Extreme Color Variation within Populations of the Common Gartersnake, Thamnophis sirtalis, in Central North America, with Implications for Subspecies Status
Bibliographic record
Abstract
We report on the remarkable variation and frequency of color morphs within and among eight populations of the Common Gartersnake (Thamnophis sirtalis) in central Manitoba, Canada and one on Isle Royale, Michigan, USA. Five color morph categories are identified, one melanistic and four scored on a qualitative scale based on expression of red pigment. In the most northern population (Jenpeg, 54.464°N, 98.115°W) and two island populations (George Island, Lake Winnipeg, 52.819°N, 97.620°W; Isle Royale, 48.102°N, 88.601°W), all five color morphs were expressed. The northernmost population also exhibited sexual color dimorphism, with female snakes expressing significantly more red than males. In contrast, two central and western populations showed very little variation, with only two of the most similar color morphs present. We provide the first report of erythristic snakes in Manitoba, found in three separate locations around Lake Winnipeg. Melanistic snakes are also reported from three new localities in the province, all widely disjunct from previously identified sites around Lake Winnipegosis. Manitoban and Isle Royale populations are compared with color frequency data from sites in mainland Michigan and in Kansas. Color patterns among populations do not follow traditionally recognized zones of intergradation between T. s. parietalis and T. s. sirtalis. The extreme intrapopulational variation suggests that subspecies of T. sirtalis based on color are of questionable validity.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".