Retention of an ancestral polymorphism in the Mbuna species flock (Teleostei: Cichlidae) of Lake Malawi

• Published in: Molecular biology and evolution 1993-09, Vol.10 (5), p.1015-1029
• Main Authors: MORAN, P, KORNFIELD, I
• Format: Article
• Language: English
• Subjects: Aulonocara; Biological and medical sciences; Biological evolution; Cichlidae; Freshwater; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; Lethrinops; Pisces
• ISSN: 0737-4038; 1537-1719; 1537-1719
• DOI: 10.1093/oxfordjournals.molbev.a040063

Molecular genetic variation was examined within and among species of the rock-dwelling cichlid fishes (mbuna) of Lake Malawi. Phylogenetic relationships among mbuna mitochondrial DNA (mtDNA) haplotypes were estimated by using restriction-fragment-length polymorphisms. The distribution of these lineages among mbuna species is of particular significance for phylogenetic systematic study of this fauna. Some species were found to be polymorphic for divergent haplotypes that substantially predate their isolation from sister taxa. Repeated speciation events among numerous closely related taxa appear to have been so recent that mtDNA lineage sorting among species is incomplete. Thus, the mtDNA gene tree is not congruent with the putative species tree. These results indicate that analysis of mtDNA alone will not be sufficient for resolution of phylogenetic relationships in the mbuna. Clarification of these relationships will require examination of multiple nuclear loci, because many of these new markers are also likely to retain ancestral polymorphisms.