Brown, KJ; (2013) Origin, Ecology and Diversification of Lake Tanganyika Mastacembelid Eels (Teleostei: Synbranchiformes: Mastacembelidae). Doctoral thesis , UCL (University College London).

Abstract

This thesis focuses on diversification in mastacembelid or spiny eels (Teleostei: Synbranchiformes: Mastacembelidae) from Lake Tanganyika (LT). LT is the oldest and deepest of the East African Rift Lakes, and is a world-renowned biodiversity hotspot. Chapter One introduces Mastacembelus and the concept of adaptive radiation theory. Chapter Two focuses on the origin and diversity of LT Mastacembelus, including 48% of the African non-LT species. A dated molecular phylogeny demonstrates the monophyly of the endemic Mastacembelus, which colonised LT 7-8 Ma and subsequently underwent rapid radiation forming five main lineages. Chapter Three is a comparative account of pectoral fin diversity within LT, and includes a description of a new species of endemic LT Mastacembelus lacking pectoral fins. Chapter Four incorporates two datasets to address whether LT Mastacembelus exhibit the signature of an adaptive radiation. Firstly, stable isotope analyses are used to estimate trophic niche utilisation and compare how trophic ecology is linked to phylogenetic history. Secondly, morphological diversity of LT Mastacembelus crania is assessed using 3D micro-computed tomography, and compared to the ecological data to test whether morphological traits are correlated to trophic niche exploitation and/or phylogenetic history. Chapter Five builds upon the molecular phylogeny of Chapter Two, by substantially increasing the taxonomic sampling of African species, which is now ~70% complete. This allows the endemic LT radiation to be viewed in the context of almost complete African Mastacembelidae diversity. Extended taxonomic sampling resolves a Congo species within the LT flock; this highlights the affinity of LT and the Congo Basin, and is potentially representative of an emigration and subsequent diversification of an endemic LT species in to the Congo River system. The Congo Basin taxa show high levels of diversity, and are not monophyletic. Chapter Six draws together conclusions about mastacembelid diversity and adaptive radiation, and raises areas for future research.

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