Multi-gene insights into the taxonomy and conservation of Tasmania’s galaxiid fishes

Abstract

Context Galaxiids are a widespread, southern hemisphere, radiation of mostly obligate freshwater fishes. Tasmania houses a diversity of endemic species of Galaxias and Paragalaxias. Of these, many are at risk of extinction, being landlocked, range-restricted and subject to anthropogenic threats, placing a high-conservation priority on the region. Aim Our aim was to synthesise historic and published molecular datasets to provide the sound systematic framework needed to underpin future conservation and taxonomic efforts for Tasmanian galaxiids. Methods Novel and published nuclear (allozyme) and matrilineal (cytb) datasets were generated and integrated for every putative Tasmanian galaxiid species lacking a comparable multi-gene assessment. Key results The Tasmanian galaxiids are phylogenetically diverse, with molecular data generally supporting the accepted taxonomy, but with potential species-level diversity noted within an alpine radiation of the Galaxias truttaceus complex and further support for synonymy of G. niger within G. brevipinnis. Conclusions This study highlights the value of multi-locus studies in both validating species-level taxonomy and resolving taxonomic ambiguities and conservation priorities within Tasmania’s galaxiids. Implications Our integrated genetic analyses provide a framework to underpin more in-depth genomic approaches to assess additional cryptic diversity and conservation planning, such as genetic rescue and ex situ population security.

Phylogeography of a widespread Australian freshwater fish, western carp gudgeon (Eleotridae: Hypseleotris klunzingeri): Cryptic species, hybrid zones, and strong intra‐specific divergences

“…Phylogeographic assessments of freshwater fishes have commonly revealed cryptic species (e.g., Adams et al, 2014;Baumsteiger et al, 2012;Pinacho-Pinacho et al, 2018), thereby improving knowledge of species richness and diversity in aquatic ecosystems globally (Seehausen & Wagner, 2014). In Australia, for example, the number of recognized (but not necessarily described) species increased by 39 between 2002 and 2013 (Allen et al, 2002;Unmack, 2013), with many of the newly defined species revealed by molecular phylogenetic and phylogeographic evidence (Adams et al, 2023). Furthermore, phylogeographic studies have indicated that historical, geological, and/or climatic processes can be determinants of contemporary patterns of biodiversity and distribution across riverine landscapes (e.g., Buckley et al, 2021;Shelley et al, 2020;Waters et al, 2020).…”