This finding might argue that although differential gene loss on different chromosomal regions is permitted following a WGD through genetic redundancy of cis-regulatory elements, the overall constancy of gene number is strongly selected for by balancing selection at least for transcription factors such as ParaHox genes.
Well-established theories of sexual selection maintain that traits which are favorable in mate choice will be strongly selected for, even if natural selection does not favor these traits.
Considering the first definition – the sum of bite lengths – the explanation is that under strong direct selection, individuals with large bites are strongly selected for and reproduce.
Indeed, T2 was strongly selected for, while genetic trends for T4 showed no selection pressure in any direction (Fig. 4).
Finally, we found that a flexible strategy is not strongly selected for or against by the evolutionary algorithm, but that selection acts on the relative positioning of flexible genes with respect to sleep and eat genes.
The fact that only one such region was detected is not surprising since regions that have been strongly selected for a derived allele in one breed are likely to be selectively neutral in other breeds which do not possess this allele, leading to small differences in flanking SNP allele frequencies and modest FST statistics.
So I think what we can do is to say that this region is strongly selected for faces.
These polymorphisms, including MTHFR C677T in our research, were all striking examples of functional polymorphisms being strongly selected for in human population in response to environmental stresses.
According to Enard et al 2002, the fact that these two differences are fixed in the human genome, whereas no fixed substitutions occurred in the lineage of our closest relatives, the chimpanzees, suggests that those changes were strongly selected for in our lineage; Enard et al. put the date of fixation of these changes in the human population at around 200,000 years ago.
