Climate-driven mitochondrial selection: A test in Australian songbirds

Area of Science:

• Evolutionary biology
• Genomics
• Climate change research

Background:

• Diversifying selection drives lineage divergence and speciation.
• Mitochondrial genomes (mitogenomes) encode oxidative phosphorylation (OXPHOS) proteins, making them susceptible to climate-driven selection.
• Investigating climate's role in mitochondrial evolution is crucial for understanding adaptation.

Purpose of the Study:

• To determine if Pleistocene climate changes influenced mitochondrial selection and evolution in Australian birds.
• To identify specific mitochondrial genes and proteins under selection due to climate.
• To explore parallel selection events in lineages inhabiting similar climates.

Main Methods:

• Phylogeographic analysis of the mitochondrial ND2 gene for 17 songbird species to identify mitolineages.
• Distance-based redundancy analyses to assess climate's predictive power on genetic divergence.
• Analysis of complete mitogenome sequences using codon models and protein homology modeling to detect selection on OXPHOS genes.

Main Results:

• 13 out of 17 species exhibited multiple mitolineages.
• Climate significantly predicted mitochondrial variation in eight species.
• Evidence suggests positive selection on at least two amino acid replacements in OXPHOS complex I (ND6 and ND5 proteins) in specific mitolineages.

Conclusions:

• Pleistocene climate changes have shaped mitochondrial evolution and genetic divergence in Australian birds.
• Specific OXPHOS proteins, such as ND6 and ND5, are potential candidates for climate-associated selection.
• Further research is needed to confirm the functional and evolutionary significance of these mitochondrial candidates.