Reconstructing the tempo and mode of evolution in an extinct clade of birds with ancient DNA: The giant moas of New Zealand
Bibliographic record
Abstract
The tempo and mode of evolution of the extinct giant moas of New Zealand remain obscure because the number of lineages and their divergence times cannot be estimated reliably by using fossil bone characters only. We therefore extracted ancient DNA from 125 specimens and genetically typed them for a 658-bp mtDNA control region sequence. The sequences detected 14 monophyletic lineages, 9 of which correspond to currently recognized species. One of the newly detected lineages was a genetically divergent form of Megalapteryx originally described as a separate species, two more were lineages of Pachyornis in southern and northeastern New Zealand, and two were basal lineages of South Island Dinornis. When results from genetic typing and previous molecular sexing were combined, at least 33.6% of the specimens were incorrectly classified. We used longer sequences of the control region and nine other mtDNA genes totaling 2,814 base pairs to derive a strongly supported phylogeny of the 14 moa lineages. Molecular dating estimated the most recent common ancestor of moas existed after the Oligocene drowning of New Zealand. However, a cycle of lineage-splitting occurred approximately 4-10 million years ago, when the landmass was fragmented by tectonic and mountain-building events and general cooling of the climate. These events resulted in the geographic isolation of lineages and ecological specialization. The spectacular radiation of moa lineages involved significant changes in body size, shape, and mass and provides another example of the general influence of large-scale paleoenvironmental changes on vertebrate evolutionary history.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| 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".