Zoological Studies

Vol. 49 No. 4, 2010

Mitochondrial DNA Variations in Sibling Species of the Bulinus truncatus/tropicus Complex in Lake Albert, Western Uganda

Allen Nalugwa1,*, Thomas K. Kristensen2, Silvester Nyakaana1, and Aslak Jørgensen2

1Molecular Biology Laboratory, Institute of Environment and Natural Resources, Makerere University, PO Box 7298, Kampala, Ugand
2The Mandahl-Barth Research Centre for Biodiversity and Health, DBL-Parasitology, Health and Development, Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 57, DK-1871 Frederiksberg C, Denmark

Allen Nalugwa, Thomas K. Kristensen, Silvester Nyakaana, and Aslak Jørgensen (2010) Thirty-nine snail samples morphologically conforming to the Bulinus truncatus/tropicus species complex were collected from 5 populations (Booma, Bugoigo, Piida, Toonya, and Walukuba) on Lake Albert, western Uganda.  Analysis of patterns of sequence variations and evolutionary relationships within and between localities using a 612 bp fragment of the mitochondrial cytochrome oxidase subunit I (COI) gene revealed 5 unique haplotypes defined by 21 polymorphic sites.  The Bayesian and medianjoining network phylogenetic reconstructions partitioned the haplotypes into 2 reciprocally monophyletic clades concordant with B. truncatus and B. tropicus separated by 18 mutational substitutions, corresponding to a 3.0% net sequence divergence.  Sequence divergences between haplotypes ranged 0.2%-3.5%, and significant genetic differentiation was observed in 5 of the 6 population pairwise comparisons.  The 2 sibling species were sympatric in only 1 locality, at Piida.  Our results confirm the existence of 2 evolutionary lineages of the Bulinus truncatus/tropicus species in Lake Albert and underscore the utility of the mitochondrial COI gene in differentiating between sibling species of the B. truncatus/tropicus complex which are otherwise indistinguishable based on the shell morphology.

Key words: Bulinus truncatus/tropicus species complex, Freshwater snails, COI gene, Genetic variation, Lake Albert.

*Correspondence: Tel: 246-414-532789.  E-mail:nallen@muienr.mak.ac.ug