I am interested in creating Bayesian Skyline Plots to look at demographic changes in certain population groups. However, these populations have very little within population variation. Around 5 polymorphic sites within each population and one dominating haplotype that comprises almost 90% of the population (the rest being rare haplotypes). Because, BSP uses Coalescent processes for the calculations, the sample sizes would have a effect on the results. I wanted to know if sample sizes of around 30 (for DNA alignments of 700bp) would be ideal for carrying out the analysis and expect reasonably good results ?