolutionary pressures and genomic consequences associated with this transition are not well understood. Pathogenic fungi of the genus Ophiocordyceps have undergone multiple, independent transitions from pathogen to associate, infecting soft-scale insects trans-generationally without killing them. To gain an understanding of the genomic adaptations underlying this transition, long-read sequencing was utilized to assemble the genomes of both Parthenolecanium corni and its Ophiocordyceps associate from a single insect. A highly contiguous haploid assembly was obtained for Part. corni , representing the first assembly from a single Coccoidea insect, in which 97% of its 227.8 Mb genome was contained within 24 contigs. Metagenomic-based binning produced a chromosome-level genome for Part. corni ’s Ophiocordyceps associate. The associate genome contained 524 gene loss events compared to free-living pathogenic Ophiocordyceps relatives, with predicted roles in hyphal growth, cell wall integrity, metabolism, gene regulation and toxin production. Contrasting patterns of selection were observed between the nuclear and mitochondrial genomes specific to the associate lineage. Intensified selection was most frequently observed across nuclear orthologs, while selection on mitochondrial genes was found to be relaxed. Furthermore, scans for diversifying selection identified associate specific selection within three adjacent enzymes catalyzing acetoacetate’s metabolism to acetyl-COA. This work provides insight into the adaptive landscape during the transition to an associate life history, along with a base for future research into the genomic mechanisms underpinning the evolution of Ophiocordyceps .
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".