Natural hybridization between <i>Calanus finmarchicus</i> and <i>C. glacialis</i> (Copepoda) in the Arctic and Northwest Atlantic
Bibliographic record
Abstract
Calanus glacialis and Calanus finmarchicus dominate the zooplankton community in the Arctic and North Atlantic, respectively. The vast zone of sympatry between these species, the potential for overlap between reproductive seasons, and the evidence for intermediate values of discriminant traits suggest that these species hybridize. We genotyped 684 individuals from 14 Arctic to Atlantic stations using one mitochondrial (16S) and 10 nuclear loci (microsatellites). Strong genetic differentiation between parental species confidently identified hybrids in areas of sympatry. Hybrid frequency was highly variable among stations and did not covary with mean annual sea surface temperature. In the St. Lawrence Estuary, parental and hybrid genotypes were nonrandomly distributed between depth layers (300–100 m and 100–0 m) and across sampling dates, and hybrids seemed more frequent in July than in May and September. Overall, the bimodal frequency distribution of parental and hybrid genotypes suggests that reproductive barriers limit gene flow between these species. The opportunity for interbreeding is more likely restricted by differences in species reproductive phenology than by dispersal. Hybridization also affects prosome length, a morphological trait widely used to discriminate Calanus species, and thus possibly contributes to species misidentification. Highly introgressed individuals indicate that hybrids are fertile and reproduce, suggesting that hybrid fitness could affect estimates and models of these species population dynamics. This is the first evidence for interspecific hybridization between marine zooplankton species, but similar cases could be uncovered using nuclear genetic markers in groups of closely related and morphologically similar marine zooplankton species.
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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 | 0.000 | 0.000 |
| 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 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".