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Evolutionary insight into South African freshwater crabs (Potamonautes) based on genetics and morphometrics
Thesis (MSc)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613907493847040 |
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| access_status_str | Open Access |
| author | Gunkel, Kallyn Graham Roger |
| author2 | Daniels, Savel R. |
| author_browse | Daniels, Savel R. Gunkel, Kallyn Graham Roger |
| author_facet | Daniels, Savel R. Gunkel, Kallyn Graham Roger |
| author_sort | Gunkel, Kallyn Graham Roger |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132399 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:43:36.390Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132399 Evolutionary insight into South African freshwater crabs (Potamonautes) based on genetics and morphometrics Gunkel, Kallyn Graham Roger Daniels, Savel R. Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. Freshwater crabs -- Evolution -- South Africa Freshwater crabs -- South Africa -- Phylogeny Potamonautidae -- South Africa -- Phylogeny Crabs -- Morphology Crabs -- Morphology Animal populations -- Data processing UCTD Thesis (MSc)--Stellenbosch University, 2025. Gunkel, K. G. R. 2025. Evolutionary insight into South African freshwater crabs (Potamonautes) based on genetics and morphometrics. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/6874c758-279a-4d6e-bc1a-f27a3a88fef6 ENGLISH ABSTRACT: In this study, we investigated two key aspects of the evolutionary history of southern African freshwater crabs in the genus Potamonautes. First, we explored the phylogeographical history of the mountain-dwelling crab Potamonautes mariepskoppie to uncover evolutionary processes and identify potential hidden lineages. Using maximum likelihood and Bayesian inference methods, we analysed DNA sequence data from mitochondrial loci (COI, 12S rRNA, and 16S rRNA) and a nuclear locus (histone 3). We tested species delimitation using four approaches: ASAP, bPTP, bGMYC, and STACEY. We applied divergence time estimation and ecological niche modelling with ENMEval and MAXENT to examine species distribution and investigate the abiotic factors influencing evolution. The analyses revealed three distinct clades corresponding to the geographical regions of Limpopo, Mpumalanga, and Mount Sheba. These clades exhibited no shared haplotypes and moderate genetic differentiation. Divergence time estimates suggested that the clades diverged during the Plio/Pleistocene, a period marked by significant climatic changes in southern Africa. All species delimitation methods supported the recognition of these clades as distinct species, although discriminant function analyses of carapace characteristics showed overlap. Ecological niche modelling identified rainfall as a critical factor in species distribution, underscoring the need for further fine-scale investigations of high-elevation regions in Limpopo and Mpumalanga to uncover additional undocumented biodiversity. Second, we examined the convergent evolution of carapace and pereiopod traits across 18 species of Potamonautes. Molecular phylogenetics identified three ecological guilds - mountain stream, riverine/lowland stream, and burrowing species - that exhibited similar morphological traits despite dispersal across the phylogeny. We used DNA sequence data from three mitochondrial loci (COI, 12S rRNA, and 16S rRNA) and one nuclear locus (histone 3) to construct a phylogeny using the maximum likelihood and Bayesian inference methods. We then compared the phylogeny to morphometric data from the carapace and pereiopod measurements. We assessed morphological convergence across guilds using ancestral state reconstruction, principal component analysis (PCA), and phylogenetic generalised least squares (PGLS) analyses. We detected significant convergence, especially in the carapace morphology of riverine species and the pereiopods of burrowing species. Principal component analysis revealed habitat-specific clustering and PGLS analysis confirmed that habitat is a major driver of convergence. These findings suggest that traditional morphological traits alone may be insufficient for species delineation in Potamonautes and emphasise the importance of integrating molecular and morphological approaches in understanding evolutionary processes in freshwater taxa. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2025-06-06T06:24:18Z 2025-06-06T06:24:18Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132399 Stellenbosch University xii, 95 pages : illustrations, maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Freshwater crabs -- Evolution -- South Africa Freshwater crabs -- South Africa -- Phylogeny Potamonautidae -- South Africa -- Phylogeny Crabs -- Morphology Crabs -- Morphology Animal populations -- Data processing UCTD Gunkel, Kallyn Graham Roger Evolutionary insight into South African freshwater crabs (Potamonautes) based on genetics and morphometrics |
| title | Evolutionary insight into South African freshwater crabs (Potamonautes) based on genetics and morphometrics |
| title_full | Evolutionary insight into South African freshwater crabs (Potamonautes) based on genetics and morphometrics |
| title_fullStr | Evolutionary insight into South African freshwater crabs (Potamonautes) based on genetics and morphometrics |
| title_full_unstemmed | Evolutionary insight into South African freshwater crabs (Potamonautes) based on genetics and morphometrics |
| title_short | Evolutionary insight into South African freshwater crabs (Potamonautes) based on genetics and morphometrics |
| title_sort | evolutionary insight into south african freshwater crabs potamonautes based on genetics and morphometrics |
| topic | Freshwater crabs -- Evolution -- South Africa Freshwater crabs -- South Africa -- Phylogeny Potamonautidae -- South Africa -- Phylogeny Crabs -- Morphology Crabs -- Morphology Animal populations -- Data processing UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132399 |
| work_keys_str_mv | AT gunkelkallyngrahamroger evolutionaryinsightintosouthafricanfreshwatercrabspotamonautesbasedongeneticsandmorphometrics |