Positive and purifying selection in mitochondrial genomes of a bird with mitonuclear discordance

• DOI: 10.1111/mec.13203
• Publication Date: 2015-04-16T06:23:15Z
• Authors: Hernán E. Morales; Alexandra Pavlova; Leo Joseph; Paul Sunnucks
• Keywords: Negative selection; Coalescent theory; Lineage (genetic)

Diversifying selection on metabolic pathways can reduce intraspecific gene flow and promote population divergence. An opportunity to explore this arises from mitonuclear discordance observed in an Australian bird Eopsaltria australis. Across >1500 km, nuclear differentiation is low latitudinally structured by isolation distance, whereas two highly divergent, parapatric mitochondrial lineages (>6.6% ND2) show a discordant longitudinal geographic pattern experience different climates. Vicariance, incomplete lineage sorting sex-biased dispersal were shown earlier be unlikely drivers of the discordance; instead, natural female-linked trait was preferred hypothesis. Accordingly, here we tested for signals positive, divergent genes E. We used codon models physicochemical profiles amino acid replacements analyse complete genomes australis, its sister species griseogularis, outgroups. found evidence positive at least five acids, encoded oxidative phosphorylation pathway complexes NADH dehydrogenase (ND4 ND4L) cytochrome bc1 (cyt-b) against background widespread purifying all genes. Three these fixed ND4 geographically most australis lineage. The other ND4L cyt-b more restricted discuss whether may reflect local environmental adaptation, by-product selective processes, or genetic incompatibilities, propose how hypotheses future.