Wild deer living on a Scottish island have provided some of the first proof that animals are evolving in response to climate change, new research has found.
Scientists have discovered that red deer on the Isle of Rum have undergone genetic changes that have helped them adapt to rising temperatures and shifting weather conditions in recent decades.
They say the results of the study show Charles Darwin’s theory of evolution in action.
Previous studies have shown the dates deer on Rum produce their young has been moving forward since the 1980s, at a rate of about three days per decade.
Analysis shows alterations in the animal’s genetic make-up have played a key role in the rapid shift in birth dates that has taken place.
This has been partly due to the effects of warmer temperatures on the deer’s behaviour and physiology, but also due to genetic changes caused by natural selection.
The research team made the discovery using field records and genetic data collected on Rum over a 45-year period since 1972.
They say the study provides rare evidence of evolution happening quickly enough to be seen over a short timespan.
Academics from the universities of Edinburgh, St Andrews and Cambridge and the Australian National University took part in the study.
“This is one of the few cases where we have documented evolution in action, showing that it may help populations adapt to climate warming,” said lead researcher Dr Timothée Bonnet, of the Australian National University.
Professor Josephine Pemberton, from the University of Edinburgh’s School of Biological Sciences, said: “Long-term studies of individual lifetimes are one of the few ways to understand how populations respond to environmental change and how to manage its effects.”
Sally Thomas, director of people and nature at Scottish Natural Heritage, which manages the Isle of Mull nature reserve, said: “These findings are a fascinating example of the impact climate change may be having on wildlife.
“More and more research is demonstrating climate change is influencing species across the UK and the world.”
Female red deer, known as hinds, give birth to a single calf each year. Those that reproduce earlier in the year have more offspring over their lifetime, the researchers say.
The findings show this is partly because of a link between the genes that make hinds give birth earlier and higher breeding success.
As a result, these genes have become more common in the Rum population over time.
The study, funded by the Natural Environment Research Council, is published in the journal PLOS Biology.