Browsing by Author "Nakintu, Justine"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Environmental Dynamics of Lake Victoria: Evidence from a 10,000 14C yr Diatom Record from Napoleon Gulf and Sango Bay
    (Journal of Environmental Science and Engineering, 2016) Nakintu, Justine; Bunny Lejju, Julius
    Bio-proxies provide relevant information on ecosystem health and environmental dynamics. In this study, diatom assemblages of two cores collected from the Ugandan side of Lake Victoria at Napoleon Gulf (“NAPG1” (GPS, 00º25'44.5" N, 033º14'10.4" E)) and Sango Bay (“SAGB2” (GPS, 00º51'48.0" S, 031º42'47.8" E)) provide evidence of long term changes in the Lake Basin from ca 10,500 years to present. Diatom information was supported by phytolith data from the same cores. The period from ca 10,500-8,100 calyrBP experienced moderate precipitation, strong turbulence with reduced forest cover in the lake’s catchments. During the phase ca 8,100-6,600 calyrBP, the lake basin experienced increased precipitation but with reduced mixing of the water column. This period was also characterized by increased forest vegetation cover as reflected by phytolith assemblages. The period from ca 5,900-1,400 calyrBP was characterized by regular changes in precipitation, turbulence and vegetation taxa in the catchment areas. The phase from ca. 1,800 calyrBP to present was characterized by significant increase in Fragilaria and Nitzschia species as well as increase in Nitzschia: Aulacoseira ratio which may be attributed to human involvement in the ecological functioning of Lake Victoria ecosystem.
  • Thumbnail Image
    Item
    Exploring the genetic diversity of jackfruit (Artocarpus heterophyllus Lam.) grown in Uganda based on SSR markers
    (Genetic Resources and Crop Evolution, 2020) Nakintu, Justine; Albrecht, Christian; Muller, Christina M.; Kagoro-Rugunda, Grace; Andama, Morgan; Olet, Eunice A.; Lejju, Julius B.; Gemeinholzer, Birgit
    Artocarpus heterophyllus Lam. is an economically important tree crop that is widely cultivated inUganda for its fruit. Despite its economic importance, little is known about the genetic diversity of jackfruit in the country. This puts the crop’s genetic resource at risk as farmers selectively grow varieties based on market demand. The study analyzed the genetic diversity of A. heterophyllus trees from 12 districts belonging to three agro-ecological zones and three political regions of Uganda. Ten SSR loci were used to assess the genetic relationship among 200 trees, 197 from Uganda and 3 out-group individuals. All SSR loci were polymorphic with an average of 10.9 alleles per locus. STRUCTURE analysis proposed two genetic clusters: Cluster 1 was composed of samples from Eastern and neighboring Central districts, and Cluster 2 which constituted outgroups and samples from Western and neighboring Central districts. Results of STRUCTURE analysis were confirmed by PCoA. Mbarara District exhibited the highest genetic diversity (He = 0.79, I = 1.71), while Kamuli (He = 0.61, I = 1.08 and Pallisa (He = 0.59, I = 1.12) displayed the lowest genetic diversity despite high abundances of jackfruit trees. Molecular variation was higher within populations than among populations. Moderate and significant genetic differentiation was registered among geographical zones, while varietal differences displayed little insignificant genetic differentiation. Soft and white pulped varieties, considered inferior on the market, harbored private alleles which may be genetically valuable resources. Therefore, sustainable utilization and conservation efforts of the jackfruit genetic resource should consider preserving inferior varieties for future crop improvement.