Concerted Evolution- A definition Concerted evolution is the phenomenon where paralogous genes within one species are more closely related to one another than to members of the same gene family in closely related species. In other terms, when specific members of a family are investigated, a greater amount of similarity is found within a species rather than between species. This is suggesting that members within this family do not in fact evolve independently of one another. The concept of concerted evolution is a molecular process which leads to the homogenization of DNA sequences. As shown from the diagram on the right, as each organism evolves, it creates a species that is more closely related to their genes than anyone else in their species. This is demonstrated by the different colors of circles. If each different color is representing a different organism in one species, this is showing that once the blue and the orange reproduce, they create organisms that are incredibly alike to them (thus they are represented as the same color) This fundamental process operates in all organisms, even if it doesn't seem ultimately present at every moment. Causes Concerted evolution (phenomenon of duplicated genes) may often be caused by the genetic exchange known as gene conversion. This other phenomenon is known as the "non-reciprocal exchange of genetic material between homologous sequences." Gene conservation can do a few things... Decrease mutational load Eliminate deleterious mutations Spread advantageous alleles ...thus playing a role in concerted evolution. Gene conversion is also reliant on the gene sequences that are involved in the current process. Some entire gene sequences have undergone the process of concerted evolution whereas others have a more mosaic pattern where some genes are homogenized, and others diverge without this conversion. Example An example can be seen in bacteria: Escherichia coli (can cause severe food poisoning in hosts) has seven operons encoding various Ribosomal RNA. For each of these genes, rDNA sequences are essentially identical among all of the seven operons (sequence divergence of only 0.195%). In a closely related species, Haemophilus influenzae its six ribosomal RNA operons are entirely identical. When the 2 species are compared together however, the sequence divergence of the 16S rRNA gene between them is 5.90%. Factors Affecting the Rate of Concerted Evolution The specific number of repeats counted The arrangement of those repeats aforementioned (dispersed vs. clustered) Relative sizes of slowly and rapidly evolving