Fig. 8

Bayesian analysis of population structure. Split-and-reanalyze strategy implemented in structure. The entire dataset was initially split into Atlantic- and Mediterranean-draining basins (top left and top right, respectively). The first dataset also includes a population of L. sclateri from a Mediterranean-draining basin (Segura R.) as an allopatric counterpart to L. sclateri from Guadiana R.. The Atlantic-draining dataset was subsequently split into west- and south-draining basins (bottom). Using a combination of changes in consecutive LnP(D) values and Evanno’s [48] ΔK, we determined the most likely number of clusters in each dataset. These analyses indicate that an overall K = 10 populations is the most biologically meaningful genetic structuring of the nuclear dataset. In Additional file 3 we present an alternative strategy to estimate K, using the run with highest likelihood value for each K. The results are very similar, with the detection of additional differentiation within L. bocagei (K = 11)