As the environment starts to change in more dramatic and extreme ways, many species are likely to feel the effect. Whether it’s a shift in their range as ecosystems alter, or disruptions in their ability to find food, some species will benefit while others will inevitably lose. It is usually thought that the current rate at which the climate is changing is too rapid for animals to adapt, but a new paper suggests that this may not always be the case.
“There is a wealth of fossil evidence which suggests rapid climate shifts don’t provide enough opportunity for many species to adapt, meaning they became extinct or restricted to smaller areas of suitable habitat,” explains Dr Jack Lighten, who co-authored the study published in Royal Society Open Science. Species that are slow-growing and have a long maturation time are thought to be particularly at risk, as changes to their genes cannot be passed down at a quick enough rate.
But there are some long-lived, slow-growing species that have defied all odds and survived multiple extinction events, some of which completely altered the face of the planet. So Lighten focused on sharks, skates, and rays in order to investigate just what it was that allowed them to persist, even when 96 percent of all other animals perished. This suggests that they have some sort of evolutionary strategy to withstand massive environmental changes.
Focusing on two populations of winter skate (Leucoraja ocellata) in the Canadian Atlantic, Lighten found that the population living in the shallower, warmer habitat of the Gulf of St Lawrence (which only appeared around 7,000 years ago) had thousands of changes in gene expression when compared with the more archaic population of skate that typically live in the much deeper waters of the Scotian Shelf. This has seemingly resulted in the warm water fish shrinking in size by 45 percent and speeding up their maturation time to adapt to the toastier water.
These changes in gene expression, known as epigenetic changes, are not actual alterations to the animals' DNA itself – something that typically plays out over much longer periods of time for long-living species such as the winter skate – but instead are modifications to which genes are expressed or not. These changes can occur within the lifetime of a single animal, as shown by the fact that smoking can cause epigenetic changes to humans.
“The winter skate has been able to adapt to a dramatically different environment over a short evolutionary time, with apparently little genetic change,” says Dr Lighten. “These adaptive changes in life history, physiology and phenotype have occurred through epigenetic regulation causing changes in gene expression, enabling the species to respond rapidly to environmental challenges.”
This suggests that the success of groups such as sharks, skates, and rays for hundreds of millions of years may be down to their rapid ability to adapt to environmental changes by altering their gene expression. It also means that other plants and animals may also be able to adapt in a much quicker timeframe than is usually thought.
