Demographic history and genetic differentiation of an endemic and endangered Ulmus lamellosa (Ulmus)
Bibliographic record
Abstract
BACKGROUND: Ulmus lamellosa (one of the ancient species of Ulmus) is an endemic and endangered plant that has undergone climatic oscillations and geographical changes. The elucidation of its demographic history and genetic differentiation is critical for understanding the evolutionary process and ecological adaption to forests in Northern China. RESULTS: Polymorphic haplotypes were detected in most populations of U. lamellosa via DNA sequencing. All haplotypes were divided into three phylogeographic clades fundamentally corresponding to their geographical distribution, namely THM (Taihang Mountains), YM (Yinshan Mountains), and YSM (Yanshan Mountains) groups. The YSM group, which is regarded as ancestral, possessed higher genetic diversity and significant genetic variability in contrast to the YSM and YM groups. Meanwhile, the divergence time of intraspecies haplotypes occurred during the Miocene-Pliocene, which was associated with major Tertiary geological and/or climatic events. Different degrees of gene exchanges were identified between the three groups. During glaciation, the YSM and THM regions might have served as refugia for U. lamellosa. Based on ITS data, range expansion was not expected through evolutionary processes, except for the THM group. A series of mountain uplifts (e.g., Yanshan Mountains and Taihang Mountains) following the Miocene-Pliocene, and subsequently quaternary climatic oscillations in Northern China, further promoted divergence between U. lamellosa populations. CONCLUSIONS: Geographical topology and climate change in Northern China played a critical role in establishing the current phylogeographic structural patterns of U. lamellosa. These results provide important data and clues that facilitate the demographic study of tree species in Northern China.
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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 | 0.000 |
| 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) | 0.000 | 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 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".