Vol. 49 No. 4, 2010
Mitochondrial DNA Variations in Sibling Species of the Bulinus truncatus/tropicus Complex in Lake Albert,
Nalugwa1,*, Thomas K. Kristensen2, Silvester
Nyakaana1, and Aslak Jørgensen2
Biology Laboratory, Institute of Environment and Natural Resources,
Makerere University, PO Box 7298, Kampala, Ugand
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
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.