Are Toad-Headed Lizards Phrynocephalus przewalskii and P. frontalis (Family Agamidae) the Same Species? Defining Species Boundaries with Morphological and Molecular Data
Bibliographic record
Abstract
Toad-headed lizards of the Phrynocephalus przewalskii complex provide a challenging case for delimiting species boundaries. We tested the species status of P. przewalskii and P. frontalis using mitochondrial DNA (mtDNA) sequence and morphological data. A phylogenetic analysis was applied to the mtDNA data and principal component analysis (PCA) was applied to the morphological data. Furthermore, Mantel tests were used to test congruence between the patristic distance matrix derived from the phylogenetic tree and Euclidean distance matrix derived from PCA. The phylogenetic tree presented deeply diverged discreet clades that largely correspond to the two putative species. Nevertheless, PCA revealed no distinct clustering of individuals. Unique maternal inheritance might explain the discrete mtDNA variations while nuclear gene based morphological variations were continuous. Mantal tests suggested the mtDNA and morphology diverged in concordance; both had evidence of a west to east clinal variation. We conclude that P. frontalis is a synonym of P. przewalskii . Furthermore, the Mantel test is a useful method to compare mtDNA data with morphological data, but insufficient to delimit species boundaries.
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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 | 0.000 | 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".