Evolutionary dynamics of a satellite DNA in the tiger beetle species pair <i>Cicindela campestris</i> and <i>C. maroccana</i>
Bibliographic record
Abstract
Satellite repeat elements are an abundant component of eukaryotic genomes, but not enough is known about their evolutionary dynamics and their involvement in karyotype and species differentiation. We report the nucleotide sequence, chromosomal localization, and evolutionary dynamics of a repetitive DNA element of the tiger beetle species pair Cicindela maroccana and Cicindela campestris. The element was detected after restriction digest of C. maroccana total genomic DNA with EcoRI as a single band and its multimers on agarose gels. Cloning and sequencing of several isolates revealed a consensus sequence of 383 bp with no internal repeat structure and no detectable similarity to any entry in GenBank. Hybridization of the satellite unit to C. maroccana mitotic and meiotic chromosomes revealed the presence of this repetitive DNA in the centromeres of all chromosomes except the Y chromosome, which exhibited only a very weak signal in its short arm. PCR-based tests for this satellite in related species revealed its presence in the sister species C. campestris, but not in other closely related species. Phylogenetic analysis of PCR products revealed well-supported clades that generally separate copies from each species. Because both species exhibit the multiple X chromosome karyotypic system common to Cicindela, but differ in their X chromosome numbers (four in C. maroccana vs. three in C. campestris), structural differences could also be investigated with regard to the position of satellites in a newly arisen X chromosome. We find the satellite in a centromeric position in all X chromosomes of C. maroccana, suggesting that the origin of the additional X chromosome involves multiple karyotypic rearrangements.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.001 | 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".