Zebra finch songs alter the behaviour of their chicks' mitochondria

By Carissa Wong.

A bird in the wild.

The images are from HenrikNorway.

The zebra finches sing a song to their eggs to warn them of hot weather, and these calls seem to program the hatchlings' cells to harness energy from food without creating excessive heat. This could help their offspring adapt to warmer temperatures.

The heat calls of the zebra finches increase the reproductive success of their offspring and reduce the growth of offspring in hot nest. A smaller body size may help young birds cope better with higher temperatures as the result is a larger surface area to volume ratio which means they can lose heat more efficiently.

We have proof that when zebra finch eggs are exposed to heat calls, they change how energy-generating units inside cells work in the chick.

Mitochondria convert energy from sugars and fats into a molecule that powers cells. They can use energy from food to make heat.

Mylene Mariette says that hearing heat calls changes the balance of how much heat is produced. The birds don't need as much body heat because they produce moreATP under mild heat.

Birds in the Amazon are adapting to climate change.

Mariette and her colleagues allowed 59 male and 52 female zebra finches to breed and collect the eggs on the same day they were laid. The eggs were kept at 37C for 10 days before being transferred to an incubator.

The researchers played recordings of heat calls from 10am to 6pm every day until the eggs hatched. They played other zebra finch calls that aren't associated with high temperatures in the second incubator.

The team placed the hatched chick in the nest with their foster parents. The researchers placed a mixture of hatchlings from the two groups into the same nest. The temperatures ranged from 22C to 34C for 12 days.

The team collected blood samples from 46 nestlings at 13 days after hatching and measured how well the red blood cells produced heat and heat-trapping substances. They found that birds exposed to heat calls produced more energy than offspring that were not exposed.

The fact that acoustic cues change the function of the mitochondria is impressive. We don't know if these changes remain in the adult stage or if they confer a survival or reproductive advantage.

Understanding the effects of sound on the body is important, given the increasingly noisy world we live in. It is encouraging to know that desert specialists have to cope with the heat, considering the unprecedented rate of climate change.

The journal reference is the Royal Society B.

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