EVOLUTIONARY GENETICS AND PLEISTOCENE BIOGEOGRAPHY OF NORTH AMERICAN TREE SQUIRRELS (TAMIASCIURUS)
Bibliographic record
Abstract
Abstract Nucleotide sequence data from the mitochondrial DNA (mtDNA) cytochrome-b gene and allozymic data were used to infer the evolutionary and biogeographic histories of New World tree squirrels of the genus Tamiasciurus. Phylogenetic analyses of the cytochrome-b data support the existence of 3 mtDNA lineages within Tamiasciurus: a western lineage consisting of populations of T. douglasii from western British Columbia (Canada), Washington, Oregon, and California, and T. mearnsi from northern Baja California (Mexico); a southwestern lineage consisting of populations of T. hudsonicus from New Mexico and Arizona; and a geographically widespread lineage comprising populations of T. hudsonicus from the remainder of the species' range. Levels of mtDNA sequence variation observed within and among populations of Tamiasciurus were small (0–2.4%), suggesting that contemporary geographic patterns of genetic variation in Tamiasciurus have been established relatively recently (i.e., in the Late Pleistocene). Allozyme analyses also support a close relationship among extant populations of Tamiasciurus. No fixed allelic differences were observed among the 3 recognized species and interspecific genetic distances (Nei's D) were substantially less than those typically observed between sibling species. Although differing from the current taxonomy in several respects, geographic patterns of genetic variation observed within Tamiasciurus are similar to those observed in a variety of North American boreal forest taxa and most likely reflect effects of forest fragmentation associated with glacial cycles of the Pleistocene.
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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 | 0.000 | 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 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".