Red deer populations in the Scottish Highlands have genetically evolved over the last four decades to give birth earlier in the year in response to climate change and increasing temperatures, according to new research published in the journal PLOS Biology. The genetic changes highlight a rare case of adaptive evolution occurring over a short time period. It is also one of the first examples of wildlife evolution as a direct reaction to climate change.
The study, led by scientists in the United Kingdom and Australia, built on previous research on red deer populations on Scotland’s Isle of Rum. Starting in the 1980s, the timing of when red deer on the island give birth has shifted earlier 4 days per decade due to rising temperatures. In total, that means birth timing has advanced nearly 2 weeks in 40 years.
The scientists also looked specifically at genetic data collected from the Isle of Rum red deer over 45 years, from 1972 to 2017. They found that the deer with earlier birth dates experienced significantly greater breeding success over their lifetimes, giving birth to a higher total number of offspring than deer that gave birth later in the year. As a result, the genes that cause such early births are now increasingly common among the red deer population – providing a unique demonstration of natural selection at work.
This research is particularly important for understanding how wildlife populations may react to current and future environmental change. “This is one of the few cases where we have documented evolution in action, showing that it may help populations adapt to climate warming,” Timothée Bonnet, a biologist at The Australian National University and the lead author of the study, said in a statement.