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Phylogeography of the freshwater glassfishes (Ambassidae) of eastern Australia: cryptic species and hybrid zones.

Peter Unmack , Michael Hammer, Rachael Remington, Jerald Johnson, Mark Adams

Abstract

Context. We examined freshwater representatives from the family Ambassidae from across eastern Australia to test species boundaries and investigate biogeographic patterns. Aims. To determine whether existing species boundaries are accurate, characterise introgression, and identify and contrast phylogeographic patterns. Methods. Samples were obtained from 115 sites across the range of Ambassis agassizii including representatives from other Ambassis spp from river basins to the west and north. Data were obtained from three independent genetic approaches, allozymes (146 individuals), single nucleotide polymorphisms (239 individuals) and mitochondrial DNA (101 individuals). Key results. Four groups of populations were identified as likely candidate species. The most widespread taxon, A. agassizii had four phylogroups. Complex patterns of introgression were found in narrow contact zones, especially in the Burdekin Basin where all four candidate taxa occur. Conclusions. Freshwater glassfishes have a complex evolutionary history in eastern Australia, with biogeographic patterns which are clearly different to the majority of other co-occurring species. Implications. We provide clarification on the likely taxonomic diversity of the group in eastern Australia, thus providing a basis for more accurate understanding of biodiversity patterns and a solid basis on which to undertake taxonomic revisions and consider conservation issues across these taxa.

MF25007  Accepted 05 March 2025

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