Data from: Mitochondrial variation in small brown planthoppers linked to multiple traits and likely reflecting a complex evolutionary trajectory
Jing-Tao, Sun et al. (2019), Data from: Mitochondrial variation in small brown planthoppers linked to multiple traits and likely reflecting a complex evolutionary trajectory, Dryad, Dataset, https://doi.org/10.5061/dryad.72ct11m
While it has been proposed in several taxa that the mitochondrial genome is associated with adaptive evolution to different climatic conditions, making links between mitochondrial haplotypes and organismal phenotypes within the context of an organism’s evolutionary history remains a challenge. Mito-nuclear discordance occurs in the small brown planthopper (SBPH), Laodelphax striatellus, with one mitochondrial haplogroup (HGI) more common in the cold climate region of China relative to another form (HGII) despite strong nuclear gene flow, providing a promising model to investigate climatic adaptation of mitochondrial genomes. We hypothesized that cold adaptation through HGI may be involved, and considered mitogenome evolution, population genetic analyses, and bioassays using reciprocal introgression of SBPH lines to test this hypothesis. In contrast to our hypothesis, chill-coma recovery tests and population genetic tests of selection both pointed to HGII being involved in cold adaptation. Phylogenetic analyses revealed that HGII has evolved from the ancestor more recently than HGI with three non-synonymous changes in ND2, ND5 and CYTB. These molecular changes likely increased mtDNA copy number, cold tolerance and fecundity of SBPH, particularly through a function-altering amino acid change involving M114T in ND2. Nuclear background also influenced fecundity and chill recovery (i.e., mito-nuclear epistasis) and protein modeling indicates possible nuclear interactions for the two non-synonymous changes in ND2 and CYTB. The high occurrence frequency of HGI in the cold climate region of China remains unexplained, but several possible reasons are discussed. Overall, our study points to a link between mtDNA variation and organismal-level evolution and suggests a possible role of mito-nuclear interactions in maintaining mtDNA diversity.