Intergenomic interactions in unisexual salamanders of the genus Ambystoma (Amphibia, Caudata)
Bibliographic record
Abstract
North American unisexual salamanders of the genus Ambystoma are the most ancient unisexual vertebrate lineages known to exist and demonstrate an extremely flexible and complex reproductive system. To understand how this lineage has persisted for long periods of time, three important evolutionary questions need to be answered: (1) do intergenomic exchanges take place in unisexual meiosis to generate genetic diversity; (2) is genome replacement a common reproductive mechanism in unisexual populations and; (3) is there an ancient or a particular "L" genome that has persisted in various unisexual genome compositions. In this dissertation, a combination of molecular cytogenetic techniques and phylogenetic methods were used to provide conclusive answers to these three questions. Various intergenomic exchanges and other types of chromosome mutations were identified by genomic 'in situ' hybridization (GISH) and derivative techniques in unisexual populations, suggesting that genomes of unisexual 'Ambystoma' have undergone frequent and complex reconstructions. In addition, intergenomic exchanges and major rDNA cytotypes that were generated through GISH/FISH-rDNA were used to construct a genealogy of unisexual 'Ambystoma' in southern Ontario. The results suggest that current LJJ and LJJJ unisexual populations in southern Ontario were likely derived from a few unisexual females. Finally, 283 specimens throughout the range were collected and a genealogy of the "L" genomes was constructed using a nuclear DNA marker (L-G1C12). The results demonstrate that the general geographical distribution of the haplotypes in unisexual populations conformed to those found in 'A. laterale', indicating that "L" genomes in unisexuals were obtained from sympatric or nearby populations of 'A. laterale'. The data show that replacement of genomes by sexual sperm donors frequently occurs in unisexual 'Ambystoma' across their range and there is no ancient or particular "L" genome. Complex intergenomic interactions, including intergenomic exchanges and genome replacement with sexual sperm donors, could substantially increase genetic diversity and evolutionary flexibility of unisexual 'Ambystoma'. My studies demonstrate how unisexual 'Ambystoma' can incorporate "a bit of sex" and circumvent unusual reproductive mechanisms to enable long-term evolutionary sustainability, which help us understand why sexual reproduction is common and important in animals.
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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".