An ecogeographical study and genetic variation of the genus eulophia in selected wetlands of Uganda

Abstract

The study was carried out in some freshwater emergent reed swamps typically dominated by a single reed species and seasonally flooded herbaceous wetlands whose vegetation composition was variable. These were the Kafu River valley, Lake Nabugabo wetlands, Sezibwa river system, Namanve swamp, Lake Victoria wetlands, Lake Mulehe, Lake Mutanda, Kyaka wetlands and Lake Kyoga wetlands. For the genus Eulophia, information on its ecology, geography is limited and was especially lacking for wetlands in Uganda. The lack of this knowledge makes it difficult and in most cases impossible for effective conservation to be proposed and later implemented. The objectives of the study were to determine Eulophia’s diversity, distribution and nature of habitats where they thrive; genetic variation within this genus and establish dangers and risks faced by Eulophia in wetlands in Uganda. Transects, and searching around on time basis for individual plants; atomic absorption spectrophotometry for exchangeable and inexchangeable bases in the soils were used. Available data from the herbarium collections and available data was used to generate the checklist of this genus. In addition, Amplified Fragment length Polymorphism (AFLP) procedure was followed for genetic variation and NTSYSpc 2.01 software used in analysis. Eulophia were found to be widely distributed in Uganda though their current status in the entire nation needs to be reassessed considering the fact that some were last recorded over 50 years ago (thought extinct). Thirty species are known to occur in Uganda and their distribution shown on a map. Eight of these species were considered in this study. This study has established that most occurrences of Eulophia are small consisting of scattered individuals and the human activities that occur in the species’ habitats negatively affect individuals and/or occurrences. There was no significant relationship between edaphic factors and diversity and distribution of Eulophia. It was also established that genetic diversity occurs both within and between sites. AFLP’s distinguished between the individuals. In this cluster analysis of genetic similarities all individuals (100%) were arranged in population (site) specific clusters. Overall representation of relationships among individuals by cluster analysis and ordination was in agreement. This study therefore, comes up with information for monitoring; identifies areas of Eulophia species richness and identifies genetic variation within the genus; it also points at types of threats to Eulophia in wetlands in Uganda and proposes conservation needs.