Cyperus papyrus in Lake Victoria: Genetic Information, Utilisation and Resource Sustainability

Abstract

Many wetlands in the Lake Victoria basin are dominated by Cyperuspapyrus, which are very productive and, therefore, have an important roleboth ecologically and socially. The increasing harvesting pressure ofpapyrus threatens its future. Thus, a conservation approach was employedto determine the intensity of the pressure and threat to the papyrusdiversity at clonal level. Eight microsatellite loci were used for analysingthe clonal diversity and genetic diversity of Cyperus papyrus in 6 swampsof Mwanza bay (Tanzania) and 5 swamps of Nyanza bay (Kenya). From304 individuals, we observed a total of 49 alleles in Mwanza bay and 44alleles in Nyanza bay, a high clonal diversity (R = 0.64 to 1 Mwanza bayand R=0.70 to 1 in Nyanza bay), and a high genetic diversity (HE) with anaverage of 0.558 and 0.493 for Mwanza and Nyanza bay, respectively. Theanalysis of molecular variance showed that most of the allelic varianceswere within individuals. This resulted in a moderate differentiation (FST,0.126 and Nm, 1.7) from all studied population in Lake Victoria. Gene flowwas high between populations within each bay of the Lake (Nm > 4). Theobserved disturbance in the swamps showed no effects on any of thepapyrus diversity variables. The clonal diversity (R) was even higher in thedisturbed swamps than in pristine ones, with values ranging from 0.78 to 1for disturbed, and 0.64 to 1 for pristine swamps. This explains that,although it is a clonal plant, papyrus maintains sexual reproduction andsuccessful seed dispersal, making them resilient to even strongenvironmental and anthropogenic disturbance.