The root of the East African cichlid radiations.
BACKGROUND
For decades cichlid fishes (Perciformes: Cichlidae) of the East African cichlid radiations (Teleostei: Cichlidae) have served as natural experimental subjects for the study of speciation processes and the search for potential speciation key factors. Despite numerous phylogenetic studies dealing with their intragroup relationships, surprisingly little is known about the phylogenetic placement and time of origin of this enigmatic group. We used multilocus DNA-sequence data from five nuclear and four mitochondrial genes and refined divergence time estimates to fill this knowledge gap.


RESULTS
In concordance with previous studies, the root of the East African cichlid radiations is nested within the so called "Tilapias", which is a paraphyletic assemblage. For the first time, we clarified tilapiine intragroup relationships and established three new monophyletic groups:"Oreochromini", "Boreotilapiini" and a group with a distribution center in East/Central Africa, the "Austrotilapiini". The latter is the founder lineage of the East African radiations and emerged at the Miocene/Oligocene boundary at about 14 to 26 mya.


CONCLUSIONS
Our results provide the first resolved hypothesis for the phylogenetic placement of the megadiverse East African cichlid radiations as well as for the world's second most important aquaculture species, the Nile Tilapia, Oreochromis niloticus. Our analyses constitute not only a robust basis for African cichlid phylogenetics and systematics, but provide a valid and necessary framework for upcoming comparative phylogenomic studies in evolutionary biology and aquaculture.
Schwarzer
Julia
J
Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, 53113 Bonn, Germany. j.schwarzer.zfmk@uni-bonn.de
Misof
Bernhard
B
Tautz
Diethard
D
Schliewen
Ulrich K
UK
D000351:Africa, Eastern; D000818:Animals; D001499:Bayes Theorem; D002467:Cell Nucleus / Q000235:genetics; D023681:Cichlids / Q000145:classification / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics; D019143:Evolution, Molecular; D049810:Genetic Speciation; D016013:Likelihood Functions; D010802:Phylogeny; D017422:Sequence Analysis, DNA
D004272:DNA, Mitochondrial