Molecular phylogenetics and biogeography of galaxiid fishes (Osteichthyes: Galaxiidae): dispersal, vicariance, and the position of Lepidogalaxias salamandroides.
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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, and the loss of this migratory phase may be a major cause of speciation.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.read more
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Out of Africa: the slow train to australasia.
TL;DR: It is suggested that P. exigua may rely on passive mechanisms of dispersal, and the marked phylogeographic structure evident across small geographic scales in Australia and South Africa indicates that gene flow among populations may be generally insufficient to prevent the local evolution of monophyly.
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Accumulating evidence for a dispersal biogeography of southern cool temperate freshwater fishes
TL;DR: No compelling evidence indicates that present distributions reflect a former broad Gondwana-based range of these fishes, but a role for dispersal in these fishes is consistent with increasingly common claims for disperseal in other taxa.
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Mitochondrial DNA phylogenetics of the Galaxias vulgaris complex from South Island, New Zealand: rapid radiation of a species flock
TL;DR: Molecular clock calibrations suggest that migratory and non-migratory forms of Galaxias vulgaris complex diverged no earlier than the mid-late Pliocene, and the unresolved relationships among species may reflect a rapid evolutionary radiation, essentially a star phylogeny.
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Marine dispersal as a pre‐requisite for Gondwanan vicariance among elements of the galaxiid fish fauna
TL;DR: Gondwanan vicariance appears to have been preceded by marine dispersal in the few instances where it may explain contemporary galaxiiddistribution, such that these biogeographic mechanisms may sometimes have asynergistic relationship.
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Across the Southern Alps by river capture? Freshwater fish phylogeography in South Island, New Zealand
TL;DR: Phylogenetic analysis of galaxiid fish indicates that western populations, along with populations in the north‐east (N = 18), represent a previously unidentified monophyletic Evolutionarily Significant Unit, possibly a cryptic species.
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