Genetic estimates of population structure and gene flow: Limitations, lessons and new directions.

Indirect methods using genetic markers are the primary measure of gene flow levels among interbreeding populations. Results from studies employing these methods are often ambiguous and open to multiple interpretation. This is primarily due to low resolution of molecular markers and low precision of model-based estimates. Studies of paternity, kinship and phylogeography generate the most reliable results. Future studies should employ more powerful analytical methods, analyse loci independently, and attempt to distinguish confounding contributions of vicariance to isolation-by-distance studies. Moreover, direct assessment of movement remains the most valid approach to many key issues in population biology.