First, models M0 and M3 were compared, using a test for heterogeneity between codon sites in the dN/dS ratio value, in which twice the log likelihood difference, 2Δℓ = 560, would indicate a strongly statistically significant result (p < 0.01), reflecting large selective pressure on the soybean expansin superfamily; namely, soybean expansin has undergone strong positive selection.
If for a certain SNP locus one allele is substantially more frequently gained than the other allele, one may hypothesize that the former allele is subject to a larger selective pressure to change copy number.
This may be a result of the large diversifying selective pressure exerted on disease resistance loci as plants are continually adapting to new plant pathogens [ 25].
Of course, if the proportion of transient cells that encounter the niche and become tumor-propagating cells is large, the selective pressure on self-renewal will drop.
In examination of general structural constraints on sequence evolution as seen in Table 3, the hydrophobic core has the strongest negative selection, while residues of intermediate solvent accessibility and those on the surface showed less negative selective pressures with larger variances of selective pressure.
The large proportion of NeuAcα2-6 may exert selective pressure for selection of influenza variants with altered receptor preference for this human-type α2-6 receptor, a crucial first step for generating a human pandemic.
The stability of dfr-genes, despite large changes in the selective pressure, indirectly suggests a low fitness cost of dfr-gene carriage.
Hence, the large quantity and high selective pressure (dN/ dS) of γ ORs suggest that the Chinese alligator relies heavily on airborne odorant detection.
Additionally, we investigated the nature of the evolutionary forces that maintain the size of large proteins despite the selective pressure to minimize DNA maintenance/replication times as well as biosynthetic costs.
The roles of these proteins (and the mitochondria in general) in energetics via oxidative phosphorylation are well known, and it may be that a single causative agent accompanying the diversification of snakes that dramatically altered metabolic demand, or led to a fluctuation in metabolic demand, was responsible for large-scale changes in selective pressure on these proteins.
Scientists had assumed that great mass would have produced selective pressure for the larger sacrum, but now they know that the sacral enlargement came first.
