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

Abstract

Identifying patterns in life history strategies has proven essential to predict how macro-organisms respond to disturbances and stressors. Like macro-organisms, microorganisms display a wide range of growth, cell division and reproduction patterns, but, unlike for macro-organisms, we know little of what determinants structure microorganism life history variation. We used four life history traits that determine growth and reproduction - the von Bertalanffy growth rate, cell length at birth, maximum length, and length at cell division - of 13 microorganisms (bacteria, fungi, a protist and plant) to parameterise a dynamic energy budget integral projection model for each species to calculate its generation time, mean lifetime reproductive success, and population growth rate. Inputting all values into a phylogenetically informed principal component analysis, we show that 91% of microorganism life-history variation falls along two independent axes. Like macro-organisms, we find a fast-slow pace of life continuum, including faster-growing, shorter-lived microorganisms at one end, and slower-growing, longer-lived microorganisms at the other. Unlike macro-organisms, we find a second, size-at-life-stage axis, with microorganisms with shorter birth, division and maximum cell length at one end, and microorganisms with longer lengths at the other. We advocate that this pilot study of structuring microorganism life history variation can ignite future life history research to understand the diversity of microorganismal phenotypes. Such endeavours can aid predictions on how microorganisms respond to disturbances, especially if more complex cell growth and division processes are incorporated.

The sizes of life

“…This assumption is compatible with empirical evidence across marine and terrestrial life with offspring being around two orders of magnitude smaller than adults in mass [ 132 , 133 ]. For microbes, offspring length ( L ) is around 0.2 to 0.5 times of the parent among model organisms [ 134 ]. Since volume (proportional to mass) is approximately 4/3 π L 3 [ 56 ], offspring mass is one to two orders of magnitude smaller than parent mass.…”

DEBBIES to compare life history strategies across ectotherms

“…1) one does require repeated observations on individual growth or survival of individuals within a population. So far, only two small datasets of DEB-IPM parameters have been generated, comprising estimates of the eight life history traits for 13 species of marine megafauna 3 and 13 microorganisms 15 . Here, we introduce a much larger and taxonomically diverse dataset that we refer to as DEBBIES in which we compiled estimates of the eight life history traits for 185 ectotherm species.…”

“…The dataset can be used for a variety of different applications of eco-evolutionary studies (e.g. 15,17 ) (Fig. 1).…”

DEBBIES Dataset to study Life Histories across Ectotherms

“…1) one does require repeated observations on individual growth or survival of individuals within a population. So far, only two small datasets of DEB-IPM parameters have been generated, comprising estimates of the eight life history traits for 13 species of marine megafauna 3 and 13 microorganisms 6 . Here, we introduce a much larger and taxonomically diverse dataset that we refer to as DEBBIES in which we compiled estimates of the eight life history traits for 185 ectotherm species.…”

“…The dataset can be used for a variety of different applications of eco-evolutionary studies (e.g. 6,16 ) (Fig. 1).…”