Trapped in desert springs: phylogeography of Australian desert spring snails

Authors

  • Nicholas P. Murphy,

    Corresponding author
    1. Department of Genetics, La Trobe University, Bundoora, Vic. 3086, Australia
    Search for more papers by this author
  • Martin F. Breed,

    1. Australian Centre for Evolutionary Biology and Biodiversity, and School of Earth and Environmental Sciences, The University of Adelaide, SA 5005, Australia
    Search for more papers by this author
  • Michelle T. Guzik,

    1. Australian Centre for Evolutionary Biology and Biodiversity, and School of Earth and Environmental Sciences, The University of Adelaide, SA 5005, Australia
    Search for more papers by this author
  • Steven J. B. Cooper,

    1. Australian Centre for Evolutionary Biology and Biodiversity, and School of Earth and Environmental Sciences, The University of Adelaide, SA 5005, Australia
    2. Evolutionary Biology Unit, South Australian Museum, North Terrace, Adelaide, SA 5000, Australia
    Search for more papers by this author
  • Andrew D. Austin

    1. Australian Centre for Evolutionary Biology and Biodiversity, and School of Earth and Environmental Sciences, The University of Adelaide, SA 5005, Australia
    Search for more papers by this author

Nicholas P. Murphy, Department of Genetics, La Trobe University, Bundoora, Vic. 3086, Australia.
E-mail: n.murphy@latrobe.edu.au

Abstract

Aim  We investigate the phylogeographical history and determine the time-scale of population divergence of hydrobiid freshwater snails (genus Trochidrobia) inhabiting groundwater springs in the Australian desert. We test the hypothesis that divergence between geographically distinct snail populations occurred simultaneously due to their isolation in hydrologically discrete spring systems, i.e. ‘trapped in desert springs’.

Location  Groundwater springs of the Great Artesian Basin (GAB) in central Australia.

Methods  DNA sequence data from the mitochondrial cytochrome c oxidase subunit I gene and the nuclear 28S and internal transcribed spacer rRNA genes were used to reconstruct phylogenetic relationships within and among three species of Trochidrobia (Hydrobiidae): T. punicea (13 spring groups, = 90), T. smithi (12 spring groups, = 62) and T. minuta (2 spring groups, = 4). Bayesian relaxed molecular clock analyses and approximate Bayesian computation were used to date lineage divergence and distinguish between alternative biogeographical scenarios.

Results  The diversification of the three Trochidrobia species probably occurred between 2.54 and 9.3 Ma, prior to the formation of the springs c. 1 Ma. Intraspecific divergences within the two widespread species occurred after the formation and colonization of the springs. Coalescent modelling and molecular clock analyses supported a simultaneous radiation of five allopatric intraspecific snail lineages within T. punicea (two lineages) and T. smithi (three lineages) across the GAB springs examined.

Main conclusions  The analyses support the ‘trapped in desert springs’ hypothesis for the diversification of intraspecific lineages within the species T. punicea and T. smithi. This hypothesis suggests that the formation of deserts around Lake Eyre in the early Pleistocene led to the hydrological isolation of spring complexes in the GAB, resulting in significant molecular divergence, but no morphological divergence, of Trochidrobia snail populations.

Ancillary