Dispersal in the desert: ephemeral water drives connectivity and phylogeography of an arid‐adapted fish

Abstract

Aim We examine landscape processes shaping the range-wide phylogeography of a dispersal-limited, desert-dwelling fish (the desert goby, Chlamydogobius eremius) in arid Australia.Location South-western Lake Eyre Basin, central Australia.Methods We obtained sequence data for the mitochondrial cytochrome b gene (n = 513 individuals) and nuclear genetic markers (51 allozyme loci; n ≥ 128 individuals) to investigate the phylogeographic relationships among 51 populations. Sampling spanned multiple habitat types (permanent desert springs, ephemeral rivers) and sub-catchments, and the entire distribution of C. eremius and representatives of its sister species, Chlamydogobius japalpa. Phylogeographic analyses (genetic diversity, AMOVA, Tajima's D, W ST , mismatch distribution) were used to explore the distribution and partitioning of mtDNA variation; principal coordinates analysis and neighbour-joining tree networks were used to explore allozyme variation.Results Three main genetic groups exist across C. eremius/C. japalpa populations. The geographical distributions of these groups reflected the historical and current confluence point of major rivers in the region. Surprisingly, permanent desert springs did not contain higher genetic diversity than ephemeral rivers.Main conclusions Genetic structuring of Chlamydogobius populations revealed unanticipated levels of connectivity, indicating that the ephemeral waters of Lake Eyre have allowed gene flow across drainage boundaries and large distances. Phylogeographic breaks reveal that connectivity relies on temporary surface water, while rapid temporal changes in diversity highlight flooddriven dispersal as the main means of gene flow between localities and habitats. Dispersal pathways reveal that ecological context (life history and tolerance of extreme conditions) has played a key role in shaping observed patterns.

Communities at the extreme: Aquatic food webs in desert landscapes

“…While dispersal strategies appear to allow certain taxa to persist across more physically variable LEB rivers, in temperate streams and isolated pools on the Iberian Peninsula, the opposite pattern was observed, with lentic waterbodies linked to dispersive Coleopteran species (Ribera & Vogler, 2000). Nonetheless, the mechanism underlying this is consistent with what we observed, as Ribera and Vogler's isolated pools were also more ephemeral and required frequent migration for aquatic species, so may be considered more like LEB wa- the broad interconnected network of ephemeral river channels to the persistence of certain aquatic taxa in arid landscapes (Mossop et al, 2015).…”

“…Patterns in fish distributions similarly support the dual ecological significance of permanent and ephemeral habitats, where mound springs are key refuges for the poor swimming desert goby, which shows genetic structuring separated according to the north and south catchments of Lake Eyre (Mossop et al, 2015). Conversely, more actively dispersive species such as spangled perch (Leiopotherapon unicolor) and the Lake Eyre hardyhead (Craterocephalus eyresii) are widespread in hydrologically variable riverine habitats across the LEB without reliance on the spring habitats (McNeil et al, 2011).…”

“…We also tested for an effect of region as genetic isolation between northern (e.g., Algebuckina) and southern (e.g., Warriner Creek) catchments has been detected in previous studies (see Mossop et al, 2015). As compositional differences were found between springs and rivers, the contribution of each taxa to the effect of habitat type was estimated using Bray-Cutis dissimilarity (SIMPER function).…”

The ecology of narrow-range endemic macro-invertebrates of Great Artesian Basin springs

“…fishes), for others molecular investigations continue to reveal cryptic species complexes (e.g. the Wangiannachiltonia radiation (King, 2009), Chlamydogobius eremius (Mossop et al, 2015)). In others, they reveal geographically isolated populations whose divergence is generally indicative of species-level splits Murphy et al, 2010;Ponder et al, 1995).…”

“…These early studies revealed a wide diversity of species, and species descriptions continue at a rapid rate (Figure 1-3). Modern molecular techniques have provided particular insights, uncovering cryptic species complexes (King, 2009) and highlighting the importance of divergent populations within species endemic to GAB springs Mossop et al, 2015;Murphy et al, 2013;Murphy et al, 2010;Ponder et al, 1995) as well as the relict and isolated nature of populations of coastal and tropical wetland species that, whilst not endemic to the system, represent populations with evolutionary histories distinct from their coastal counterparts (Clarke et al, 2013;Gellie et al, 2015). In general, accumulating studies suggest that the GAB springs system is one of high biodiversity, composed primarily of taxa that are found only in springs fed by the GAB and that have small geographical distributions (<50km 2 ) (Fensham et al, 2004b;Fensham et al, 2011;Harvey, 2002;Ponder, 1995).…”