Cytonuclear (or mito-nuclear) discordance describes the discrepancy in

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

relationships using

mitochondrial DNA Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondrion, mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the D ...

(mtDNA) versus nuclear genes (or

nuclear DNA Nuclear DNA (nDNA), or nuclear deoxyribonucleic acid, is the DNA contained within each cell nucleus of a eukaryotic organism. It encodes for the majority of the genome in eukaryotes, with mitochondrial DNA and plastid DNA coding for the rest. ...

, nDNA). In other words, mitochondrial and nuclear gene sequences may lead to different, if not contradictory, phylogenetic trees that show the relationships among

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

. In theory, nuclear DNA and mtDNA sequences should lead to similar phylogenetic tree topologies among species but this is often not the case. Other terms for the concept are ''Nuclear-mitochondrial discordance'' or ''mito-nuclear discordance''.

Examples

An example are Australian rock-wallabies (''Petrogale'') in which several species form a monophyletic group with nDNA genes, but not with mtDNA. This cytonuclear discordance involves at least four operational taxonomic units (OTUs) across four species. Another example is the relationship among grasshoppers ( Orthoptera). Phylogenies based on complete mitogenomes recovered some species as para- or polyphyletic. By contrast, a phylogeny based on nuclear genes derived from transcriptomic data retrieved all species as monophyletic clusters. Many other taxonomic groups display cytonuclear discordance, e.g. Burmese pythons or vipers of the genus ''Cerastes''.

References

Mitochondrial genetics Phylogenetics {{genetics-stub