Hot, young, dead too soon – why these wrens’ climate future should worry us all
- Monash University biologists undertook a 17-year study of endangered purple-crowned fairy wrens.
- It appears that the hotter things become, the worse the damage to part of the birds’ DNA.
- Professor Anne Peters said the primary message was that climate change held unforeseen risks.
Hot and dry weather damages the DNA of fairy wren nestlings and causes them to age earlier and die younger, according to research that has implications for the effect of climate warming on other species, including humans.
Monash University biologists have undertaken a 17-year study of a population of endangered purple-crowned fairy wrens in the Kimberley, Western Australia, and used blood samples to measure a part of their DNA called a telomere.
A purple-crowned fairy wren. Credit:Doug Adams
Telomeres are pieces of DNA on the ends of chromosomes that prevent them from becoming frayed or tangled (like the aglets at the end of shoelaces). When they become too short to do their job, the ageing process is accelerated.
One of the researchers, Professor Anne Peters from the university’s School of Biological Sciences, said the study discovered wren nestlings that grew up in hot and dry conditions had shorter telomeres.
As a result, these nestlings had a reduced capacity to deal with further DNA damage, meaning they aged earlier and died younger, Peters said.
It appears that the hotter things become, the worse the damage to the telomeres of the week-old nestlings. But this only applies if it’s dry – if it’s wet, the birds’ DNA is unaffected.
“When telomeres get too short, the cell becomes unviable and they malfunction,” Peters says. “At a body level, you start to age. If that goes on for too long, then you die. Long telomeres are great; short telomeres are not”.
The finding, published on Tuesday in the Proceedings of the National Academy of Sciences, builds on previous research from Monash that found the telomeres in seven-day-old nestlings predicted how long they would live and how many young they would produce.
Telomeres are found in all forms of life that have linear chromosomes, including humans.
As animals mature they lose some telomeres due to cell division and also due to stress. In humans stresses such as adversity, mistreatment and hot and dry temperatures can all shorten telomeres.
The damage done by hot, dry weather to the DNA of baby wrens has life-long effects.Credit:Kaspar Delhey
The Monash University researchers took blood samples from 417 birds between 2007 and 2011, and 2016 and 2018. Temperatures during that time ranged between 9 degrees and 48 degrees.
Peters said the wrens breed when the weather is wet and are using all the available windows year-round. Because hot and dry conditions are forecast to increase with climate change, the times when the birds can lay their eggs will diminish.
Monash researchers also ran mathematical models to predict how a drying scenario might affect the purple-crowned fairy wren population size.
They found that under the current climate trajectory, without rapid evolution, the birds’ population would inevitably start declining within a few hundred years.
“Once that process is running, it just goes. You stand by and watch it – there’s nothing you can do any more,” Peters says.
Would the fairy wren be able to evolve to cope with this heat and dryness in that timeframe? It’s uncertain as not much is known about how telomeres evolve. If we were talking about bird wing length or food size … but telomeres are unusual, Peters said.
The primary message is that climate change holds risks we have not yet foreseen, she said.
“Even if we don’t see species declining at the moment, they might already be at risk in ways we haven’t yet foreseen. It’s just another message that we need to act on climate change.”
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