Meeting Abstract
Mitonuclear interactions may be drivers of climate adaptation and lineage divergence. The Eastern Yellow Robin (EYR) shows 6.8% mitogenome sequence divergence between inland and coastal populations. This variation correlates with climatic factors, suggesting possible metabolic local adaptation. Differentiation of the nuclear genomes of populations that bear different mitolineages is heterogeneous for markers mapped to a Zebra Finch (ZF) reference genome; it is particularly strong for a 15.4 MB region mapping to ZF autosome 1A that contains an overrepresentation of nuclear genes (32) with mitochondrial functions. In the hybrid zone of the two mitolineage-bearing EYR populations, differentiation in this 15.4 MB region is strong between females and virtually absent in males. To investigate this, 10x whole genome resequencing data for 100 birds were mapped to a draft EYR genome. The 32 mitonuclear genes from the 15.4 MB region were then mapped to two kinds of EYR scaffold: one limited to females, and one seen in both sexes but with half the read-depth in females than males. This supports the hypothesis that 15.4 MB region may be inherited as a neo-W chromosome with corresponding neo-Z. Neo-sex chromosomes may be overlooked by assuming synteny to a reference. The inferred neo-sex chromosome architecture presents a candidate explanation for the female-limited selection previously indicated in EYR. These ideas are being tested by comparative genomics, measurements of mitochondrial and whole-bird respiration, and fitness estimates.
