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Mutational Hazard Hypothesis
The mutational hazard hypothesis is a non-adaptive theory for increased complexity in genomes.[1] The basis of mutational hazard hypothesis is that each mutation for non-coding DNA imposes a fitness cost.[2] Variation in complexity can be described by 2Neu, where Ne is effective population size and u is mutation rate.[3]
In this hypothesis, selection against non-coding DNA can be reduced in three ways: random genetic drift, recombination rate, and mutation rate.[4] As complexity increases from prokaryotes to multicellular eukaryotes, effective population size decreases, subsequently increasing the strength of random genetic drift[1]. This, along with low recombination rate[4] and high mutation rate[4], allows non-coding DNA to proliferate without being removed by purifying selection.[1]
Accumulation of non-coding DNA in larger genomes can be seen when comparing genome size and genome content across eukaryotic taxa. There is a positive correlation between genome size and noncoding DNA genome content with each group staying within some variation.[1][2] When comparing variation in complexity in organelles, effective population size is replaced with genetic effective population size (Ng).[3] In plant and animal mitochondria, differences in mutation rate account for the opposite directions in complexity, with plant mitochondria being more complex and animal mitochondria more streamlined.[5]
- ^ a b c d Lynch, Michael; Conery, John S. (2003-11-21). "The Origins of Genome Complexity". Science. 302 (5649): 1401–1404. doi:10.1126/science.1089370. ISSN 0036-8075.
- ^ a b Lynch, Michael; Bobay, Louis-Marie; Catania, Francesco; Gout, Jean-François; Rho, Mina (2011-09-22). "The Repatterning of Eukaryotic Genomes by Random Genetic Drift". Annual Review of Genomics and Human Genetics. 12 (1): 347–366. doi:10.1146/annurev-genom-082410-101412. ISSN 1527-8204. PMC 4519033. PMID 21756106.
{{cite journal}}: CS1 maint: PMC format (link) - ^ a b Lynch, M. (2006-03-24). "Mutation Pressure and the Evolution of Organelle Genomic Architecture". Science. 311 (5768): 1727–1730. doi:10.1126/science.1118884. ISSN 0036-8075.
- ^ a b c Lynch, Michael (2006-02-01). "The Origins of Eukaryotic Gene Structure". Molecular Biology and Evolution. 23 (2): 450–468. doi:10.1093/molbev/msj050. ISSN 0737-4038.
- ^ Lynch, Michael (2006-10-13). "Streamlining and Simplification of Microbial Genome Architecture". Annual Review of Microbiology. 60 (1): 327–349. doi:10.1146/annurev.micro.60.080805.142300. ISSN 0066-4227.