Data from: Genome-wide SNP markers breathe new life into phylogeography and species delimitation for the problematic short-necked turtles (Chelidae: Emydura) of eastern Australia
Georges, Arthur et al. (2018), Data from: Genome-wide SNP markers breathe new life into phylogeography and species delimitation for the problematic short-necked turtles (Chelidae: Emydura) of eastern Australia, Dryad, Dataset, https://doi.org/10.5061/dryad.t2c668d
Understanding the evolutionary history of diversifying lineages and the delineation of evolutionarily significant units and species remain major challenges for evolutionary biology. Low cost representational sampling of the genome for single nucleotide polymorphisms (SNPs) shows great potential at the temporal scales that are typically the focus of species delimitation and phylogeography. We apply these markers to a case study of a freshwater turtle, Emydura macquarii, whose systematics has so far defied resolution, to bring to light a dynamic system of incipient species held back by low level and episodic exchange of alleles across drainage divides on various timescales. Emydura macquarii is a polytypic species complex comprising a set of allopatric lineages and incipient species at various shallow levels of molecular (and morphological) divergence that can interbreed to exchange alleles and do so where their ranges come into contact. In the context of low-level episodic gene flow, speciation is often reticulate, not a bifurcating process. Species delimitation needs to take into account the pattern of ancestry and descent of diverging lineages in allopatry (phylogenetics) together with the recent and contemporary processes of dispersal and gene flow (population genetics) that retard and obscure that divergence. This combined approach provides a means for addressing the challenges of incompletely isolated populations with uncommon, but recurrent gene flow in studies of species delimitation, a combination likely to be frequently encountered. The accompanying taxonomic judgements can avoid the risk of the taxonomic inflation that can accompany phylogenetic or lineage approaches to species delimitation.