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. Author manuscript; available in PMC: 2014 Dec 1.
Published in final edited form as: Trends Ecol Evol. 2013 Oct 1;28(12):10.1016/j.tree.2013.09.004. doi: 10.1016/j.tree.2013.09.004

Figure 1. Evolutionary processes within and across species boundaries.

Figure 1

(a) A gene duplication event at the most recent common ancestor (MRCA) of all three taxa, results in two copies (red and green) of a gene within the genome, and as the genome undergoes evolution, these copies evolve, diverge, and might have different fates. (b) In prokaryotic organisms, DNA containing genes might be transferred across species boundaries, e.g., from C to B, resulting in a new gene copy. Further, a similar signature might arise in cases of introgression in sexual species. (c) Hybridization between species A and C amounts to individuals from A and B mating and producing viable offspring such that the genetic material in individuals of B can be traced back to two parental species. The gene tree in each case is shown in the inset.