A new link between the mutation rate of DNA and genome size has been found by researchers in Japan and Australia. They found that in prokaryotes, organisms with higher rates of mutation lose genes more rapidly, which shortens their genomes. Prior to this study, it was widely believed that population size determined prokaryotic genome size. Now, population size is thought to only play a part in this phenomenon, as prokaryotes in larger populations have even been found to have evolved shorter genomes.
Scientists conducted this study by looking at the lineages of various prokaryotic organisms. An evolutionary tree was created for each one, where researchers would then find where the strains diverged from one another. After modeling gene loss, they estimated the rate of mutation, pressure, and population size in order to compare it to the amount of genes lost. A majority of the strains had relationships between rate of mutation and gene loss.
Cause and ways in which these losses occurred are still unknown and under evaluation. There could potentially be a survival-related reason as to why prokaryotes speed up their rate of mutation to shorten their genome, but this is unknown as of late. This study has sparked new questions pertaining to prokaryotic genome size and how it may impact them in the future. It could lead to further discovery and explanation in the vast and diverse group known as prokaryotes.
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