Slow, sluggish species actually more likely to survive extinction

It may sound counterintuitive at first, but species with lower metabolic rates may be better suited to surviving potential extinction,according to a new study.

The research was conducted by a team from the University of Kansas and suggests the phrase “survival of the fittest” should actually be changed to “survival of the sluggish.”

“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, a co-author of the study. “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.’”

Published in the journal Proceedings of the Royal Society B, the study offers another method to predict the likelihood of extinction for species who will be impacted by climate change.

“We wondered, ‘Could you look at the probability of extinction of a species based on energy uptake by an organism?'” said Luke Strotz, the lead author of the paper. “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.”

The researchers examined the metabolic rates of  299 extinct and living bivalve and gastropod species dating back five million years to the present. A species’s metabolic rate refers to how much energy an individual needs to survive every day.

After analyzing datasets of Atlantic Ocean bivalves, the researchers found that metabolic rate was an accurate predictor of extinction likelihood.

This was especially true of the species that lived in smaller habitats rather than the mollusks and bivalves that were distributed across larger areas.  

“In a sense, we’re looking at a potential predictor of extinction probability,” said Strotz. “At the species level, metabolic rate isn’t the be-all, end-all of extinction — there are a lot of factors at play. With a higher metabolic rate, a species is more likely to go extinct. This will increase our understanding of the mechanisms that drive extinction and help us to better determine the likelihood of a species going extinct.”

For some bivalves and gastropods, the researchers found that energy uptake remained stable over millions of years, lending further credence to the theory that metabolic rate determines a species’ likelihood to thrive or go extinct.

The results suggest that having a lower metabolic rate may advantageous to a species’ survival, but the researchers note that further studies are needed to see if this is true of other groups of species as well.

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By Kay Vandette, Earth.com Staff Writer

Image Credit: Neogene Atlas of Ancient Life / University of Kansas