Abstract
Understanding the factors controlling the relative abundance,
distribution, and diversity of organisms is a fundamental challenge in
ecology. For plants and animals, macroecological rules have been
developed that describe these large-scale distributional patterns and
attempt to explain the underlying physiological and ecological processes
behind them. Similarly, microorganisms exhibit patterns in relative
abundance, distribution, and diversity across space and time, yet it
remains unclear the extent to which microorganisms follow
macroecological rules initially developed for macroorganisms. With rapid
advancements in sequencing technology, we have seen a recent increase in
microbial studies that utilize macroecological frameworks. Here we
review and synthesize these macroecological microbial studies with two
main objectives: (1) to determine to what extent macroecological rules
explain the distribution of host-associated and free-living
microorganisms, and (2) to understand which environmental factors and
stochastic processes may explain these patterns among microbial clades
(archaea, bacteria, fungi, protists) and habitats (host-associated and
free living; terrestrial and aquatic). Our review is the first, to our
knowledge, that examines whether or not the same environmental drivers
contribute to similar trends to macroecological studies when rules are
upheld for microorganisms. Further, we outline several outstanding
questions and recommendations for future studies in microbial ecology.