Biogeography of higher Diptera in glacial and postglacial grasslands
Bibliographic record
Abstract
The presence of xeric grasslands on south-facing slopes in the Yukon Territory, Canada, has not been definitively explained. There are two competing hypotheses to explain their presence beyond the usual southern range of grasslands: (1) they are relicts of the Pleistocene mammoth steppe, widespread during the last glacial in Beringia, (2) they are relicts of the expansion of southern grasslands during the Hypsithermal, the warmest period of this last interglacial.This thesis examines the biogeographical patterns of selected acalyptrate Diptera in Canadian glacial and postglacial grasslands, with emphasis on the persistence of Yukon grasslands in an otherwise boreal zone. Flies were studied from three regions: the southern Prairies (AB and MB), the Peace River region (AB) and the southern Yukon. The Peace River grasslands were used as a baseline of a community influenced by a Hypsithermal expansion. Community structure, at the species-level, of the family Chloropidae was compared across the three grassland regions. Additionally, phylogeographic patterns at the population level were studied in three species: Incertella incerta (Becker), Meromyza columbi Fedoseeva (Chloropidae) and Trixoscelis fumipennis Melander (Heleomyzidae). Over 11,000 Chloropidae were used in the species-level analysis, representing 96 species. The community structure of the Chloropidae from Yukon grasslands was distinct from the community structure of southern grassland Chloropidae, including those from the Peace River region.At the population level, two genes were analysed: cytochrome c oxidase subunit I and cytochrome b. For all three species, almost all haplotypes from the Yukon were unique, the Yukon individuals formed separate genetic lineages from the two southern regions and divergence times between the Yukon and southern populations suggested that populations diverged during the Pleistocene, prior to the end of the Wisconsinan glaciation.Biogeographical analyses at both levels suggest that modern Diptera communities in Yukon xeric grasslands survived Pleistocene glaciations in Beringia. This implies that these Yukon boreal grasslands are not recent expansions of southern grasslands but are rather relicts of the Pleistocene mammoth steppe which was widespread in Beringia during the last ice age.
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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 | 0.000 |
| 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".