The microbiome divergence in this study was approximated with the Unifrac distance (Lozupone et al., 2011), which is also a phylogenetic measure of overall bacterial relationships, taking into account both the abundance of bacterial taxa, as well as their positions in a phylogenetic tree.
The degree of population divergence in our study varied among the seed and seedling traits that we examined.
Most pairs (79%) showed greater than 8% sequence divergence and more than 98% of species pairs showed greater than 2% sequence divergence in their study (10.9 ± 4.9% (mean ± s.d.%, n = 86) in Echinodamata).
Failure to reject the drift-expectation for color morph divergence in this study (Fig. 6B) does thus not justify any strong claim that selection does not operate at all on these color morphs.
Others have proposed that the pre- versus postvaccination era population changes may have been driven by selective pressure of whole-cell vaccines; the divergence in our study is consistent with this proposal (9 – 11 ).
Most of the genes showing significant divergence in the studied Littorina lineage were specific to pairs of species.
4. Genetic drift can even produce large and constant divergence in continental studies, but can't do so in micro comparisons.
Outliers have been related to adaptive divergence in several studies [ 34- 36]; nevertheless, demography and neutral processes can leave similar signatures to selection in the genome.
However, none of the significantly different genes of the embryo stage was found to be a candidate for adaptive divergence in previous studies.
The average pairwise FST for the genomic regions harboring these markers in this study was 0.033, which was slightly higher than the average FST across the whole genome (0.028), demonstrating that the regions harboring genes indicated to be under directional selection in earlier studies also show increased genomic divergence in the current study.
