First epigenetic DNA clock can reveal a zebra shark’s age from a blood sample
Zebra sharks carry age-related chemical changes in their DNA that can estimate how old they are with surprising accuracy. A model using only 10 DNA markers came within about 1.6 years of the true age, while larger models reduced the typical error to about one year. The blood-based method could help conservationists measure shark population ages without killing animals, although accuracy drops in older and wild-caught sharks. A shark’s age can be surprisingly hard to pin down, even when the animal is swimming in plain sight. For zebra sharks, researchers have now found a clue in blood: chemical marks on DNA that shift as the animals grow older. A University of Georgia team built what it describes as the first epigenetic clock tested in sharks. The method estimates age by reading DNA methylation, chemical tags that change across the genome over time. Published in Molecular Ecology, the work could give conservation biologists a less harmful way to estimate shark ages. Age structure can reveal whether a population is growing, stable or declining. “Age structure is …
