Discovering the evolutionary secrets of plankton

Published 15 October 2018

Russell Bicknell spent weeks peering through a microscope at 1459 separate slides of prehistoric plankton “half the size of a speck of dust” to confirm a theory that evolution operates at different speeds.

His work, done in collaboration with a multi-partner team and published in iScience this week, showed that rapid evolutionary changes occurred in plankton microfossils called Truncorotalia around 5.3 million years ago.

It was not the plankton that interested Russell and his team, but the evolutionary story and rate of change in the animals. Plankton were thought to be a classic representative of Charles Darwin’s “gradualism” model of evolution, in which evolutionary changes take place slowly as a result of competition and changing environments.

But Russell’s weeks at the microscope, coupled with some advanced statistical methods, showed that Truncorotalia changed in a relative blink of the evolutionary eye.

“The rate of change in these microfossils supports a couple of theories, the Quantum Evolution and Punctuated Equilibria hypotheses, proposing that rapid evolutionary leaps can be made,” he says.

“It confirms that evolution in plankton isn’t always a gradual process. It can operate at different speeds, and even single-celled species can experience dramatic evolutionary changes over a relatively short period.”

Russell collaborated with a team that included researchers New Zealand’s Victoria University of Wellington, GNS Science of New Zealand and University of Chicago.

Their paper, “Evolutionary Transition in the Late Neogene Planktonic Foraminiferal Genus Truncorotalia” is available online.