The Allopolyploid Origin and Population Genetics of the Rare <i>Solidago Houghtonii</i> (Asteraceae)
Bibliographic record
Abstract
Solidago houghtonii is a federally threatened hexaploid plant species of likely hybrid origin, limited geographic distribution, and high habitat specificity. An understanding of the evolutionary history and population genetic structure of rare species is critical to ensuring their long-term survival. To study the hybrid origin of S. houghtonii I sequenced four noncoding chloroplast (cp) DNA loci, and the nuclear ribosomal DNA ITS and 3' ETS regions from four individuals of S. houghtonii, which span its geographic range, and 25 other species of Solidago including all sympatric species. Polymorphisms within the nrDNA sequences indicated the presence of multiple homeologue types which were separated by molecular cloning. Phylogenetic analyses of cloned sequence data indicated that S. riddellii, S. ptarmicoides, and S. ohioensis are parents of S. houghtonii, however cpDNA sequence data indicated a fourth species, S. gigantea, as the maternal genome donor. These data reveal both a single origin and a complex pattern of reticulation that is consistent not only with the hypothesized allohexaploid nature of this species, but also with chloroplast capture of cpDNA from an unexpected source through introgression.\nThe amount of genetic diversity and the degree of population subdivision was analyzed in 23 S. houghtonii populations spanning the geographical range and habitat specificities of the species. 452 individual plants were characterized for cpDNA haplotype by screening amplicons of three noncoding cpDNA regions for length polymorphism. A total of 14 haplotypes were detected. Gene diversity (HE) across populations ranged from 0.00 - 0.59 and a high degree of population structure was found (FST = 0.76). An AMOVA partitioned most of the variation among populations (76%), and the remainder among individuals within populations (24%). Similar structure was found when the populations were grouped according to either geographic region or substrate type. A Mantel test found significant isolation-bydistance between all populations except the most disjunct population (P = 0.003). A statistical parsimony network analysis of the 14 5. houghtonii haplotypes indicated a northern Michigan origin for the species. The genetic structure of S. houghtonii populations is consistent with postglacial range expansion and contraction during the hypsithermal period ~6000YBP
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".