Solving a century-old conundrum: genetic integrity of a rare and local endemic shrub facing introgression with a widespread congener
Bibliographic record
Abstract
Abstract Hybridization is a key driver of evolutionary processes and speciation. Advances in sequencing technology provide unprecedented opportunity to study discriminating phenotypic characters at the molecular level and identify candidate loci associated with the speciation process. Salix chlorolepis is a rare and threatened endemic shrub species restricted to the upper slopes of Mount Albert (Canada) proposed to hybridize with S. brachycarpa, a locally abundant geographically widespread congener. We aimed to characterize rangewide genetic variation of S. chlorolepis, establish whether it actually hybridizes with S. brachycarpa, and assess whether leaf pilosity is an indicative variable phenotypic trait related to introgressive hybridization. Using single nucleotide polymorphism data, we inferred patterns of genetic structure and diversity. We tested for genetic associations with environmental distance, taxonomic identity, or phenotypic variability in leaf hair density using populations genomics approaches at the multilocus (partial Mantel tests and generalized dissimilarity models) and single-locus (latent factor mixed model, pRDA, PCAdapt, OutFLANK) levels. Although a common genetic ancestry persists within S. chlorolepis, fine-scale spatial genetic structure reflects its fragmented distribution. Interspecific genetic admixture in sympatry zones corroborates the existence of introgressive hybridization. Leaf pilosity is an important variable explaining multilocus genotype variation between the two taxa. We flagged nine candidate loci that are both strongly associated with leaf pilosity phenotype and with divergent selection between taxa. The existence of such loci ‘impermeable’ to introgression ensures maintenance of interspecific barrier and clear phenotypic differentiation between species. Such genomic heterogeneity alleviates assimilation risk of the rare and threatened species by its more abundant congener despite ongoing introgression.
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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 | 0.005 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.008 |
| Scholarly communication | 0.003 | 0.005 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.002 | 0.004 |
| Insufficient payload (model declined to judge) | 0.002 | 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".