Roosters run afoul of genetic rules

Researchers caught a rooster doing a hen’s job: passing on mitochondrial DNA to his chicks. Mitochondria, the energy-generating organelles inside cells, carry a circular chromosome containing genes needed to make the mitochondria and keep them running. The long-held rule was that these powerhouses of the cell are inherited only from the mother. But some birds in a 50-generation family of White Plymouth Rock chickens at Virginia Tech broke that rule.

For the study, reported in the October Biology Letters, researchers determined the genetic makeup of mitochondrial genomes from 12 of the chickens. A mutation in the ND4L gene originated in a rooster, the researchers discovered. He passed the mutation to his chicks.

Scientists don’t know how often mitochondria are inherited from fathers in the wild — they’ve seen it in some plants (SN: 5/16/15, p. 8), sheep and even in one person. Such evidence suggests that fathers bequeath mitochondria to their progeny more often than previously suspected. That finding could muddy the results of the many studies that use mitochondrial DNA to trace maternal lineages and determine evolutionary relationships.