Phylogeography of Philypnodon species (Teleostei: Eleotridae) across south-eastern Australia: testing patterns of connectivity across drainage divides and among coastal rivers

Abstract

Phylogeographical studies based on DNA sequences offer insights into intraspecific genetic patterns, elucidating the history and structure of populations and their habitats. We used mitochondrial DNA (cytochrome b) to study the phylogeography and population genetics in two sympatric species in the freshwater fish genus Philypnodon throughout south‐eastern Australia. We sought to determine how populations were related across drainage divides, and whether transfer among adjacent coastal drainages was related to continental shelf width or intradrainage distance. Phylogeographical structure was greater in Philypnodon macrostomus Hoese & Reader, 2006 compared with Philypnodon grandiceps (Krefft, 1864), with results for P. macrostomus showing evidence for the presence of distinct groupings in different areas of south‐eastern Australia. There was evidence of drainage‐divide crossings in P. grandiceps in western Victoria, and in P. macrostomus between the Burnett River and the Murray‐Darling Basin in south‐eastern Queensland. Both species showed low levels of divergence along the narrow continental shelf of New South Wales, but as continental shelf width increased moving north in south‐eastern Queensland, population divergence also generally increased. Thus, as the potential riverine connectivity during periods of low sea levels increased, genetic divergences also increased, counter to expectations. Also, population Φst measures did not correlate as predicted with continental shelf width, nor was a significant relationship detected between Φst and the distance between populations. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95, 175–192.

Capacity for thermal acclimation differs between populations and phylogenetic lineages within a species

“…Similar values of Φ for proportion of genetic divergence because of lineage and populations as we found for mosquitofish usually occur in populations across much broader geographic ranges (Thacker et al . ; Liu et al . ).…”

The lasting biological signature of Pliocene tectonics: Reviewing the re‐routing of Australia's largest river drainage system

“…In contrast to the typically strong regional phylogeographic structure detected within southern Australia's freshwater‐limited taxa (above), relatively shallow genetic structure has been detected in riverine taxa that can potentially tolerate estuarine and/or marine conditions (e.g. Philypnodon : Thacker, Unmack, Matsui, Duong, & Huang, ; Galaxias brevipinnis : Waters, Shirley, & Closs, ; Paratya : Cook et al, ; but note regional differentiation in Retropinna : Hammer, Adams, Unmack, & Walker, ; Hughes, Schmidt, MacDonald, Huey, & Crook, ).…”

Significant genetic structure despite high vagility revealed through mitochondrial phylogeography of an Australian freshwater turtle (Chelodina longicollis)

“…The FitzroyDawson and the Burnett drainages both present a mosaic of freshwater isolates where haplotypes could have persisted through hostile Pleistocene conditions. A close relationship between the Burnett drainage and the northern MDB characterises carp gudgeon (Hypseleotris klunzingeri and H. galii) (Thacker et al 2007), lineages of dwarf flathead gudgeon (Philypnodon macrostomus) (Thacker et al 2008), and lineages of hardyhead (Craterocephalus stercusmuscarum fulvus) (Unmack and Dowling 2010), and expose this area as a potentially important source of diversification before expansion into the MDB.…”

“…The complex topography of the Eastern Province could have harboured multiple refugia during glacial cycles. Freshwater taxa including shrimp (Paratya australiensis) (Cook et al 2006), hardyhead (Craterocephalus marjoriae) (Unmack and Dowling 2010), smelt (Retropinna semoni) (Hammer et al 2007), and flathead gudgeon (Philypnodon macrostomus) (Thacker et al 2008) show similarly localised haplotypes and isolation by distance. The Hunter drainage, in particular, likely played an important role in harbouring and promoting diversity during Pleistocene population contraction.…”

“…Faunal connections among the Burdekin, Warrego, and Cooper Creek drainages characterise eight species of freshwater fish (Unmack 2001;Thacker et al 2007). Population connectivity in the south-west between the MDB and the Bass Province is demonstrated in sister lineages of the river blackfish (Gadopsis marmoratus) (Miller et al 2004), Australian smelt (Retropinna semoni) (Hammer et al 2007), subspecies of the freshwater crayfish (Cherax destructor) (Nguyen et al 2004), and in populations of flathead gudgeon (Philypnodon grandiceps) (Thacker et al 2008).…”