On the relationship between population differentiation and sampling effort: is more always better?


  • Mats Björklund,

  • Sara Bergek

M. Björklund (mats.bjorklund@ebc.uu.se) and S. Bergek, Dept of Animal Ecology, Evolutionary Biology Centre, Uppsala Univ., Norbyvägen 18D, SE–752 36 Uppsala, Sweden.


Given the relative ease by which genotypic data now can be obtained, studies of population differentiation can attain high statistical power provided the number of individuals and loci scored are sufficiently high. This has led to a misunderstanding of the concept of power, and studies with a low number of individuals and loci are dismissed despite highly significant results. This raises statistical, biological and ethical concerns, which we discuss in this note. We suggest that authors should routinely report the number of additional non-significant loci as a measure of the robustness of the results.