Pesavento, Jim J. *; Near, Thomas J.; Cheng, Chi-Hing C.: The Phylogenentic Investigations of the Perciformes (Actinopterygii)
and the Origin of the Antarctic Notothenioidei: Inferences for
Mitochondrial and Nuclear DNA Sequences.
Comprising approximately 9,300 species, the Perciformes represents the largest order of vertebrates. Perciform fishes are the dominate component of vertebrate ocean life. The Antarctic fishes of the Notothenioidei are classified as sub-taxon of the Perciformes. Assessment of notothenioid monophyly is complicated by the lack of resolute phylogenetic hypotheses for perciform fishes. Morphological characters have been unable to unambiguously discriminate among alternative hypotheses due to the lack of informative character states and a propensity of convergent evolutionary trends. DNA sequence data provides an alternative strategy to estimate phylogenetic relationships, especially when morphological characters are uninformative or misleading with regards to reconstructing relationships. In this investigation we have gathered a preliminary sampling of perciform diversity to assess the phylogenetic utility of two mitochondrial genes (16s ribosomal and cytochrome b) and a single-copy nuclear gene (titan). These analyses are used to test hypotheses of perciform relationships based onmorphology, determine if the Notothenioidei represents a monophyletic lineage, and attempt to identify the sister taxon of the Notothenioidei.