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Title: Evolution and ecology of riverine fish communities of Malawi, with a focus on endangered Cyprinids of the genus Opsardium
Author: Sungani, Harold
ISNI:       0000 0004 6056 6575
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2015
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The fisheries sector in Malawi is a major protein source. However, catches have decreased in all water bodies, including rivers. This has been attributed to unsustainable fishing, dam building, and degradation of spawning habitats through increases in siltation. A better understanding of the biology of riverine species may help to promote management and conservation. Research in this thesis initially focusses on migratory behaviour of three species in the genus Opsaridium within the Lake Malawi catchment. Using new micro satellite markers I demonstrate that the endemic large-bodied lake-river migratory species mpasa (Opsaridium microlepis) and sanjika (Opsaridium microcephalum) show weak spatial genetic structure among breeding grounds, consistent with a lack of natal homing. These results suggest conservation initiatives aimed at improving spawning runs in individual rivers could have broader catchment-level benefits. I also demonstrate that the small-bodied exclusively riverine non-endemic dwarf sanjika (Opsaridium tweddleorum) shows strong population genetic structuring among rivers, suggesting each population represent an individual conservation unit. I then present an overview of the evolution of Opsaridium taking a multigene phylogenetic approach and broader taxon sampling. The results demonstrate the three Malawi species have not radiated within the lake catchment, but instead each lineage has independently colonised the system from neighbouring drainages. These results suggest that riverine faunas assemble from multiple colonisation events, rather than within-catchment speciation. I then take a community-level approach to investigate factors that influence riverine fish community structure in Malawi, using geographical variables, locally-measured environmental variables and bioclimatic variables from global-scale databases. The results demonstrate that all sets of variables contribute to structuring, suggesting both historical dispersal limitation and present day habitat contribute to spatial structure of fish diversity. Together, this thesis provides evidence for processes have shaped genetic and species diversity of river fishes in Malawi, which should inform conservation and management of these important resources.
Supervisor: Genner, Martin J. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available