The fragmented mitochondrial genomes of two Linognathus lice reveal active minichromosomal recombination and recombination hotspots

Evidence for recombination between mitochondrial (mt) minichromosomes has been reported in sucking lice, but it is still not clear how frequent mt minichromosomal recombination occurs. We sequenced the mt genomes of the cattle louse Linognathus vituli and the goat louse L. africanus. Both Linognathus species have 10 mt minichromosomes, and seven of them have the same gene content and gene arrangement. Comparison of mt karyotypes revealed numerous inter-mini chromosomal recombination events in the evolution of Linognathus species. Mini chromosome merger, gene duplication and gene translocation occurred in the lineage leading to Linognathus lice. After the divergence of L. vituli and L. africanus, duplication, degeneration, deletion and translocation of genes also occurred independently in each species. Most of the recombination events in the Linognathus species occurred upstream of either cox3 or nad2, indicating these two locations were hotspots for inter-minichromosomal recombination. Our results provide an important perspective on mt genome evolution in metazoans.

Automated summary

We sequenced the mt genomes of two lice species and found that they share seven minichromosomes with the same gene content and arrangement. Our analysis revealed numerous inter-minichromosomal recombination events, as well as gene duplication, degeneration, deletion, and translocation. The hotspots for inter-minichromosomal recombination were identified as upstream regions of cox3 and nad2 genes. These findings provide important insights into mt genome evolution in metazoans.