Unravelling the global invasion routes of a worldwide invader, the red swamp crayfish (<i>Procambarus clarkii</i>)
Bibliographic record
Abstract
Abstract Understanding how introduced species succeed and become widely distributed within non‐native areas is critical to reduce the threats posed by them. Our goal was to reconstruct the main invasion routes and invasion dynamics of a global freshwater invader, the red swamp crayfish, Procambarus clarkii, through the analysis of its genetic variability in both native and invasive ranges. We inferred invasion routes and population structure from the analysis of a fragment (608 base pairs) of the mitochondrial marker cytochrome c oxidase subunit I from 1,062 individuals of P. clarkii in addition to 354 GenBank sequences, for a total of 122 populations (22 natives and 100 invaded). Genetic structure was assessed using analysis of molecular variance and non‐metric multidimensional scaling analyses. We analysed haplotype frequencies for the genetic variability in each locality and region. The haplotype network was depicted by using PopART software. A high haplotype diversity was found in the native range (haplotype diversity [Hd]: 0.90), but also in some non‐native areas, such as western U.S.A. (Hd: 0.80), areas of Mexico (Hd: 0.78), and some hotspots in Europe (e.g. southern Spain or Italy), suggesting a complex pattern of multiple introductions. We grouped all localities in five differentiated groups according to biogeographic origin: the native area, west Americas, east U.S.A., Asia, and Europe. Additionally, the identification of 15 haplotypes shared between at least two localities, the phylogenetic network estimation and indices of genetic differentiation among localities allowed us to identify a large genetic admixture in the native range; the two independent invasion routes (i.e. westwards and eastwards) in U.S.A. from the native range (Louisiana and Texas) with translocations within each area; a stepping‐stone introduction from U.S.A. to Japan (involving few individuals) themselves introduced to China afterwards; the entry of P. clarkii from Louisiana (U.S.A.) into southern Spain and their multiple secondary introductions over Europe as well as other possible introductions in central Europe. Our study emphasises the need for unravelling the global invasion routes and the demographic processes underlying the introduction of exotic species (i.e. admixture, bridgehead invasion effect, and propagule pressure) to control the spread of invasive species. Our findings highlight the value of genetic analyses to identify the geographic origin of source populations as well as the variability of invaded areas in order to reconstruct invasion dynamics and facilitate management of invasive species (e.g. through environmental DNA monitoring).
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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".