African Journal of Biotechnology Vol. 4 (10), pp. 1195-1202, October 2005          
ISSN 1684–5315 © 2005 Academic Journals

Full Length Research Paper

Genetic diversity within the genus Cynotilapia and its phylogenetic position among Lake Malawi’s mbuna cichlids

Daud Kassam¹*, Shingo Seki¹ , Bosco Rusuwa², Aggrey J.D. Ambali ² and Kosaku Yamaoka¹

¹Department of Aquaculture, Graduate School of Kuroshio Science, Kochi University, B 200 Monobe, Nankoku-shi, Kochi, 783-8502, Japan.

²Biology Department, Chancellor College, University of Malawi, P.O. Box 280, Zomba, Malawi.

*Corresponding Author. E-mail: kassam@cc.kochi-u.ac.jp, dadeka@yahoo.com, Tel: +81 88 864 5153, Fax: +81 88 864 5148.

Accepted 2 August, 2005

Cynotilapia’s unicuspid teeth, a unique character used to delineate it from all other mbuna genera, leaves evolutionary biologists wondering which is the closest relative to this genus among mbuna cichlids. This genus has only two described species out of the 10-13 species/taxa, whereby the undescribed taxa are either known by their colouration or place where they occur. AFLP genetic marker was used to determine the phylogenetic position of Cynotilapia among the mbuna and also the genetic diversity within this genus. Nei’s genetic distance, frequency of polymorphic loci and average heterozygosity were used to unravel the genetic diversity. The neighbour-joining (NJ) dendrogram revealed that the genus Maylandia is the closest relative to Cynotilapia. Genetic distances were higher among all pairs of undescribed taxa than between the two species (Cynotilapia afra vs. C. axelrodi). Frequency of polymorphic loci and average heterozygosity were also higher within undescribed taxa than in two species. These results, coupled with already known phenotypic differences among these taxa (including colour, a crucial factor in speciation through sexual selection), do provide a strong base to taxonomists who can formally describe these taxa as species. The uncovered genetic differentiation is very important for conservation of this endemic fish fauna.

Key words: Speciation, AFLP, nuclear genome, polymorphism, heterozygosity, mbuna.