Mitonuclear incompatibilities in the two subspecies of the Long-tailed finch

It is really great to see our first paper in this exciting space being published with the paper by Kelsie Lopez being published in Evolution. The paper can be found here. In this paper we report the molecular work that Kelsie did with Daniel Hooper at Cornell, finding a divergence in the mitochondrial sequence of two clades that arose around 0.5 million years ago. This is the kind of spilt that recent theoretical work has suggested might help to drive speciation, and the incompatibility of two closely related forms (lots of cool work by Geoff Hill, and Paul Sunnocks in this area). This spilt in mitochondrial haplotypes is coincident with the Z chromosome divergence that we found earlier, and centred around Kununnurra in the Eastern Kimberley. Hybrid zone females are significantly less likely than males to carry an admixed Z chromosome or have mismatched Z-mitochondrial genotypes, which is a strong indication that there is some cool selection happening here. So a female that has a western Z chromosome, will work better if she also has a western mitochondrial haplotype. Females with a mismatch, like a western Z chromosome and an eastern mitochondrial haplotype are probably less fit and tend to perish at an earlier stag of development. We are following this up with more work in the field and laboratory.

Figure 2. From Lopez et al 2021.

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