Exploring how the fast-slow pace of life continuum and reproductive strategies structure microorganism life history variation

Abstract

AbstractStudying life history strategies in microorganisms can help predict their performance when complex microbial communities can be categorised into groups of organisms with similar strategies. Microorganisms are typically classified as copiotroph or oligotroph, but it has been proven difficult to generalise their life history strategies to broad lineages. Here we tested if the fast-slow continuum and reproductive strategy framework of macro-organismal life histories can be applied to microorganisms. We used demographic and energy budget data from 13 microorganisms (bacteria, fungi, a protist and plant) to examine how generation time, survivorship, growth form, age at maturity, recruitment success, and net reproductive rate structure microbial life histories. We found that 79% of microorganism life-history variation fell along two uncorrelated axes. Like macroorganisms, we found a fast–slow pace of life continuum, including shorter-lived microorganisms at one end, and longer-lived microorganisms that mature later in life at the other. Also, like macroorganisms, we found a second, reproductive strategy axis, with microorganisms with greater lifetime reproductive success and decreased mortality at older age at one end, and microorganisms with the opposite characteristics at the other end. Microorganismal life history strategies did not covary proportionally to their shared evolutionary history. Thus, whereas this work suggests that the macro-organismal fast-slow continuum and reproductive strategy framework could be realistically applied to microorganisms, their life history processes cannot be inferred from patterns in taxonomic composition.