You might think a chick’s life begins when it busts out of the shell, but research has found that baby birds get to work well before they’ve stepped out into the world (cuckoos even start exercising). Anyone who’s ever witnessed a brood developing will know they get chirping before making their grand entrance, but it turns out the communication isn’t a one-way street. New research has revealed that even at the embryonic stage a developing chick’s physiology can adapt in response to the call of its parents.
Published in the journal Proceedings of the Royal Society B, a new paper outlines the mitochondrial changes that occur in developing zebra finch embryos. The reaction comes in response to their parents’ “heat-calls” which effectively let the eggs know they’re about to enter a warm environment. Something zebra finches are used to living out in the hotter parts of Australia.
The researchers on the study took samples to measure the red blood cell mitochondrial function of zebra finch nestlings that had been incubated under different conditions. Some were exposed to high heat without acoustic cues, while others were in moderate heat but in earshot of heat-calls. Others heard control calls while being stored in contrasting thermal environments. After hatching, they were left to rear with parent birds for 13 days before samples were taken.
You may know mitochondria as “the powerhouse of the cell” and you’d be right, as they convert energy from food into fuel for the cells called adenosine triphosphate (ATP). The researchers were looking to see how – or if – this mitochondrial function changed to make the chicks better adapted to the environment they had been incubated in preparation for.
Their results showed that the red blood cells’ mitochondrial ATP production changed in response to both the temperature the eggs were stored in, as well as the bird’s exposure to heat-calls even when kept in moderate temperatures.
“Hearing heat calls changes the balance of how much ATP versus heat mitochondria produce,” said Mylene Mariette at Deakin University in Geelong, Australia, to New Scientist. “Under mild heat (below 35 °C [95 °F]), mitochondria of heat-call exposed birds produce relatively more ATP, because they don’t need to produce as much body heat.”
This demonstrates that – in the short term, at least – the acoustic cues a developing zebra finch egg is exposed to can alter its physiological function at the mitochondrial level. This is the first time mitochondrial acoustic sensitivity has been demonstrated in research, say the study authors, “and brings us closer to understanding the underpinning of acoustic developmental programming and avian strategies for heat adaptation.”
This is significant in an ever-warming world that’s getting noisier every day, as understanding the significance of acoustic cues on chick development may bolster efforts to conserve habitats and keep the din to a minimum.
[H/T: New Scientist]