Data from: The demographic history of populations experiencing asymmetric gene flow: combining simulated and empirical data.

Population structure can significantly affect genetic-based demographic
inferences, generating spurious bottleneck-like signals. Previous studies
have typically assumed island or stepping-stone models, which are
characterized by symmetric gene flow. However, many organisms are
characterized by asymmetric gene flow. Here, we combined simulated and
empirical data to test whether asymmetric gene flow affects the inference
of past demographic changes. Through the analysis of simulated genetic
data with three methods (i.e. bottleneck, M-ratio and msvar), we
demonstrated that asymmetric gene flow biases past demographic changes.
Most biases were towards spurious signals of expansion, albeit their
strength depended on values of effective population size and migration
rate. It is noteworthy that the spurious signals of demographic changes
also depended on the statistical approach underlying each of the three
methods. For one of the three methods, biases induced by asymmetric gene
flow were confirmed in an empirical multispecific data set involving four
freshwater fish species (Squalius cephalus, Leuciscus burdigalensis, Gobio
gobio and Phoxinus phoxinus). However, for the two other methods, strong
signals of bottlenecks were detected for all species and across two
rivers. This suggests that, although potentially biased by asymmetric gene
flow, some of these methods were able to bypass this bias when a
bottleneck actually occurred. Our results show that population structure
and dispersal patterns have to be considered for proper inference of
demographic changes from genetic data.