The role of interspecific hybridization in adaptive potential at range margins
Bibliographic record
Abstract
Is interspecific hybridization an ordinary part of species biology? And if so, how evolutionarily important is it? These questions have been discussed in the botanical literature, in one form or another, at least since J.P. Lotsy early in the last century. He coined the term syngameon, now defined as "a group of otherwise distinct species interconnected by limited gene exchange, i.e. the most inclusive interbreeding evolutionary unit" (Suarez-Gonzalez, Lexer, & Cronk, Biology Letters, 14, 20170688, ). North American poplars (Populus, Salicaceae) form one such syngameon. In this issue of Molecular Ecology, a new study (Chhatre, Evans, DiFazio, & Keller, Molecular Ecology, 27, ) uses three species from the North American poplar syngameon to tackle the twin issues of (a) the extent of gene exchange and (b) the significance of this gene exchange to the biology of these trees. They demonstrate that a hybrid zone exists where the ranges of Populus angustifolia and Populus balsamifera overlap in the Rocky Mountains, and postulate that this hybridization may facilitate population survival at the range edges. Indeed, the authors show that a remarkable number of loci are introgressing under selection. Very remarkably, they detect additional hybridity (making a trihybrid zone) with Populus trichocarpa (a species that does not occur in the area). Intriguingly, there is some genomic evidence of ancient introgression events. This suggests a model of episodic species divergence and hybridization, in which the syngameon is dynamic and behaving as a supraspecific metapopulation over geological time.
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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 | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.005 |
| Scholarly communication | 0.002 | 0.005 |
| Open science | 0.001 | 0.003 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 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".