<i>Phormidium Retzii</i> (Oscillatoriales): Genotypic Variation and Phenotypic Plasticity
Bibliographic record
Abstract
Abstract Phormidium retzii is one of the most commonly encountered lotic taxa in North America and has been recorded from a wide range of habitats worldwide. The genetic variability of this cosmopolitan, freshwater cyanobacterium was assessed using gene sequences and random amplified polymorphic DNA (RAPD) markers. Strains consistent with the morphological species circumscription were utilized from British Columbia, Canada to Rio Claro, Costa Rica, and from Rhode Island to Washington State, USA. In addition, some strains were from geographically close (<25 miles apart) sites. The 16S rRNA gene was sequenced for eight of the 12 strains. Sequence homology ranged from 90.95 to 98.71. The nine RAPD primers utilized yielded a total of 133 distinct bands from the 12 strains. The strains were variously related and showed great variation in pairwise genetic distances (0.23–0.83). Given the lack of sequence similarity, P. retzii as presently circumscribed most likely represents several cryptic species not clearly distinguishable with light microscopy of morphological characters. This conclusion may explain the lack of correlation between geographic proximity and genetic similarity. To assess the level of environmentally induced phenotypic plasticity of this taxon, one strain was subjected to three different current velocity and nutrient regimes (low, medium, and high) employing six stream mesocosms. ANOVAs and Bonferroni multiple comparison tests were performed with cell volumes, ratios of cell length : width and percent cover data. Low nutrient treatments elicited significantly (P < 0.05) greater cell volumes and percent cover than did high treatments. Furthermore, current velocity did not show any significant effect on cell morphology. As such, it appears that a single strain is capable of wide morphological variability in response to some environmental conditions. The results of these two studies have great implications in the utilization of cyanobacterial morphospecies concepts.
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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 | 0.000 | 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".