Eco-evolutionary dynamics at the altitudinal limit of a transcontinental boreal conifer
Bibliographic record
Abstract
Understanding ecological and evolutionary processes driving species range expansion is essential to assess extirpation risks and reduce future biodiversity loss. During range expansion, spatial sorting eco-evolutionary model predicts enhanced dispersal rate in leading-edge populations through local accumulation of phenotypic traits related to dispersal. This process may result in a transient trade-off, whereby local fitness is temporarily sacrificed for the benefit of dispersal during range expansion. Here, we empirically tested the spatial sorting model and its fitness cost by assessing dispersal ability of 8138 white spruce (Picea glauca) winged seeds and seed viability along altitudinal gradients in two eastern Canadian mountain ranges with different dynamics according to contrasted historical disturbance regime, as well as in a lowland site representative of the species geographical range core. In the Uapishka mountains, stand-replacing wildfires have opened the forest cover and leading-edge populations are currently expanding upslope. Dispersal ability was enhanced at the expansion front whereas germination potential decreased. Treeline populations exhibit a trade-off maximizing dispersal over fitness, as expected from the spatial sorting model. By contrast, in the McGerrigle mountains where there is no evidence of wildfire activity, treeline populations established several millennia ago and there is currently no upslope range expansion. In these mountains, no trait variation was found along the altitudinal gradient, suggesting that a local optimum was reached for the traits involved in the trade-off between dispersal ability and seed viability. In the geographical core of the range, dispersal ability reaches its lowest values while germination potential is maximal, suggesting absence of a spatial sorting mechanism, but natural selection as the primary evolutionary process operating to increase local fitness. This study sheds light on the importance of intraspecific trait variation related to the dispersal ability of individuals and its transient impact on life-history in tree populations located at the expansion front.
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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 | 0.001 | 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) | 0.000 | 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 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".