Drosophila

Investigating how physiologies & genomes evolve

Montooth Lab

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Causes and consequences of mitochondrial-nuclear coevolution

The unique genetics of the mtDNA are thought to drive compensatory and positive coevolution in nuclear genes. We explore the drivers of this coevolution using population genetic and molecular evolutionary analysis of patterns of mitochondrial mutation and substitution, as well as genetic manipulations to map epistatic interactions between mtDNA and nuclear genomes and quantify genetic variation for the maintenance of uniparental mtDNA inheritance. We are also investigating the consequences of this coevolution for the evolution of the genes involved in mitochondrial-nuclear interactions (Jeff Adrion).

Evolution of mitochondrial-nuclear incompatibilities

In contrast to the well-documented cases of accumulated cytonuclear incompatibilities in Tigriopus, yeast and Nasonia, we have found little evidence that Drosophila accumulate fixed mitochondrial-nuclear incompatibilities. This is likely due to a lower mitochondrial-to-nuclear substitution rate in Drosophila that we believe is a consequence of a biased mutation rate combined with an A+T-rich mtDNA. Nevertheless, segregating mitochondrial and nuclear polymorphisms in different Drosophila species that have little effect on their own can combine to have strong deleterious effects on metabolism, development and reproduction. By mapping these incompatibilities we have shown that the effects these synthetic deleterious alleles can be highly environment-dependent. Interactions of mitochondrial alleles with the intrinsic genetic environment and with the external non-genetic environment weaken the strength of selection, and are critical for understanding mitochondrial disease and co-evolution with the nuclear genome.

Molecular coevolution of tRNA synthetases

One of the mitochondrial-nuclear incompatibilities that we have characterized is between a mitochondrial tRNA and the nuclear-encoded protein that acts in the mitochondria to aminoacylate this mt-tRNA. These RNA-protein interactions are predicted to drive molecular coevolution between these molecules. We are currently using sequence data to detect genomic signatures of this coevolution.

Representative Publications:

Hoekstra, Siddiq, Montooth 2013 Genetics
Meiklejohn et al. 2013 PLoS Genetics
Montooth et al. 2010 Evolution
Montooth et al. 2009 J Mol Evol
Montooth and Rand 2008 PLoS Biol
Meiklejohn et al. 2007 Trends in Genetics

 

Other Research:

cellular adaptation | energetics