Origin and Evolution
The mir-2 family originated before the last common ancestor of protostomes, and has been ever since linked to mir-71. The evolution of mir-2 is characterized by successive expansions by duplication events. Since most paralogous microRNAs conserve their function, it has been suggested that mir-2 evolution is dominated by a birth-and-death dynamics driven by random drift.
One mir-2 microRNA in Drosophila, dme-miR-2a-2, is two nucleotides offset with respect to the canonical products of other mir-2 precursors. This is likely to affect the function of that particular microRNA. This functional shift is associated to a change in the genomic distribution of mir-2 sequences in Drosophila. The functional diversification of microRNAs may require breaking the genomic linkage between paralogs, probably to avoid the co-regulation of multiple products by the same regulatory sequences.
In the human parasite Schistosoma mansoni the whole mir-71/mir-2 cluster has been duplicated, and one of the copies is in the sexual chromosome.
Read more about this topic: Mir-2 Micro RNA Precursor
Famous quotes containing the words origin and/or evolution:
“Each structure and institution here was so primitive that you could at once refer it to its source; but our buildings commonly suggest neither their origin nor their purpose.”
—Henry David Thoreau (1817–1862)
“Historians will have to face the fact that natural selection determined the evolution of cultures in the same manner as it did that of species.”
—Konrad Lorenz (1903–1989)