Coupled evolutionary rates shape a Hawaiian insect-symbiont system
Bibliographic record
Abstract
Abstract Background The Hawaiian Pariaconus psyllid radiation represents a unique system to study the co-evolution of nuclear, mitochondrial, and endosymbiont genomes. These psyllids, which diversified across the Hawaiian Islands during the last 3–3.5 million years vary with their ecological niches on their plant host ‘Ōhi’a lehua (Metrosideros polymorpha) (free-living, open-gall, and closed-gall lifestyles) and harbor one to three beneficial bacterial endosymbionts. Co-evolutionary studies of other multi-endosymbiont insect systems have shown decoupled rates of sequence evolution between mitochondria and endosymbionts. Here we examine the evolutionary trends in Pariaconus psyllids, their mitochondria and their endosymbionts to determine if they fit this paradigm. Results We sequenced a new Carsonella genome from the ohialoha species group (closed-gall, one symbiont), revealing a remarkable degree of gene conservation between two of the most divergent species from this diverse species group that has dispersed across multiple islands. Further, despite the rapid radiation of psyllid species, we observed complete synteny among mitochondrial genomes from all six Pariaconus species in this study, suggesting the preservation of genome structure due to strong purifying selection. Phylogenetic analyses of the nuclear, mitochondrial, and endosymbiont genomes across these six Pariaconus species revealed correlated rates of substitutions, contrary to prior reports of decoupling between mitochondrial and endosymbiont genomes in other insect systems with multiple symbiont partners. Finally, we found that free-living psyllids with three symbionts exhibited elevated mutation rates (~ 1.2–1.6x) across all genomes and elevated rates of fixation of nonsynonymous substitutions in the insect nuclear genome and one of the endosymbionts. Conclusions This study highlights the interplay between ecological diversification and genomic evolution in Pariaconus. Further, these data indicate that multiple endosymbiont partners alone are not sufficient to result in decoupling rates of sequence evolution. Future work on basal members of this species radiation will refine our understanding of the mechanisms shaping this dynamic insect-symbiont system and its implications for genome evolution.
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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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".