Molecular Phylogenetics and Biogeography of Galaxiid Fishes (Osteichthyes: Galaxiidae): Dispersal, Vicariance, and the Position of Lepidogalaxias salamandroides

Abstract

The galaxiid fishes exhibit a gondwanan distribution. We use mitochondrial DNA sequences to test conflicting vicariant and dispersal biogeographic hypotheses regarding the Southern Hemisphere range of this freshwater group. Although phylogenetic resolution of cytochrome b and 16S rRNA sequences is largely limited to more recent divergences, our data indicate that the radiation can be interpreted as several relatively recent dispersal events superimposed on an ancient gondwanan radiation. Genetic relationships contradict the findings of recent morphological analyses of galaxioid fishes. In particular, we examine several hypotheses regarding phylogenetic placement of the enigmatic Lepidogalaxias. Although most workers consider Lepidogalaxias to be an unusual scaled member of the Southern Hemisphere galaxioids, it has also been suggested that this species is related to the Northern Hemisphere esocoids. Our data strongly suggest that this species is not a galaxiid, and the alternative hypothesized esocoid relationship cannot be rejected. The species-rich genus Galaxias is shown to be polyphyletic and the generic taxonomy of the Galaxiinae is reassessed in the light of phylogenetic relationships. Juvenile saltwater-tolerance is phylogenetically distributed throughout the Galaxiinae, and the loss of this migratory phase may be a major cause of speciation.

A phylogenetic and biogeographic perspective on the evolution of poeciliid fishes

“…Alignments of ribosomal and transfer RNAs were constructed manually based on secondary structural models (Kumazawa and Nishida, 1993;Ortí and Meyer, 1997;Waters et al, 2000). The mtDNA data set included a total of 4333 alignable characters representing 48 ingroup and seven outgroup taxa; 2607 of these characters were variable and 2184 were parsimony informative.…”

Phylogenetic studies of sinipercid fish (Perciformes: Sinipercidae) based on multiple genes, with first application of an immune-related gene, the virus-induced protein (viperin) gene

“…The actual intron of viperin gene was located by aligning the nucleotide sequences with the published complete viperin gene sequence of S. chuatsi (Sun and Nie, 2004). Alignment of the 16S data was subsequently adjusted manually on the basis of secondary structure following the published model of Galaxias breyipinnis (Waters et al, 2000). All the first two introns of the S7 were aligned using the direct optimization method implemented in the computer program POY 3.0.11 (Gladstein and Wheeler, 2002), with parsimony as the optimality criterion.…”

Variation patterns of the mitochondrial 16S rRNA gene with secondary structure constraints and their application to phylogeny of cyprinine fishes (Teleostei: Cypriniformes)

“…at the order level (Ortí and Meyer, 1997); the familial level (Waters et al, 2000); the subfamily level (Ortí et al, 1996;Harris and Mayden, 2001); the generic level (Moyer et al, 2004); and the species level (Chakraborty and Iwatsuki, 2006;Harris and Mayden, 2001)]. Therefore, the 16S rRNA gene has great potential for the inference of divergences among the cyprinid lineages and resolution of relationships within Cyprininae.…”