Mitonuclear interactions impact aerobic metabolism in hybrids and may explain mitonuclear discordance in young, naturally hybridizing bird lineages

Understanding genetic incompatibilities and genetic introgression between incipient species are major goals in evolutionary biology. Mitochondrial genes evolve rapidly and exist in dense gene networks with coevolved nuclear genes, suggesting that mitochondrial respiration may be particularly susceptible to disruption in hybrid organisms. Mitonuclear interactions have been demonstrated to contribute to hybrid dysfunction between deeply divergent taxa crossed in the laboratory, but there are few empirical examples of mitonuclear interactions between younger lineages that naturally hybridise. Here we use controlled hybrid crosses and high resolution respirometry to provide the first experimental evidence in a bird that inter-lineage mitonuclear interactions impact mitochondrial aerobic metabolism. Specifically, respiration capacity of the two mitodiscordant backcrosses (with mismatched mito-nuclear combinations) differ from one another, although they do not differ significantly from the pa..., Study species
Long-tailed finches of each subspecies (Poephila acuticauda acuticauda and P. a. hecki) used in this study came from captive populations maintained at Macquarie University in Sydney, Australia. Wild caught P. a. acuticauda individuals were originally sourced from Mount House (17°02′S, 125°35′E) and Nelson’s Hole (15°49′S, 127°30′E) in Western Australia, and wild-caught P. a. hecki were sourced from October Creek (16°37′S, 134°51′E) in the Northern Territory[34,35]. As individuals from these populations show no evidence of genomic admixture between subspecies[31,32] we hereafter refer to them as ‘parental’.
mtDNA comparison between subspecies 
Changes in the mitochondrial genome are required but not sufficient for inter-lineage mitonuclear incompatibility. Even a single substitution in the mtDNA can lead to reproductive isolation (e.g., [36]). To identify substitutions with the potential to contribute to incompatibilities, we sequenced whole mitochondrial genomes from each ..., , # Mitonuclear interactions impact aerobic metabolism in hybrids and may explain mitonuclear discordance in young, naturally hybridizing bird lineages

[https://doi.org/10.5061/dryad.m37pvmd9v](https://doi.org/10.5061/dryad.m37pvmd9v)

We have submitted our raw aerobic metabolism data (**aerobic_metabolism_data.csv**), embryonic heart rate data (**heart_rate.csv**), mitochondrial copy number data (**mitochondrial_copy_number.csv**), oxidative damage data (**oxidative_damage.csv**), and an R script for analyzing the datasets used in this study (**aerobic_metabolism_analyses_annotated_.R**).

## Descriptions

### aerobic\_metabolism\_data

* *Egg*: Individual embryo ID number
* *Dup*: An embryo that was measured multiple times as a technical replicate is marked 'DUP'
* *Sex*: Sex of embryo
* male
* female
* *OXPI*: Oxidative phosphorylation when only complex I (CxI) is receiving electrons (coupled respiration measurement)
* *OXPI_II*: Coupled respiration capacity thro...