Red squirrels appear to be evolving in response to climate change, scientists report today, the first sign that creatures are undergoing genetic alteration due to rising temperatures.
Canadian scientists studying North American red squirrels – which are related to their British counterparts – say compared with 10 years ago, female squirrels are giving birth about 18 days earlier.
Much of the difference from one generation to the next is due to squirrels’ ability to respond to the rise in their staple food, white spruce cones, as temperatures increase. But a small component is due to natural selection, the basis of evolution.
The research, published by the Royal Society, shows that natural selection is favouring squirrels whose genes tend towards breeding earlier in the season. We show that a small part of these changes can be caused by microevolutionary responses, said Denis Réale, of McGill University in Montreal, who led the study of 325 squirrels near Kluane Lake in the Yukon.