Biogeography of ITS Variation in the <i>Helenium autumnale</i> (Asteraceae) Species Complex
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Bibliographic record
Abstract
Abstract— We used ITS sequences as species barcodes to evaluate 127 samples of 12 Helenium species from the eastern and central USA, focusing on a species complex of H. autumnale (76 sequences from 11 U.S. states and two Canadian provinces), the federally “threatened” H. virginicum , now recommended for delisting (30 sequences from three U.S. states), and H. flexuosum (11 sequences from four U.S. states). ITS sequences confirmed most species identifications and supported the presence of the first population of the “threatened” endemic Missouri-Virginia disjunct, Helenium virginicum , in Indiana. Because the Indiana plants grow in a restored wetland, have a cpDNA haplotype previously known only from Missouri, with a morphology similar to Missouri variants, and an herbarium search for additional populations in Indiana found none, it is unclear whether the Indiana population is natural or planted. The presence of a putative sister lineage to H. virginicum thought to exist on the Bruce Peninsula, Ontario, Canada, was not supported after sequencing 36 plants with the sister morphology that grew there along 18 km of beach fens and finding they had H. autumnale sequences. Fine-scale biogeographic patterns of intraspecific sequence variation were found mostly in H. autumnale , with centers of different base site polymorphisms found in northern North America and the Missouri Ozarks. As in a previous study, we found DNA evidence of hybridization between Helenium species in Missouri. We offer hypotheses to explain the biogeography of North American Helenium , focusing on the three species that compose the H. autumnale species complex and suggesting that H. autumnale may be a compilospecies showing incomplete lineage sorting. We encourage exploration of more Helenium species and their conspecific populations in search of fine-scale ITS base site polymorphisms to reveal emerging lineages and resolve the origins and evolutionary implications of these biogeographic patterns.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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 it