Lazier sea slug species -- species with slower metabolism -- are more likely to survive across large evolutionary timelines. Photo by Pixabay /CC

Aug. 22 (UPI) -- New analysis of species' metabolic rates during the mid-Pliocene epoch suggests higher energy expenditures put animals at greater risk of extinction.

The findings, published this week in the journal Proceedings of the Royal Society B: Biological Sciences, suggest laziness is an effective longterm survival strategy.


When scientists tracked the fates of mid-Pliocene species over the last 5 million years, they found species with higher metabolic rates were more likely to have disappeared.

"Those that have lower energy maintenance requirements seem more likely to survive than those organisms with higher metabolic rates," Luke Strotz, a postdoctoral researcher at the University of Kansas' Biodiversity Institute and Natural History Museum, said in a news release.

Scientists studied the metabolic and extinction rates of mollusk taxa because the animals are abundant in the fossil record. The research could help scientists predict which modern species are most at risk of extinction.

"Maybe in the long term the best evolutionary strategy for animals is to be lassitudinous and sluggish -- the lower the metabolic rate, the more likely the species you belong to will survive," said Bruce Lieberman, professor of ecology and evolutionary biology. "Instead of 'survival of the fittest,' maybe a better metaphor for the history of life is 'survival of the laziest' or at least 'survival of the sluggish."

Authors of the new study acknowledge that there are a variety of factors that effect a species' extinction risk, but the revelation that metabolism plays a role will help scientists more accurately calculate extinction probability.

The new research showed the link between metabolic and extinction rates is most pronounced for species with a limited distribution. Metabolic rate is less of a risk factor for species with a wide distribution across different habitats and ecosystems.

Scientists plan to examine the relationship between metabolism and extinction rates among other animal groups.

"We see these results as generalizable to other groups, at least within the marine realm," Strotz said. "Some of the next steps are to expand it out to other clades, to see if the result is consistent with some things we know about other groups."