Morphology, molecules, and character congruence in the phylogeny of South American geophagine cichlids (Perciformes, Labroidei)

Abstract

Phylogenetic relationships among the Neotropical cichlid subfamily Geophaginae were examined using 136 morphological characters and a molecular dataset consisting of six mitochondrial and nuclear genes. Topologies produced by morphological and combined data under parsimony were contrasted, congruence among different partitions was analysed, and potential effects of character incongruence and patterns of geophagine evolution on phylogenetic resolution are discussed. Interaction of morphological and molecular characters in combined analysis produced better resolved and supported topologies than when either was analysed separately. Combined analyses recovered a strongly supported Geophaginae that was closely related to Cichlasomatinae. Within Geophaginae, two sister clades included all geophagine genera. Acarichthyini ( Acarichthys + Guianacara ) was sister to the ‘B clade’, which contained the ‘ Geophagus clade’ (‘ Geophagus ’ steindachneri + Geophagus sensu stricto , and both sister to Gymnogeophagus ) as sister to the ‘ Mikrogeophagus clade’ ( Mikrogeophagus +‘ Geophagus ’ brasiliensis ), and in turn, the Geophagus and Mikrogeophagus clades were sister to the crenicarine clade ( Crenicara + Dicrossus ) and Biotodoma . The second geophagine clade included the ‘ Satanoperca clade’ ( Satanoperca + Apistogramma and Taeniacara ) as sister to the ‘ Crenicichla clade’ ( Crenicichla + Biotoecus ). Several lineages were supported by unique morphological synapomorphies: the Geophaginae + Cichlasomatinae (5 synapomorphies), Geophaginae (1), Crenicichla clade (3), crenicarine clade (1), the sister relationship of Apistogramma and Taeniacara (4) and of Geophagus sensu stricto and ‘ Geophagus ’ steindachneri (1), and the cichlasomine tribe Heroini (1). Incorporation of Crenicichla in Geophaginae reconciles formerly contradictory hypotheses based on morphological and molecular data, and makes the subfamily the most diverse and ecologically versatile clade of cichlids outside the African great lakes. Results of this study support the hypothesis that morphological differentiation of geophagine lineages occurred rapidly as part of an adaptive radiation.

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