Summary of proposed molecular evolutionary causes and consequences of heteroplasmic ND5 deletions. The insertion of ψND5-2 (arrow 1) in the ancestor to the global C. briggsae clade (see Figure 2) is hypothesized to result in direct repeat-induced intragenomic recombination events (arrow 2) that in turn lead to heteroplasmic ND5 gene deletions (arrow 3). Expression of truncated ND5 gene products is hypothesized to promote elevated reactive oxygen species levels (arrow 4) that in turn promote higher mutation rates (arrow 5). Accumulation of substitutions (e.g. DRSeq2) in ψND5-2 direct repeats (arrow 2a) are hypothesized to cause reduced intragenomic recombination rates, thereby preventing the elevation of reactive oxygen species levels and associated mutation rate increases.
Howe and Denver BMC Evolutionary Biology 2008 8:62 doi:10.1186/1471-2148-8-62