Evaluation of pre‐ and post‐zygotic mating barriers, hybrid fitness and phylogenetic relationship between <i>Cyprinodon variegatus variegatus</i> and <i>Cyprinodon variegatus hubbsi</i> (Cyprinodontiformes, Teleostei)
Bibliographic record
Abstract
The euryhaline fish Cyprinodon variegatus variegatus (Cvv) is capable of tolerating ambient salinities ranging from 0.3 to 167 g l(-1) , but incapable of long-term survival in freshwater (< 2 mM Na(+) ). However, a population of this species, now designated as a subspecies (Cyprinodon variegatus hubbsi; Cvh), has been isolated in several freshwater (0.4-1 mM Na(+) ) lakes in central Florida for the past ~150 ky. We previously demonstrated that Cvh has a significantly higher affinity for Na(+) uptake suggesting that it has adapted to its dilute freshwater environment. We here evaluate whether Cvh should be considered a separate species by characterizing pre- and post-zygotic isolation, Na(+) transport characteristics of the two populations and their hybrids, and developing a molecular phylogeny of Cvv and Cvh populations in Florida using mtDNA sequence data. We found evidence of partial prezygotic isolation with Cvv females mating almost exclusively (89%) with con-specific males in choice mating experiments. Partial post-zygotic isolation was also observed with significant (59-89%) reductions in hatching success of hybrid embryos compared with con-specific embryos. Na(+) uptake kinetics in hybrids (both Cvv x Cvh and Cvh x Cvv) bred and raised under common garden conditions were intermediate to Cvh (high affinity) and Cvv (low affinity) indicating that observed differences are genetically based. Similar observations were made with respect to short-term (96 h) survival of juveniles acutely transferred from 7 mM Na(+) to a range of more dilute (0.1-2 mM Na(+) ) freshwater. Finally, although phylogenetic analysis of Cvv and Cvh populations using mtDNA sequence for ND2 were unable to fully resolve a polytomy between Cvh and Cvv populations from northeastern Florida, these data do not falsify the hypothesis that Cvh is of monophyletic origin. Overall, the available data suggest that Cvh should be considered a separate species or at a minimum an evolutionarily significant unit.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".