Cynthia Downs
Cynthia Downs

A paper co-authored by Assistant Professor of Biology Cynthia Downs was recently published by The American Naturalist. “Speeding up growth: selection for mass-independent maximal metabolic rate alters growth rates” describes the results of the authors’ study of the relationship of metabolic rates to pace-of-life.

To determine what measurement of metabolic rate sets the pace-of-life, Downs and her colleagues examined how two measures of metabolic rate at opposite ends of the range of metabolic rates correlated with growth rate.

They compared basal metabolic rate – a measure of the amount of energy required to stay alive –  and maximal metabolic rate – a measurement of the maximal rate at which an individual uses energy aerobically.

Contrary to their expectations, the researchers found little evidence that basal metabolic rate is associated with growth rate. However, selected mice with higher maximal metabolic rates grew faster, indicating that maximal metabolic rate is an important mediator of life histories.

The results suggested that studies investigating associations between energy metabolism and pace-of-life should consider maximal metabolic rate, as it is potentially as important as basal metabolic rate in understanding pace-of-life.

A peer-reviewed publication of the American Society of Naturalists, The American Naturalist is focused on advancing the knowledge of organic evolution and other broad biological principles.

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