Distribution And Phylogeography Of Genus Lobelia In The Flora Of Tropical East Africa

The genus Lobelia belongs to the family Campanulaceae, sub-family Lobeliodeae. The genus comprises of more than 415 species, distributed the entire world. East Africa is one of the centers of the Lobelia distribution and diversity. In flora of tropical East Africa, Lobelia consists of about 50 species with herbaceous and giant form. These species are distributed in variable vegetation regions. Lobelia inhabiting the study region originated 10 MA. However during the recent quaternary climatic fluctuation (2.8 MA) there is alternating cycles of vegetation shift driven by glacial expansion and interglacial. Understanding of the present distribution and identifying the past climatic dynamics refugia is required in setting future conservation strategies.The overall objectives of this thesis are to investigate the distribution of the genus Lobelia and the overarching quaternary climatic oscillations hypothesis in tropical East Africa. I attempted to answer these broad questions in two sub-topics:(1) the genus Lobelia ecological preferences and their population distribution patterns in East African countries; (2) phylogeographic structure and genetic differentiation of Lobelia telekii Schweinf (Campanulaceae) in the alpine flora of Tropical East Africa Mountains.To include the whole of the East African Lobelia’s distinctive ecosystem, we firstly conducted literature review of all habitats in the flora of tropical East Africa. Based on literature review from previous studies on phylogeography, phylogeny, flora books, Nairobi herbarium voucher specimen’s data, palaeoenvironmental and in addition to our present study extensive field work, we identified distribution patterns of members in the genus Lobelia across the six tropical East Africa vegetation regions. Selection of species which occurred in the same region was based on analysis of both altitude and habitat. Therefore from both data of our extensive field work and the Flora of Tropical East Africa, each similar ecological preferences group shared the habitat within a given vegetation region.We therefore, selected six outstanding Lobelia vegetation regions types using a map of East Africa. Among this Lobelias population distribution based on vegetation regions, they were further classified as two mega habitats (low land habitat and the afro montane habitat) depending on topography and physiognomic classification types.The genus exhibited high local species richness, and then the species are distributed at all vegetation regions, and elevation of tropical East Africa. Species initial distribution was driven by individual ecological preferences. Due to ecological preferences Lobelia species of given vegetation region could re-colonize the former habitat during the interglacials from their ecological preference habitat (refugia).Lobelia telekii inhabits the quaternary glaciated alpine zone in three mountains (Mt Kenya, Elgon and Aberdares) while L. aberderica inhabits the mentioned mountains and also Cherangani Hills which neighbors Mt. Elgon. We here used Lobelia telekii as a model plant of alpine species to investigate the impact of hypothesized alpine glaciations, and carried out a detailed molecular investigation in this species to elucidate the haplotypes evolutionary history. Lobelia telekii high haplotype diversity suggests survival in different isolated refugia. Present distribution of L. telekii could have been recently shaped by the quaternary epoch.This thesis sheds light on phylogeography, distribution, and plant protection of lobelias in tropical East Africa.