The likelihood ratio test between the maximum likelihood three-epoch and two-epoch models was highly significant ( p = 4.52×10 −11 ), showing that at least three periods of different population sizes must be considered to describe the data.
The MKPRF approach is based on a hierarchical Bayesian model which can describe not only the strength and direction of selection at individual loci but also an overall trend of selection across a group of loci.
The wood quality and drought tolerance candidate loci were not in general under positive or negative selection, but the non-conserved disease candidate loci showed a clear trend of positive selection overall.