Evidence for spatial niche partitioning in the ectocommensal <i>Symbion americanus</i> (Cycliophora) on its lobster host, <scp><i>Homarus americanus</i></scp> (Arthropoda, Malacostraca)
Bibliographic record
Abstract
Abstract Symbion americanus is a microscopic marine invertebrate in the phylum Cycliophora that lives as an ectocommensal on the mouthparts of the American lobster, Homarus americanus. Previous phylogeographic work on S. americanus identified three lineages corresponding to one described and two potential new species, along with evidence of sympatry. But these studies did not explore whether individuals of S. americanus from different genetic lineages segregate onto different host mouthparts. The present study examines the population structure and microhabitat of 196 individuals of S. americanus from lobsters from five North American localities (from Newfoundland, Canada, to Boston, MA) collected between June and September 2019. Specimens were sequenced at two mitochondrial DNA (mtDNA) markers, a 487 bp fragment of cytochrome c oxidase subunit I (COI) and a 481 bp fragment of 16S rRNA. Phylogenetic analyses recover three distinct lineages of Symbion americanus, corroborating previous studies. Population genetic analyses of individuals belonging to the C and G lineages show clear population structure at the level of host mouthparts. Microhabitat data suggest the segregation of different genetic lineages in S. americanus onto different host mouthparts, perhaps indicating the role of spatial niche partitioning in the incipient speciation of S. americanus.
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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".