Cytogenetic comparison of Cuscuta psorothamnensis and C. veatchii (Convolvulaceae), two species originated from recurrent hybridization between the same diploid parents
Bibliographic record
Abstract
Genus Cuscuta L. (Convolvulaceae) exhibits cases of hybridization and allopolyploidy. Section Denticulatae, subg. Grammica, includes four species: the allopolyploids, C. veatchii and C. psorothamnensis (2n = 60), which originated from two independent reticulation events between the diploids, C. denticulata and C. nevadensis (2n = 30). The allopolyploids are morphologically similar, but are differing in their geographical distribution and host specificity. While cytogenetic data have been reported for C. veatchii, this study aims to provide a comparative analysis with C. psorothamnensis. To characterize the chromosomal complement of C. psorothamnensis and compare it with C. veatchii, we used CMA/DAPI banding, FISH, and GISH. The karyotypes of both species displayed similarity in chromosome number, size, and symmetry, and interphase nucleus organization. Both species exhibited a pair of 5S and 35S rDNA sites adjacent on the same chromosome. The number of 5S rDNA sites in C. psorothamnensis is variable, with some individuals displaying four, five, and six sites. Our results show: 1) the chromosomal pair carrying adjacent 5S and 35S rDNA in C. denticulata is retained in the polyploids; 2) the loss of C. nevadensis rDNA sites occurred in both tetraploids; 3) C. psorothamnensis and C. veatchii are allopolyploids part of a species complex, originated from successive independent hybridization events between C. denticulata and C. nevadensis; and 4) C. psorothamnensis is probably more recent in origin than C. veatchii based on the degree of diploidization. This cytogenetic comparison allows us to understand the processes involved in the emergence of new polyploid species by hybridization.
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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) | 0.001 | 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 | 0.001 |
| 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".