Phylogeography of eastern leatherwood (Dirca palustris L.) resolved by chloroplast sequencing and microsatellite genotyping
Bibliographic record
Abstract
The broad distribution of eastern leatherwood (Dirca palustris L.), from Florida to Canada, contrasted with its patchy restriction to rich, mesic forests and the paucity of vectors for dispersal of its seeds, represents a classic example of Reid's paradox of plant migration. It long has been presumed that temperate forest species of eastern North America persisted in southern glacial refugia near the Gulf Coast, after which many dispersed nearly 2000 km to contemporary northern range limits. The rates of migration necessary to account for present distributions exceed those suggested by contemporary observations of seed dispersal. I used ecological niche modeling, chloroplast sequencing, microsatellite genotyping, and phenotypic investigations to answer questions about the historical and contemporary distribution of populations and genes of D. palustris across the landscape of eastern North America. Ecological niche modeling supported my hypothesis that D. palustris persisted within mid-latitudinal refugia during the Last Glacial Maximum, and the distribution of chloroplast haplotypes supported the prehistoric presence of individuals at such latitudes. Deep diversification of chloroplast haplotypes indicated a complex history of population isolation, migration, and admixture over Pleistocene glaciations. I used next-generation sequencing for de novo isolation of highly polymorphic microsatellite loci from D. palustris. Microsatellite genetic analyses provided further evidence for mid-latitudinal refugia. Results from both markers were indicative of general dispersal limitation with instances of long-distance dispersal, especially to the Upper Midwest and Great Lakes Region; I suggest that an active vector likely was important for post-glacial range expansion of D. palustris. I provide genetic and phenotypic evidence for a new subspecies of D. palustris that is restricted in distribution to the Southeastern U.S. The putative subspecies has white pubescence on its bud scales, unlike the brown described for the species, and calyx tubes that are shorter and with wider limbs than those of D. palustris elsewhere.
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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".