Structure and dynamics of a natural hybrid zone between the toads «Anaxyrus americanus» and «Anaxyrus hemiophrys», in Southeastern Manitoba
Bibliographic record
Abstract
Hybrid zones are natural showcases for evolutionary processes. I studied a natural hybrid zone between two species of toads, Anaxyrus americanus and A. hemiophrys in southeastern Manitoba in order to determine the type of selection maintaining the hybrid zone and to test the applicability of the leading descriptive models. I mapped the cline between the two species based on data from morphological measurements, allozyme frequencies and DNA sequences. I also mapped the transition in habitat from one end of the zone to the other based on the extent of forest cover portrayed on topographical maps. The position of the cline centre was determined with maximum likelihood methods, and the coincidence of the clines in particular characters was evaluated with likelihood ratio tests. The history that I documented of back-and-forth movement of the morphological cline independent of the position of the habitat transition indicates the importance of endogenous selection as expected in "tension" zones. However, the general lack of coincidence of single-character clines, based on analysis of molecular data and allozymes, reveals that exogenous selection is the more likely explanation for this hybrid zone's maintenance. Thus, the bounded hybrid superiority model would best describe this particular hybrid zone.
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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 | 0.000 |
| 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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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 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".