Repetitive DNA Dynamics, Phylogenetic Relationships and Divergence Times in Andean Ctenomys (Rodentia: Ctenomyidae)
Bibliographic record
Abstract
The genus Ctenomys comprises a group of rodents with remarkable karyotypic variability linked to the distribution of repetitive sequences and rearrangements. We analyzed the distribution and variation of repetitive DNA in two parapatric Andean species from Chile: Ctenomys maulinus brunneus (2n = 26; FNa = 48) and Ctenomys sp. (2n = 28; FNa = 50). Self-genomic in situ hybridization (Self-GISH), whole comparative genomic hybridization (W-CGH), and fluorescent in situ hybridization (FISH) using a telomeric probe were performed. Phylogenetic relationships and divergence times based on cytochrome b sequences helped infer the direction and timing of cytogenetic changes. Self-GISH revealed the absence of highly repetitive sequences in four chromosome pairs of C. m. brunneus and nine in Ctenomys sp. W-CGH showed no differential expansion of species-specific repeats, suggesting no recent major sequence turnover. FISH detected signals exclusively in telomeres. Phylogenetic analyses indicate that C. m. maulinus (2n = 26) diverged from the clade formed by C. m. brunneus and Ctenomys sp. during the Late Pleistocene, supporting, together with cytogenetic data, a loss of repetitive sequences associated with fission events from 2n = 26 to 28. These findings highlight the evolutionary significance of repetitive DNA and reinforce Ctenomys as a model for studying chromosomal evolution.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 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) | 0.001 | 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".