EVOLUTIONARY CONSERVATION OF MICROSATELLITE FLANKING REGIONS AND THEIR USE IN RESOLVING THE PHYLOGENY OF CICHLID FISHES (PISCES, PERCIFORMES)

A phylogeny of the principal lineages of cichlid fishes and two other fish families of the suborder Labroidei was based on phylogenetic info rmation from DNA sequences of the flanking region of a (CA)(n)microsat ellite locus. Microsatellite (CA)(n) containing clones from a genomic library of an African cichlid fish from Lake Tanganyika, Tropheus moor ii, were sequenced and primers for the polymerase chain reaction desig ned. All primers amplified the homologous microsatellite loci in many more than the source species and one microsatellite flanking locus (Tm oM27) was particularly conserved and amplified in several lineages of perciform fishes that diverged more than 80-100 million years ago. Des pite the extensive level of evolutionary conservation of this microsat ellite flanking region (MFR), this nuclear region contained reliable p hylogenetic information in the form of both point and length mutations . A phylogeny of cichlids based on this MFR agrees with other phylogen etic hypotheses based on morphological, mitochondrial, and anonymous n uclear DNA. Madagascan and Indian cichlids are found to be paraphyleti c and the most basal group in the family Cichlidae. African and Neotro pical cichlids are both monophyletic and sistergroups. Within African lineages, the East African cichlids are most likely to be monophyletic and the West African cichlids are probably paraphyletic and basal to all African species. The focal microsatellite locus contained much var iation in (CA)(n)repeats in African cichlids and in surfperches (up to 64 repeats), but was short (with only 2-4 repeats) and almost invaria nt in Neotropical cichlids. The design of phylogenetically highly vers atile MFR-primers will be of use not only for phylogeny reconstruction among families of perciform fishes, but also for population-level wor k in the thousands of species belonging to this highly species-rich su border of fishes.