14 DAY TRIAL // Higher temperatures near the Equator speed up the metabolisms of the inhabitants, fueling genetic changes that actually lead to the appearance of new species. Researchers now found that the energy necessary to produce a new species is a fixed quantity!
"We've shown that there is indeed a higher rate of evolutionary change in the form and structure of plankton in the tropics and that it increases exponentially because of temperature," said James Gillooly, an assistant professor of zoology with the Genetics Institute at the University of Florida. "It tells us something about the fundamental mechanisms that shape biodiversity on the planet."
Speciation - when animals or plants actually evolve into a new species - occurs when life forms with a common ancestor undergo substantial genetic change. Using a mathematical model based on the body size and temperature-dependence of individual metabolism, the researchers made specific predictions on rates of speciation at the global scale. Then, using fossils and genetic data, they looked at rates of DNA evolution and speciation during a 30-million-year period in foraminifera plankton, a single-celled animal that floats in the ocean.
Researchers compared arrivals of new species of this type of plankton with differences in ocean temperatures at different latitudes ranging from the tropics to the arctic. The results agreed closely with predictions of their model.
The amount of energy required for a new species to appear is the equivalent of the energy released by several million light bulbs in one hour.
"It takes more energy than all the fossil fuel people burn on the planet in a year to form one new species of plankton," said Andrew Allen, the study's lead researcher at the National Center for Ecological Analysis and Synthesis at the University of California, Santa Barbara.
"In terms of conservation, this really highlights that biodiversity does have a price, and the price is very high. From a scientific perspective, we can now quantify biodiversity in terms of energy. This will help efforts to identify and model areas for protection and conservation."
By observing changes in a unicellular animal whose body temperature varies according to its surroundings, as opposed to a mammal, which regulates a constant body temperature, scientists can measure more precisely the rates of speciation caused by the environment. In the end, it is individual metabolic rate - how fast an organism burns food relative to its body weight - that primarily determines evolutionary rate. And higher environmental temperatures help increase metabolism.
One of the novel insights in the paper is the finding that the energy required to produce a new species is a fixed quantity. "These authors are changing evolutionary biology, ecology and biogeography, putting them into a firm and quantitative foundation based on the first principles underlying individual metabolism," said Pablo Marquet, an associate professor and member of the Center for Advanced Studies in Ecology and Biodiversity at the Pontifical Catholic University of Chile, who was not involved in the research.