Maximum Genetic Diversity (MGD) is a
scientific hypothesis relating to
molecular evolution, which is the study of how and why populations of organisms experience
genetic changes over time.
[1][2][3]
MGD starts with the observation that some regions of the
genome are more likely to preserve
mutations into the next generation than others.
[3][4][5] This difference in the observed rate of mutation means some regions of the genome appear to mutate faster than others, and is theorized to relate to balancing the preservation of vital information relating to a species' function against its ability to mutate and adapt to new
environmental niches.
[2][6][4][5] According to MGD, these regions of the
genome eventually drift into two rough categories: faster-mutating
sections tuned to respond quickly to
environmental pressures and allow
adaptive radiation, as well as slower-mutating
sections involved in an organism's most fundamental instructions.
[2][1]
Because MGD asserts that only slow-mutating genes accurately reflect
shared evolutionary history, relationships between species can alternatively be calculated by their "maximum genetic diversity," which is determined by measuring the frequency of mutations in specific corresponding regions of
orthologous genes instead of using raw overall genetic similarity.
[7][1][4]
Using calculations based on mutations in these slow-mutating genes provides a chart of genetic ancestry that lines up with the fossil record - measurements based on raw genetic similarity yield results that clash with the fossil record.
[2][1][8][9] Also due to this grouping into fast and slow, MGD hypothesizes that over time complex organisms become genetically fragile and less tolerant to mutation as their MGD decreases, since an increasing proportion of their genome will have become slow-mutating over time.
[10]
