Chromosomal evolution and evidence of a putative multiple sex chromosome system in the Amazonian northeastern pepper frog (<i>Leptodactylus vastus</i>, Lutz 1930)
Bibliographic record
Abstract
The genus Leptodactylus is among the most studied anurans in cytogenetics. Despite exhibiting chromosomal conservatism with 2n = 22, microstructural studies (here defined as investigations of subchromosomal features such as DNA repetitive elements, chromatin organization, and sequence-level structural arrangements) have revealed significant karyotypic diversity within the genus, primarily associated with the distribution of repetitive sequences. Additionally, complex sex chromosome systems have been identified, underscoring the importance of further studies on these species. In this context, we performed a karyotypic characterization of Leptodactylus vastus from the Amazonian region. Using conventional cytogenetics, FISH with repetitive sequences, and phylogenetic analyses, we identified extensive chromosomal rearrangements, evidenced by the distribution of heterochromatin and repetitive sequences, including microsatellites, 18S rDNA, and U2 snDNA. Meiotic analyses in males revealed the presence of multivalent chromosomal chains involving eight chromosomes, a pattern consistent with a multiple sex chromosome system (X1Y1X2Y2X3Y3X4Y4). Concerning the clusters of repetitive sequences, we observed in specific chromosome pairs underscores the potential cytotaxonomic relevance of these markers. Phylogenetically, Leptodactylus vastus belongs to the Leptodactylus pentadactylus group, which includes other species known to possess multiple sex chromosome systems, although the absence of female data prevents definitive confirmation of this system in this species. Our results suggest that chromosomal rearrangements may have contributed to the genomic diversification of the species, supporting previous hypotheses on the role of structural variation in Leptodactylus species while highlighting the need for further comparative studies involving both sexes to fully clarify the nature of the multivalent chromosomal chains observed in Leptodactylus vastus.
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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".