%0 Journal Article
%T Extensive Introgression among Ancestral mtDNA Lineages: Phylogenetic Relationships of the Utaka within the Lake Malawi Cichlid Flock
%A Dieter Anseeuw
%A Bruno Nevado
%A Paul Busselen
%A Jos Snoeks
%A Erik Verheyen
%J International Journal of Evolutionary Biology
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/865603
%X We present a comprehensive phylogenetic analysis of the Utaka, an informal taxonomic group of cichlid species from Lake Malawi. We analyse both nuclear and mtDNA data from five Utaka species representing two (Copadichromis and Mchenga) of the three genera within Utaka. Within three of the five analysed species we find two very divergent mtDNA lineages. These lineages are widespread and occur sympatrically in conspecific individuals in different areas throughout the lake. In a broader taxonomic context including representatives of the main groups within the Lake Malawi cichlid fauna, we find that one of these lineages clusters within the non-Mbuna mtDNA clade, while the other forms a separate clade stemming from the base of the Malawian cichlid radiation. This second mtDNA lineage was only found in Utaka individuals, mostly within Copadichromis sp. ˇ°virginalis kajoseˇ± specimens. The nuclear genes analysed, on the other hand, did not show traces of divergence within each species. We suggest that the discrepancy between the mtDNA and the nuclear DNA signatures is best explained by a past hybridisation event by which the mtDNA of another species introgressed into the ancestral Copadichromis sp. ˇ°virginalis kajoseˇ± gene pool. 1. Introduction The Lake Malawi cichlid fauna comprises over 800 species [1] offering a spectacular example of adaptive radiation with virtually all niches in the lake being filled by members of this family [2, 3]. With a few exceptions, all Lake Malawi cichlids form a monophyletic group as supported by mitochondrial [4¨C6] and nuclear ([7¨C9] but see [10]) markers as well as allozymes [11, 12]. The phylogenetic reconstruction of Lake Malawi cichlid fauna has recovered six main mitochondrial DNA (mtDNA) lineages [5, 6, 10, 13]. Two of these lineages correspond to the Rhamphochromis and Diplotaxodon genera. A third lineage contains the nonendemic riverine Astatotilapia calliptera. The remaining cichlid fauna has been traditionally divided into two groups: one containing predominantly the rock-dwelling species commonly called Mbuna and the second containing the remaining Lake Malawi cichlids. However, phylogenetic reconstructions have shown that both groups are artificial [5, 10, 13, 14]. Several Lethrinops, Aulonocara, and Alticorpus species (ecologically and morphologically typically assigned to the non-Mbuna) cluster within the Mbuna clade. Furthermore, the non-Mbuna genus Copadichromis has been shown to have representatives belonging to both the non-Mbuna clade, as well as to a separate lineage. The genus Copadichromis, together with
%U http://www.hindawi.com/journals/ijeb/2012/865603/