Deer evolve to give birth earlier as climate warms
Environment: Animals on Rum show genetic change in just a few decades
Red deer on one of the Small Isles are providing some of the first evidence that wild animals are evolving to give birth earlier in the year as the climate warms.
Genetic changes to red deer on Rum have played a key role in a rapid shift in birth dates in recent years, new research shows.
Previous studies have shown that the deer have been giving birth earlier since the 1980s, at a rate of about three days per 10 years, partly due to the effects of warmer temperatures on the deer’s behaviour and physiology.
Now scientists have revealed that genetic changes caused by natural selection – the theory of evolution developed by Charles Darwin – are also involved.
The study provides a rare example of evolution happening fast enough to be detected over a relatively low number of generations.
A team including scientists from Edinburgh University made the discovery using field records and genetic data collected on Rum since 1972.
Female red deer – called hinds – give birth to a single calf each year, and those that reproduce earlier in the year have more offspring over their lifetime, researchers say.
Their findings show that this is partly because of an association between the genes that make hinds give birth earlier and higher overall reproductive success. As a result, genes for breeding earlier have become more common in the Rum population.
The research involved scientists from the Australian National University and the universities of St Andrews and Cambridge. It was funded by the Natural Environment Research Council. The Isle of Rum National Nature Reserve is managed by Scottish Natural Heritage.
Dr Timothee Bonnet, of the Australian National University, who led the study, said: “This is one of the few cases where we have documented evolution in action, showing that it may help populations adapt to climate warming.”
Professor Josephine Pemberton of Edinburgh’s School of Biological Sciences said: “Longterm studies of individual lifetimes are one of the few ways to understand how populations respond to environmental change and how to manage its effects.”
DARWINISM IN ACTION: Red deer on the Small Isle of Rum have shown a rapid shift in birth dates, three days earlier for every 10 years since the 1980s