Posterior probabilities, q values and alpha coefficients (positive values indicate diversifying selection, negative values are indicative of balancing selection) were calculated.
Values <1 are indicative for purifying selection, whereas values >1 indicate diversifying selection [ 27, 28].
A ω > 1 indicates diversifying selection while a ω < 1 indicates purifying selection.
It is possible that this clustering indicates diversifying selection acting on PPR genes from that region as a result of plants adapting to newly emerging sterility inducing genes.
Our evaluation of selection pressure indicates diversifying selection at the initial duplication event and more recent divergent selection of BSP and WIN4-like subfamily members.
Furthermore, two genes, Saov 0148 and hysA, predicted to be involved in amino acid transport and polysaccharide degradation, respectively, had elevated d N/d S levels indicating diversifying selective pressure (supplementary table S4, Supplementary Material online).
This may indicate diversifying selection, as strong directional selection acting on genes involved in the immune response might have been expected to sweep a disease resistant genotype to fixation during the mass die-off of A. cervicornis due to white-band disease.
Both ancestral and recent gene duplications are associated in several cases with signatures of adaptive sequence evolution, indicating that diversifying selection contributed to lysozyme differentiation.
The overall mean Ka/Ks ratios within each genus and between each genus and an outgroup all indicate that diversifying selection is absent from the CenH3 gene as a whole.
Typically, dN/ dS ratios much greater than one indicate strong diversifying selection, whereas values close to one are compatible with neutral evolution and values significantly less than one are consistent with balancing or purifying selection.
