For this reason, the frequency of expressed orthologous transcripts in XL and non-target species such as XB and XM is far below 100% as a result of "divergent resolution" – the retention of different (non-orthologous) paralogs of genes in each species [38].
Thus, the tyrosinase gene family is a good example for divergent resolution, i.e., differential loss of gene duplicates in divergent lineages, a mechanism that might facilitate speciation [ 13, 65- 67].
Whereas the underlying mechanisms for the co-retention of WGD-derived ligand-receptor pairs remain to be investigated, these WGD-derived ligand-nGPCR pairs could evolve in a manner similar to the "divergent resolution" model that was proposed to illustrate the separation of different copies of a duplicated gene in allopatric populations during sympatric evolution [59].
It was also suggested that reciprocal gene loss following a WGD can contribute to reproductive isolation through divergent resolution of duplicate copies, foreshadowing the diversification of species [ 18].
Divergent resolution of duplicated genes might facilitate speciation events [ 13, 65- 67].
In addition, we have found evidence for divergent resolution of duplicated pigmentation genes, i.e., differential gene loss in divergent teleost lineages, particularly in the tyrosinase gene family.
Notably, although HoxD14 is present in Polyodon, the lobed-finned fishes, coelacanth, and lungfish possess HoxA14 genes, suggesting divergent resolution of PG14 genes in these lineages.
An alternative driving force in speciation might be divergent resolution, where random paralog losses in two allopatric populations can lead to diversity [ 13- 15].
Gene duplication triggers biological innovation (neofunctionalization; 1), reduces pleiotropy by division of labor (subfunctionalization; 2), contributes to reproductive incompatibilities via divergent resolution [ 3], and generates redundancy [ 4].
This is a type of small chromosomal rearrangement that has been implicated in evolution, and has been suggested to be involved in speciation events through population isolation followed by divergent resolution of duplicate genes [ 20, 41].
For example, it has been argued that WGD promotes speciation via divergent resolution where the loss of different copies of duplicated genes in allopatric populations leads to genetic isolation (Taylor et al. 2001).
