Alternatively, "divergent evolution" can be applied to molecular biology characteristics. This could apply to a pathway in two or more organisms or cell types, for example. This can apply to genes and proteins, such as nucleotide sequences or protein sequences that derive from two or more homologous genes. Both orthologous genes (resulting from a speciation event) and homologous genes (resulting from gene duplication within a population) can be said to display divergent evolution. Because of the latter, it is possible for divergent evolution to occur between two genes within a species.
In the case of divergent evolution, similarity is due to the common origin, such as divergence from a common ancestral structure or function has not yet completely obscured the underlying similarity. In contrast, convergent evolution arises when there are some sort of ecological or physical drivers toward a similar solution, even though the structure or function has arisen independently, such as the different characters converge on a common, similar solution from different points of origin. In other words divergent evolution is where animals closely related evolve different structures.
In complex structures, there may be other cases where some aspects of the structures are due to divergence and some aspects that might be due to convergence or parallelism. In the case of the eye, it was initially thought that different clades had different origins of the eye, but this is no longer thought by some researchers. It is possible that induction of the light-sensing eye during development might be diverging from a common ancestor across many clades, but the details of how the eye is constructed--and in particular the structures that focus light in cephalapods and vertebrates, for example--might have some convergent or parallel aspects to it, as well. (See Gehring reference below and other researchers cited in that research field).
Divergent evolution of arrested development in the dauer stage of Caenorhabditis elegans and the infective stage of Heterodera glycines.(Research)
Oct 05, 2007; Authors: Axel A Elling [1,2,3]; Makedonka Mitreva ; Justin Recknor ; Xiaowu Gai [6,7]; John Martin ; Thomas R Maier ;...
Divergent evolution and molecular adaptation in the Drosophila odorant-binding protein family: inferences from sequence variation at the OS-E and OS-F genes.(Research article)(Report)
Nov 27, 2008; Authors: Alejandro Sánchez-Gracia (corresponding author) [1,2]; Julio Rozas BackgroundThe olfactory system of animals allows...