Phenetic and cladistic analyses of the phylogenetic relationships within the genus Daphnia worldwide

Abstract

Phenetic and cladistic analyses of 43 species of Daphnia, based on 42 morphological characters scored from the literature, substantiated the basic split of the genus into two subgenera, Daphnia and Ctenodaphnia. However, the number of sound shared-derived characters supporting this split in the cladistic analyses was poor. No robust structuring was observed within the subgenus Daphnia in the phenetic analyses. Cladistic analyses provided evidence of only two well-defined clades within this subgenus, corresponding to a ‘D. obtusa group’ and a ‘D. ambigua group’, distinct from all other taxa. In the subgenus Ctenodaphnia, both phenetic and cladistic analyses highlighted the distinct differences between D. lumholtzi and all other members of the subgenus. D. magna, and D. cephalata together with D. ornithocephala, also constituted outliers in the phenetic analyses. In the cladistic analyses, D. magna, D. cephalata together with D. ornithocephala, D. carinata together with D. nivalis, and a ‘D. atkinsoni group’, each formed separate clades. The relationships between these clades, and all other taxa within the Ctenodaphnia could not be determined in more detail. The lack of fine definition emphasised the inadequacy of many of the published descriptions of Daphnia taxa.