Range-wide genetic structure of maritime pine predates the last glacial maximum: evidence from nuclear DNA
Bibliographic record
Abstract
Using nuclear simple sequence repeats (nuSSRs), we determined the genetic variability in the natural distribution range of maritime pine (Pinus pinaster) in the western Mediterranean region. We analysed the role of global and significant climatic fluctuations in driving the evolutionary diversification of this species. We attempted to determine the impact of the last glacial maximum (LGM) and human activity on genetic variation and to identify the effect of bottlenecks, admixing, migration, time to the most recent common ancestor (TMRCA), and recent splits. A total of 972 individuals were analysed. The sample represented 27 natural populations from the western Mediterranean region, which encompasses most of the natural range of P. pinaster. Using eight nuSSRs, we analysed genetic diversity indices for each population and group of populations. We also examined the interpopulation structure by the frequency and distance method and investigated genetic barriers, signals of historical demographic fluctuations, phylogeographic structure, admixing, rate of mutation, migration, as well as testing the hypothesis of isolation by distance (IBD). Both cluster analyses showed similar population genetic structure with three genetic barriers that divided the samples into four large groups. Intensive migration was only detected during the period of the last glacial maximum (LGM), which permitted the mutation rate of the markers used to be calculated. The majority of the population was found to exhibit signs of a recent bottleneck and its timing showed a clear northeast-southwest geographic distribution. A clearly defined phylogeographic structure (Nst > Gst and Rst > Gst ) under IBD was established, and showed the highest divergence between groups of populations separated by physical barriers, such as the Strait of Gibraltar, the Mediterranean Sea and the Pyrenees. The high level of intergroup genetic differentiation (ΦIS = 20.26) was attributed to a long historical isolation (which occurred before the last 18 000 years) between the principal maritime pine population groups that occurred due to physical barriers that limited pollen and seed transfer, combined with a minimal effective radius of distribution. The low level of genetic diversity among the populations was combined with genetic drift and a recent bottleneck during the period of human activity. Significant migration across barriers was due to spontaneous phenomena during the LGM, which had no significant impact on the genetic structure owing to its relatively short duration and the fragmented species. The phylogeographic structure under the assumption of IBD was well established for P. pinaster in each of the principal population groups.
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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) | 0.001 | 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".