Figure 1

C. briggsae mitochondrial ND5 deletion. A. C. briggsae mitochondrial genome positions of ND5 deletion (dashed line at top) and ΨND5 elements-pseudogenes that originated from duplications of ND5. Arrows = primers for PCR assays [reproduced from [10]]. B. C. briggsae intraspecific phylogeny with C. elegans as outgroup. GL = global intraspecific superclade; KE = Kenya clade; TE and TR = temperate and tropical subclades of GL. C(+) = temperate-clade isolates bearing DRSeq2 compensatory ΨND5-2 alleles; C(-) = those bearing ancestral alleles. % ND5 Del. indicates isolate-specific percentages of total mitochondrial genomes that harbor ND5 deletions as previously determined by qPCR [10] and confirmed by conventional PCR and gel analysis here (Additional file 1, Table S1). Isolates classified for statistical analyses as experiencing high (bold underlined font), low (normal font), or zero-ND5 ("N/A") deletion levels are indicated on the phylogeny. *ND5 deletion levels for the HK104 isolate used here was estimated based on the standard PCR band size assay described in Howe and Denver [10] where the results of the standard PCR assay were shown to correlate positively and significantly with a qPCR method used to estimate deletion levels in the other isolates.