Overlapping trophic niches among co‐occurring amphipods from a cryptic species complex
Bibliographic record
Abstract
Abstract Ecological differences among species are usually associated with phenotypic differences that enable species to lessen interspecific competition. Many cryptic species co‐occur in communities, thus raising the question of their ecological equivalency. In the case of freshwater amphipods from the Hyalella azteca cryptic species complex, both ecological differences and overlaps have been reported among species that co‐occur in lakes. Since lakes are heterogeneous habitats that vary in space and time, it is possible that species minimise interspecific competition by occupying different trophic niches. We tested the hypothesis that amphipod species from the H. azteca complex co‐occur by feeding on different food resources in the littoral zone of boreal lakes. We compared the stable isotopes ratios (δ 13 C and δ 15 N) of amphipods from different species, and reconstructed their diets using mixing models. We showed that H. azteca amphipods from different species had isotopic compositions and habitat uses that greatly overlapped. Differences in isotopic composition often occurred, but they were also observed for amphipods of the same species sampled at different depths. This suggests that H. azteca amphipods fed mainly on resources that were available at the site where they occurred rather than distributed according to the occurrence of a specific resource. The overlap in diets suggests that H. azteca amphipods had overlapping trophic niches. Therefore, niche partitioning for food resources was not a process explaining the co‐occurrence of these species within these lakes. Competition for food resources was not likely an important mechanism to explain H. azteca species assemblages in communities. Each H. azteca species apparently fed on food items that were abundant in the littoral zone of lakes, meaning that competition for food might be avoided most of the time. If food scarcity ever happens, the period of scarcity is probably too short to allow the exclusion of one amphipod species by competitive exclusion because of the low differences in fitness between the species, allowing Hyalella cryptic species to co‐occur during the open‐water season. Neutral mechanisms and ecological drift might also influence assemblage dynamics.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| 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".