Living on the edge: Pleistocene ice‐free refugia and collared lemming ( <i>Dicrostonyx</i> sp.) in the North American High Arctic
Bibliographic record
Abstract
Collared lemmings (genus Dicrostonyx ) are an emblematic group of Arctic‐tundra mammalian communities, comprising six different species in North America. As other northern fauna, most of their diversity is impacted by Pleistocene glacial–interglacial cycles. While D. hudsonius and D. richardsoni have a restricted distribution area on both sides of the Hudson Bay, D. groenlandicus is widespread in all Nearctic northernmost regions, from Alaska and Canadian mainland to the High Arctic Archipelago and Greenland, occupying a highly fragmented area. Using extensive data, this paper investigates the morphological variability of the molar of Nearctic Dicrostonyx using geometric morphometrics. Our results show weak interspecific differences among Nearctic Dicrostonyx , while demonstrating the existence of a clear geographical structure: a north–south gradient that structures collared lemming's phenotype, surpassing interspecific differences. The possible causes of such patterns are explored, whether they are environmental (e.g. due to local to regional climatic conditions) or phylogeographic (e.g. isolation of the populations during the glacial periods) using ERA5‐Land reconstruction climatic data, and a reconstruction of the Laurentide Ice Sheet extent with isometric variations. The peculiar status of several populations, including Greenland and Victoria Island specimens, can be linked with their survival and isolation in Pleistocene ice‐free refugia in the High Arctic in agreement with both genetic and morphological signals. We argue that studying present‐day morphological variability can provide meaningful information on the Quaternary biogeography of modern species.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| 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 teacher head, 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".