Bibliographic record
Abstract
The evolution of air‐breathing represents one the most pronounced changes in the cardio‐respiratory physiology of vertebrates. While a lot is known about the physiological transitions required for air‐breathing evolution, there is limited information available on the evolutionary dynamics in breathing mode. Previous analyses suggest 34–67 independently origins of air‐breathing within extant vertebrates, but nothing is known about when in geological time air‐breathing originated or if air‐breathing has been secondarily lost. This study aimed to 1) provide more robust estimates on the number of air‐breathing origins, 2) identify if air‐breathing has been secondarily lost within clades of air‐breathing fishes, and 3) identify the timing of these events. To do this, we used an updated list of air‐breathing fishes, a fully resolved, time‐calibrated fish phylogeny and Bayesian phylogenetic comparative methods. We show that air‐breathing evolved 74–80 times within extant vertebrates, which is significantly higher the previously proposed 34–67 independent origins. Further, we show strong support for 7 secondary losses of air‐breathing, where pure water‐breathing was adapted from an air‐breathing ancestor. Finally, we show that the majority of air‐breathing clades radiated within the last 65 million years. This study adds novel dimensions to the evolution of air‐breathing and identifies an unprecedented evolutionary plasticity in breathing mode, where air‐breathing has been gained and lost repeatedly during the evolutionary history of vertebrates. Support or Funding Information Christian Damsgaard is supported by the Carlsberg Foundation. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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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 | 0.002 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.003 |
| Scholarly communication | 0.002 | 0.004 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.008 | 0.002 |
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".