Most of us understand the Darwinian concept that mutations and selective force gradually diversify living organisms.
When groups of plants or animals were separated in their habitat, they grew gradually different from one another and after a certain point they became different species. But, at the genomic level, is it only accumulation of mutations? Are there critical changes that cause speciation? A study in fruit fly genomes by Prof. Albert Ketterman suggests that duplication and rearrangement of genes may play an important role in the speciation process. Comparing sequences of a diverse and multi-functional gene family of glutathione transferase among 12 fruit fly species (Drosophila), Prof. Ketterman and Dr. Chonticha Saisawang discovered that the co-linearity, relative positions and orientations of these genes shows that these genomic rearrangements have occurred many times over the course of evolution and divergence of the 12 species. The genome micro-plasticity appears to have contributed substantially to the evolution of a gene family and ultimately to each species.
Examples of the micro-rearrangements that occur in the individual species
Saisawang C, Ketterman AJ*. Micro-plasticity of genomes as illustrated by the evolution of glutathione transferases in 12 Drosophila species. PLOS ONE. 2014 October;9(10):e109518. Gene rearrangement in speciation of fruit flies.