Morphological and Molecular Approaches for Assessing Diversity of East African Freshwater Fishes

  • Sophie Ward

Student thesis: Master's ThesisMaster of Science by Research (MScR)


Conservation and management of freshwater fish in Africa can benefit from improved knowledge of the diversity of species present. This thesis focusses on methods to delimit species using morphological measurements and DNA barcodes. In Chapter 1, I discuss known levels of freshwater fish biodiversity in Africa, threats to African biodiversity, the existence and complications of cryptic species, the current knowledge surrounding freshwater fish biodiversity in Tanzania, catfish biodiversity, and the use of DNA barcoding data in systematics. In Chapter 2, I present a study investigating the use of molecular data in taxonomy, specifically DNA barcoding, in studying Tanzania’s freshwater fish biodiversity. Two different DNA markers (mitochondrial COI and 12S) were used to assess diversity among different barcoding genes and evaluate their utility in separating distinct taxa using neighbour-joining phylogenies. Both markers were equally successful in delimiting morphologically-identified specimens from the Ruaha-Rufiji-Kilombero river catchment into species groups. However, comparisons of these sequences to global reference sequence databases highlighted the absence of publically-available validated reference data for the species included in our study. In Chapter 3, I present a study investigating the use of linear morphological measurement in species identification, focussing on Chiloglanis catfish from South-Eastern Africa. The results support the use of linear measurement data in species delimitation, but also highlight the presence of genetically-distinct yet morphological similar “cryptic” species. Overall, the findings suggest morphological diversity within Chiloglanis has arisen from stabilising selection on the overall fluvial phenotype, potentially coupled with adaptation to specific characteristics of local river systems. In Chapter 4, I discuss the implications of these results for future freshwater ichthyofaunal research in Africa.
Date of Award21 Jan 2021
Original languageEnglish
Awarding Institution
  • University of Bristol
SupervisorMartin J Genner (Supervisor)

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