One of the most intriguing aspects of evolution is the variety of mechanisms species have found to survive, even against all the odds. And it’s even more interesting when the species' approach seems to go against accepted wisdom. This is the case for Atlantic mollusks, whose strategy for survival relies on being lazy.
The study, published in the Proceedings of the Royal Society B, suggests that gastropods (like sea snails) and bivalves with lower metabolic rates are less likely to go extinct. The team looked at species over a period of roughly 5 million years and discovered that those organisms that used less energy in their daily lives were more likely to survive.
"We wondered, 'Could you look at the probability of extinction of a species based on energy uptake by an organism?'" lead author Luke Strotz, from the University of Kansas, said in a statement. "We found a difference for mollusk species that have gone extinct over the past 5 million years and ones that are still around today. Those that have gone extinct tend to have higher metabolic rates than those that are still living. Those that have lower energy maintenance requirements seem more likely to survive than those organisms with higher metabolic rates."
The team believes that their work could be used to help establish which species are at a higher risk of extinction, although they highlight that metabolic rate is just one of many factors that play a part. For example, metabolic rate is a better indicator of extinction risk if the species is confined to a small habitat.
"We find the broadly distributed species don't show the same relationship between extinction and metabolic rate as species with a narrow distribution," Strotz said. "Range size is an important component of extinction likelihood, and narrowly distributed species seem far more likely to go extinct. If you're narrowly distributed and have a high metabolic rate, your probability of extinction is very high at that point."
Interestingly, when the team looked at communities of species, they discovered that the cumulative metabolic rate was stable. It seems like once a species goes extinct, another takes its place in their “metabolic rate” niche.
The team is interested in establishing whether or not this relationship holds for other types of animals. Their focus was on mollusks because of the abundant data on the energy expenditure of both living and dead species. It might not be as easy to study this relationship in other groups. So don’t get lazy just yet, it might not be the right strategy for us.