Trait-space disparity in fish communities spanning 380 million years from the Late Devonian to present
Bibliographic record
Abstract
The diversity and distribution of species' traits in an ecological community determine how it functions. While modern fish communities conserve trait space across similar habitats, little is known about trait-space variation through deep time or across different habitats. We examined how fish trait diversity varies through space and time by comparing three Late Devonian fish communities — a tropical reef (Gogo, Australia), a tropical estuary (Miguasha, Canada), and a temperate freshwater system (Canowindra, Australia) — with six modern communities from diverse habitats. Trait-space metrics reflecting within-community diversity (functional richness) and species similarity (functional nearest-neighbour distance) indicated Late Devonian communities had scores similar to modern communities. However, they were less functionally rich than their closest modern analogues, and their species tended to be more functionally distinct from one another. Metrics describing location in trait space (centroid distances and hypervolume overlap) showed modern communities were similar to each other, Gogo and Miguasha were similar but distinct from modern communities, and Canowindra was distinct from all others. This pattern suggests period-associated differentiation and substantial heterogeneity among some Late Devonian communities. In addition to temporal changes, we found consistent differences associated with habitat type and climate zone. Reef and tropical communities were the most functionally rich, whereas functional nearest-neighbour scores were highest in estuarine and temperate communities. These results indicate fish community trait space varies with time, habitat and climate, suggesting ( i ) lability in fish trait space and ( ii ) that evolutionary history, environmental filtering, and stochasticity influence community assembly. • The functional trait space of fish communities reflects evolutionary history, habitat, and climate. • Devonian and modern fish communities differ in their trait composition. • Trait differences imply ancient communities functioned differently. • Habitat- and climate-related patterns in functional diversity metrics are consistent across time.
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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 | 0.000 |
| 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".