Phylogenetic relationships and the temporal context for the diversification of African characins of the family Alestidae (Ostariophysi: Characiformes): evidence from DNA sequence data

Abstract

Phylogenetic relationships within the family Alestidae were investigated using parsimony, maximum likelihood, and Bayesian approaches based on a molecular dataset that included both nuclear and mitochondrial markers. Multiple representatives of all but two of the recognized alestid genera were included, which allowed for testing previous hypotheses of intergeneric relationships and the monophyly of several genera. The phylogenetic position of the Neotropical genus Chalceus with respect to the family Alestidae was also examined. In order to understand the temporal context of alestid diversification, Bayesian methods of divergence time estimation using fossil data in the form of calibration priors were used to date the nodes of the phylogenetic tree. Our results rejected the monophyly of the family as currently recognized (Alestidae sensu lato) and revealed several instances of poly- and paraphyly among genera. The genus Chalceus was recovered well nested within Neotropical characiforms, thus rejecting the hypothesis that this taxon is the most basal alestid. The estimated mean divergence time for the alestid clade (Alestidae sensu stricto) was 54 Mya with a 95% credibility interval of 63-49 Mya. These results are incongruent with the hypothesis that the origin of the family Alestidae predates the African-South American Drift-Vicariance event.