Occasional paternal inheritance of the germline-restricted chromosome in songbirds

Significance Most if not all songbirds possess a germline-restricted chromosome (GRC) which is believed to be exclusively maternally inherited. However, we show that, in the zebra finch, the GRC can also be paternally inherited and that the potential for paternal inheritance may differ between families. We further show that the genetic diversity of the GRC is extremely reduced compared to the high diversity of mitochondrial DNA lineages, suggesting that a single GRC haplotype has spread through the Australian zebra finch population relatively recently via occasional paternal inheritance. Our study therefore suggests that the GRC has the potential to evolve in a selfish manner, which could result in intragenomic conflict.