Abstract
Freshwater fish are among the most threatened vertebrates as a result of increased anthropogenic activity in recent years. Despite the extent to which freshwater environments are known to harbour high levels of biodiversity, it is believed that there are large amounts of unrecognised diversity within freshwater fish populations. Strong spatial structure between distinct populations suggests that geographic barriers preventing the dispersal of species and causing reproductive isolation are the drivers behind speciation, specifically within riverine drainage basins. Secondary contact following geological events has also created the need for habitat specialisation and niche occupation within species living in sympatry leading to spatial structure not just between habits but also within them.Chapter 1 reviews the current literature regarding speciation and drivers of diversity in freshwater environments and examines previous phylogenetic analyses uncovering unrecognised diversity in African catfish. Chapter 2 presents a phylogenetic study into East African catfish belonging to the genus Chiloglanis using next generation sequencing techniques to investigate levels of cryptic biodiversity. The results confirm the strong endemic spatial distribution of Chiloglanis species consistent with their typical restriction to single catchments, in addition to identifying multiple distinct clades in a region of which there is limited previous knowledge. These results confirm the hypothesis that there is unrecognised endemic diversity within Chiloglanis populations and the strict limitations to species ranges suggest that catchment boundaries may act as a geographic barrier preventing gene flow between neighbouring populations and driving the process of speciation.
| Date of Award | 12 May 2020 |
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| Original language | English |
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| Supervisor | Martin J Genner (Supervisor) |