Red deer on a remote Scottish island are giving birth earlier in the year - and scientists say it's some of the first evidence ever seen that animals are evolving to cope with climate change.
Previous studies have showed that the deer on the Isle of Rum are giving birth about 12 days earlier than they were in the 1980s.
Now, scientists can reveal that genetic changes caused by natural selection - the theory of evolution developed by Charles Darwin - are also at play on the island.
Professor Josephine Pemberton from the University of Edinburgh has been involved in the study.
(SOUNDBITE) (English) PROFESSOR JOSEPHINE PEMBERTON, EVOLUTIONARY BIOLOGIST SAYING:
"It's very hard to measure that selection has changed over time with the climate changing because it changes so slowly. So this is a response that we've observed over forty years which is consistent with a change in the climate but we can't actually promise that it is due to climate change."
Scientists use a DNA database of every red deer on the island to produce a detailed pedigree for every animal.
It allows them to prove that the animals are changing over time.
They made the discovery using field records and genetic data collected over a 45-year period since 1972.
The study provides a rare example of evolution happening quickly enough to be detected over just a few decades.