The evolutionary relationships of present-day species are the result of genetic drift due geographical isolation, gene flow and mutations. Zou et al. use population genetic data to determine interspecific relationships, speciation patterns and gene flow between three Asian spruce species with a similar morphology, Picea wilsonii, P. neoveitchii and P. morrisonicola. Modelling of the data supports the hypothesis that P. morrisonicola derived from P. wilsonii within the more recent past, most probably indicating progenitor-derivative speciation with a distinct bottleneck, although further gene flow from the progenitor to the derivative continued. They conclude that the extent of mutation, introgression and lineage sorting taking place during interspecific divergence and demographic changes in the three species has varied greatly between the three genomes.
