High Genetic Variability With No Apparent Geographic Structuring in the mtDNA of the Amphidromous River Shrimp Cryphiops caementarius (Decapoda: Palaemonidae) in Northern-Central Chile
Bibliographic record
Abstract
Freshwater organisms with an amphidromous life cycle are generally thought to disperse widely through marine planktonic larval stages, but only few studies on genetic population structure of amphidromous shrimp exist. We used a 640-basepair region of the mitochondrial gene cytochrome c oxidase I (Cox1) from the amphidromous river shrimp Cryphiops caementarius from five rivers in northern-central Chile to test whether large distances between estuaries (up to 700 km) limit gene flow between populations and result in genetic differentiation among populations. The results revealed high haplotype diversity with no significant geographical structuring, suggesting that gene flow occurs regularly over several hundreds of kilometres, also connecting populations north and south of the Atacama Desert. Seemingly, the terrestrial barrier is overcome by planktonic larval dispersal through the sea, suggesting wide dispersal rather than “stepping-stone” dispersal between estuaries. The population from the southern limit of the geographic distribution of C. caementarius (Río Limari) revealed some weak differentiation in pairwise WST comparisons, but larger sample sizes are necessary to confirm this. Additional studies are needed for a better understanding of factors that promote different life histories, like marine planktonic dispersal, larval retention in estuaries, or an amphidromous-freshwater transition towards a purely freshwater life cycle.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".