Phylogenetic Relationships among Fantail Darters (Percidae: Etheostoma: Catonotus): Total Evidence Analysis of Morphological and Molecular Data

Abstract

Results of a phylogenetic analysis of the complete mitochondrial cytochrome b gene (1140 base pairs) for all species of Catonotus are presented along with a synthesis and phylogenetic analysis of published morphological data. The two datasets are combined in a total evidence analysis, and results from the molecular, morphological, and total evidence datasets are compared with each other and with previously published hypotheses. Phylogenetic relationships suggested by morphological data are similar to those from previous studies. The cytochrome b and total evidence analyses also produced trees that are generally congruent with previous hypotheses. The monophyly of the Etheostoma squamiceps group and the monophyly of a clade including members of the E. virgatum and E. flabellare groups are well supported. However, in contrast to traditional classification, E. barbouri usually clustered with the E. flabellare group, and E. percnurum usually clustered with the E. virgatum group. Etheostoma percnurum and E. barbouri possess many autapomorphies, and it is possible that they share fewer cytochrome b characters with close relatives than they share with other species due to homoplasy resulting from accelerated rates of evolution. Also, in contrast to earlier hypotheses, the molecular and total evidence analyses suggested that E. squamiceps, E. crossopterum, and E. olivaceum are closely related. An earlier hypothesis based on morphology suggested that E. olivaceum was basal to other members of the E. squamiceps group and that E. squamiceps was related to E. chienense, E. pseudovulatum, E. oophylax, and E. neopterum. Etheostoma olivaceum has been considered basal because it lacks putative synapomorphies of all other members of the E. squamiceps group. Although reversals (in E. olivaceum) and convergence (in E. squamiceps) in character states are possible, a test of the two hypotheses of relationship requires additional data.