Demographic models from Table 5 (plus Full Model) ranked using Akaike Information Criterion (AIC).

AIC calculated using -2(log) +2k, (where k is the number of free parameters in the model). Models in bold as in table 5. Based on AIC score the model (ABADE) provides the best fit to our data. This model had equal population sizes between the Negro and ancestral populations and unequal gene flow between Negro and Chubut systems (Table 5). Estimates of the time of divergence (years before present [to the nearest thousand]) between river systems were obtained by dividing t by the geometric mean of the mutation rate across loci ( = 4.008839×10−5: see methods for further details).