The larger number of losses in teleosts is probably the result of the whole-genome duplication experienced in their ancestor.
In particular, many of the linkage losses may be a consequence of the whole-genome duplication experienced in the S. cerevisiae lineage after the common ancestor of the yeasts analyzed here.
Our results show that extensive triplicate or quadruplicate synteny that is seen on the present day human HOX-bearing chromosomes is not the outcome of two rounds of duplications experienced by a single ancestral block.
Similarly, the genome duplications experienced by the soybean genome during its evolution and the high recombination rates between segmental regions of homologous chromosomes might have increased the occurrence of gene duplications [ 41] and, consequently, favored the expansion and functional diversification of the Gm Hsp20 family.
Higher duplicability may enforce the slower evolutionary rate on AD genes in contrast to other two classes since duplicated genes encounter more purifying selection than singletons even though shortly after the duplication, they experience a considerable relaxation of selection pressure [ 25].
Study on function diversification of duplicated copies of genes revealed that gene copies from genome duplications (polyploidizations) experience different fates during their evolution including gene loss, subfunctionalization [60], and neofunctionalization [47], [61].
After gene duplications, paralogs experience a period of relaxed evolution [ 14], and generally it is difficult to assess how long this period was.
After CBF duplication, CBF2 experienced selective sweeps in the promoter and coding regions, and this may have resulted in its unique functional divergence which differs from those of CBF1 and -3.
They also frequently experience duplication, recombination and diversifying selection, making their evolutionary histories much more complex than those of housekeeping genes [ 20].
We found a significant difference (N = 25, p = 0.025), in good agreement with experiment 1, confirming that people experienced duplication of touch.
